Dietary glycemic index, glycemic load, insulin index, fiber and whole-grain intake in relation to risk of prostate cancer

Dietary insulin indices and low-carbohydrate diet and the odds of colorectal cancer: a case-control study

BACKGROUND

Regarding the role of insulin and insulin-inducing dietary factors in some cancers' etiology, we hypothesized that the risk of colorectal cancer may be lessened by following a lower carbohydrate and insulinogenic diet. Therefore, we performed this study to explore the association between a low-carbohydrate diet and insulin indices and the odds of colorectal cancer.

METHOD

This hospital-based case-control study was conducted on 150 newly diagnosed colorectal cancer patients and 300 healthy age- and sex-matched hospitalized controls. A valid and reliable food frequency questionnaire was used to calculate the insulin indices and low-carbohydrate diet score. Multivariate logistic regression was used to estimate the association between insulin indices and low-carbohydrate diet and the odds of colorectal cancer.

RESULT

After adjusting for potential confounders, individuals in the highest tertile of insulin indices had a higher risk of colorectal cancer (OR insulin index  = 3.46; 95% CI, 2.00-5.96; OR insulin load  = 2; 95% CI, 1.17-3.41). No association was found between a low-carbohydrate diet and colorectal cancer (OR = 1.55; 95% CI, 0.85-2.84).

CONCLUSION

Current results demonstrated that a high insulinemic diet was associated with a higher risk of colorectal cancer.

Dietary Fiber Intake and Risk of Advanced and Aggressive Forms of Prostate Cancer: A Pooled Analysis of 15 Prospective Cohort Studies

BACKGROUND

Evidence of an association between dietary fiber intake and risk of advanced and aggressive forms of prostate cancer (PC) and PC mortality is limited.

OBJECTIVE

The aim of this study was to examine associations between intakes of dietary fiber overall and by food source and risk of advanced and aggressive forms of PC.

DESIGN

The study design was a pooled analysis of the primary data from 15 cohorts in 3 continents. Baseline dietary fiber intake was assessed using a validated food frequency questionnaire or diet history in each study.

PARTICIPANTS/SETTING

There were 842 149 men followed for up to 9 to 22 years between 1985 and 2009 across studies.

MAIN OUTCOME MEASURES

The primary outcome measures were advanced (stage T4, N1, or M1 or PC mortality), advanced restricted (excluded men with missing stage and those with localized PC who died of PC), and high-grade PC (Gleason score ≥8 or poorly differentiated/undifferentiated) and PC mortality.

STATISTICAL ANALYSIS PERFORMED

Study-specific multivariable hazard ratios (MVHR) were calculated using Cox proportional hazards regression and pooled using random effects models.

RESULTS

Intake of dietary fiber overall, from fruits, and from vegetables was not associated with risk of advanced (n = 4863), advanced restricted (n = 2978), or high-grade PC (n = 9673) or PC mortality (n = 3097). Dietary fiber intake from grains was inversely associated with advanced PC (comparing the highest vs lowest quintile, MVHR 0.84; 95% CI 0.76-0.93), advanced restricted PC (MVHR 0.85; 95% CI 0.74-0.97), and PC mortality (MVHR 0.78; 95% CI 0.68-0.89); statistically significant trends were noted for each of these associations (P ≤ .03), and a null association was observed for high-grade PC for the same comparison (MVHR 1.00; 95% CI 0.93-1.07). The comparable results were 1.06 (95% CI 1.01-1.10; P value, test for trend = .002) for localized PC (n = 35,199) and 1.05 (95% CI 0.99-1.11; P value, test for trend = .04) for low/intermediate grade PC (n = 34 366).

CONCLUSIONS

Weak nonsignificant associations were observed between total dietary fiber intake and risk of advanced forms of PC, high-grade PC, and PC mortality. High dietary fiber intake from grains was associated with a modestly lower risk of advanced forms of PC and PC mortality.

Association of glycaemic index and glycaemic load with type 2 diabetes, cardiovascular disease, cancer, and all-cause mortality: a meta-analysis of mega cohorts of more than 100 000 participants

BACKGROUND

There is debate over whether the glycaemic index of foods relates to chronic disease. We aimed to assess the associations between glycaemic index (GI) and glycaemic load (GL) and type 2 diabetes, cardiovascular disease, diabetes-related cancers, and all-cause mortality.

METHODS

We did a meta-analysis of large cohorts (≥100 000 participants) identified from the Richard Doll Consortium. We searched the Cochrane Library, MEDLINE, PubMed, Embase, Web of Science, and Scopus for cohorts that prospectively examined associations between GI or GL and chronic disease outcomes published from database inception to Aug 4, 2023. Full-article review and extraction of summary estimates data were conducted by three independent reviewers. Primary outcomes were incident type 2 diabetes, total cardiovascular disease (including mortality), diabetes-related cancers (ie, bladder, breast, colorectal, endometrial, hepatic, pancreatic, and non-Hodgkin lymphoma), and all-cause mortality. We assessed comparisons between the lowest and highest quantiles of GI and GL, adjusting for dietary factors, and pooling their most adjusted relative risk (RR) estimates using a fixed-effects model. We also assessed associations between diets high in fibre and whole grains and the four main outcomes. The study protocol is registered with PROSPERO, CRD42023394689.

FINDINGS

From ten prospective large cohorts (six from the USA, one from Europe, two from Asia, and one international), we identified a total of 48 studies reporting associations between GI or GL and the outcomes of interest: 34 (71%) on various cancers, nine (19%) on cardiovascular disease, five (10%) on type 2 diabetes, and three (6%) on all-cause mortality. Consumption of high GI foods was associated with an increased incidence of type 2 diabetes (RR 1·27 [95% CI 1·21-1·34]; p<0·0001), total cardiovascular disease (1·15 [1·11-1·19]; p<0·0001), diabetes-related cancer (1·05 [1·02-1·08]; p=0·0010), and all-cause mortality (1·08 [1·05-1·12]; p<0·0001). Similar associations were seen between high GL and diabetes (RR 1·15 [95% CI 1·09-1·21]; p<0·0001) and total cardiovascular disease (1·15 [1·10-1·20]; p<0·0001). Associations between diets high in fibre and whole grains and the four main outcomes were similar to those for low GI diets.

INTERPRETATION

Dietary recommendations to reduce GI and GL could have effects on health outcomes that are similar to outcomes of recommendations to increase intake of fibre and whole grain.

FUNDING

Banting and Best and the Karuna Foundation.

Higher insoluble fiber intake is associated with a lower risk of prostate cancer: results from the PLCO cohort

Studies regarding the relationship between fiber intake and prostate cancer (PCa) have conflicting results. Therefore, this study examined the relationship between fiber intake and the risk of PCa by using data from Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial. A total of 54,336 participants in the United States, consisting of 6,414 patients with PCa, were included in this study. Multivariate Cox regression models were applied to estimate adjusted hazard ratios (aHRs) and corresponding 95% confidence intervals (CIs). Compared with individuals in the lowest quartile, individuals in the highest quartile of insoluble fiber intake had a significantly lower risk of PCa (aHR, 0.87; 95% CI, 0.78-0.98). By contrast, no significant associations were detected between total fiber intake (aHR, 0.90; 95% CI, 0.80-1.01) or soluble fiber intake (aHR, 0.90; 95% CI, 0.80-1.02). Subgroup analyses showed that insoluble fiber was related to a decreased risk of PCa in subjects with the following characteristics: age > 65 years, nonsmoking or former smokers, education level ≤ high school, non-Hispanic white ethnicity, or without a family history of PCa. In addition, significant combined effects of insoluble fiber intake, age and family history of PCa on the risk of PCa were observed, but no combined effects of smoking status and insoluble fiber intake were observed. In addition, total fiber, insoluble fiber, and soluble fiber intake had no influence on the mortality of PCa patients. These results show that all 3 measures of fiber suggest a protective association, but insoluble fiber may have a stronger association with the risk of PCa. Future studies are warranted to further investigate these relationships.

Dietary Approach of Patients with Hormone-Related Cancer Based on the Glycemic Index and Glycemic Load Estimates

Hormone-related cancers, namely breast, endometrial, cervical, prostate, testicular, and thyroid, constitute a specific group of cancers dependent on hormone levels that play an essential role in cancer growth. In addition to the traditional risk factors, diet seems to be an important environmental factor that partially explains the steadily increased prevalence of this group of cancer. The composition of food, the dietary patterns, the endocrine-disrupting chemicals, and the way of food processing and preparation related to dietary advanced glycation end-product formation are all related to cancer. However, it remains unclear which specific dietary components mediate this relationship. Carbohydrates seem to be a risk factor for cancer in general and hormone-related cancers, in particular, with a difference between simple and complex carbohydrates. Glycemic index and glycemic load estimates reflect the effect of dietary carbohydrates on postprandial glucose concentrations. Several studies have investigated the relationship between the dietary glycemic index and glycemic load estimates with the natural course of cancer and, more specifically, hormone-related cancers. High glycemic index and glycemic load diets are associated with cancer development and worse prognosis, partially explained by the adverse effects on insulin metabolism, causing hyperinsulinemia and insulin resistance, and also by inflammation and oxidative stress induction. Herein, we review the existing data on the effect of diets focusing on the glycemic index and glycemic load estimates on hormone-related cancers.

Adolescent dietary patterns in relation to later prostate cancer risk and mortality in the NIH-AARP Diet and Health Study

BACKGROUND

Although adolescent diet has been proposed to contribute to prostate cancer (PCa) development, no studies have investigated the relation between adolescent dietary patterns and PCa risk or mortality.

METHODS

Using data from 164,079 men in the NIH-AARP Diet and Health Study, we performed factor analysis to identify dietary patterns at ages 12-13 years and then used Cox proportional hazards regression to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) of total (n = 17,861), non-advanced (n = 15,499), advanced (n = 2362), and fatal PCa (n = 832).

RESULTS

Although not entirely consistent across analyses, a higher adolescent plant-based pattern (characterised by vegetables, fruits, and dark bread) score was associated with slightly reduced risks of total (fully adjusted HRQ5vs.Q1 = 0.93, 95% CI: 0.89-0.98, p trend=0.003) and non-advanced PCa (HR = 0.91, 95% CI: 0.87-0.96, p trend<0.001), whereas no associations were observed for advanced or fatal PCa, or for Western modern (characterised by sweets, processed meat, beef, cheese, and pizza) or Western traditional (characterised gravy, eggs, potatoes and white bread) patterns.

CONCLUSION

We found evidence to support a modest, protective role for a plant-based dietary pattern during adolescence on PCa risk. If confirmed in future studies, our findings may help to inform the development of new, primary prevention strategies for PCa.

The association of dietary insulin load and index with the risk of cancer and cancer mortality: a systematic review and meta-analysis

Purpose

Insulin levels play an important role in cancer development. However, the link between an insulinogenic diet and cancer is still unclear. Therefore, we performed a systematic review with meta-analysis to investigate the association between dietary insulin index (II) and load (IL) with cancer risk and mortality.

Methods

A comprehensive search between electronic databases (Web of Science, PubMed/Medline, Scopus, and Google Scholar) was conducted to identify relevant studies up to January 2022. The relative risks (RR) and Odds ratios (OR) were extracted from eligible studies, and meta-analysis was performed to calculate the pooled effect size.

Result

12 papers including 14 studies (10 cohorts and 4 case-control) were included for the meta-analysis. Among them, 10 studies reported effect size for the risk of cancer, and 4 studies reported effect size for cancer mortality. We observed no significant association between II and IL with cancer overall (RR_II: 1.03, 95%CI: 0.91-1.17, RR_IL: 1.16, 95%CI: 0.94-1.42) and in cohort studies, however, in case-control studies was related with higher odds of cancer (OR_II: 2.30, 95%CI: 1.21-4.38, OR_IL: 2.57, 95%CI: 1.64-4.02). Higher II and IL scores were associated with the increased risk of total (RR_II: 1.29, 95%CI: 1.02-1.63) and (RR_IL: 1.39, 95%CI: 1.06-1.83) and colorectal cancer mortality (RR_II: 1.29, 95%CI: 1.13-1.48) and (RR_IL: 1.37, 95%CI: 1.18-1.60).

Conclusion

Higher dietary II and IL were not associated with cancer risk in overall and cohort studies, whereas related with a higher risk of cancer in case-control studies. We observed a significant positive relation of II and IL with cancer mortality, especially CRC mortality.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-022-01013-3.

Dietary insulin index and load with risk of breast cancer in a case-control study

OBJECTIVE

Circulating insulin levels have been positively associated with risk of breast cancer (BrCa); however, it remains unclear whether a diet inducing an elevated insulin response influences Breast risk.

METHODS

In this study, 250 newly diagnosed breast cancer patients and 250 hospitalised controls were recruited using convenience sampling. The dietary insulin index (DII) was calculated by dividing the dietary insulin load by the total energy intake.

RESULTS

Compared with those in the lowest tertiles of DII and dietary insulin load (DIL), subjects in the highest tertile were more likely to be overweight, have a family history of breast and other types of cancer and a history of benign breast diseases. After controlling for multiple potential confounders, a significantly increased BrCa odds was observed in the highest tertiles of DII and DIL score compared with the lowest tertiles (odds ratio (OR): 1.46; 95% CI: 0.67-3.19, P = .006) and (OR: 1.87; 95% CI: 0.92-3.80, P = .038), respectively.

CONCLUSIONS

Our findings suggest that a diet that induces an elevated postprandial insulin response, indicated by higher DII and DIL scores, may increase the odds of BrCa, especially among women.

Adolescent Plant Product Intake in Relation to Later Prostate Cancer Risk and Mortality in the NIH-AARP Diet and Health Study

BACKGROUND

Although fruit and vegetable intake during adolescence, a potentially sensitive time period for prostate cancer (PCa) development, has been proposed to protect against PCa risk, few studies have investigated the role of adolescent plant product intake in PCa development.

METHODS

Intake of various vegetables, fruit, and grains by males at ages 12-13 y was examined in relation to later PCa risk and mortality in the NIH-AARP Diet and Health Study. Cox proportional hazards regression was used to calculate HRs and 95% CIs of nonadvanced (n = 14,238) and advanced (n = 2,170) PCa incidence and PCa mortality (n = 760) during 1,729,896 person-years of follow-up.

RESULTS

None of the plant products examined were associated consistently with all PCa outcomes. However, greater adolescent intakes of tomatoes (P-trend = 0.004) and nonstarch vegetables (P-trend = 0.025) were associated with reduced risk of nonadvanced PCa, and greater intakes of broccoli (P-trend = 0.050) and fruit juice (P-trend = 0.019-0.025) were associated with reduced risk of advanced PCa and/or PCa mortality. Positive trends were also observed for greater intakes of fruit juice (P-trend = 0.002), total fruit (P-trend = 0.014), and dark bread (P-trend = 0.035) with nonadvanced PCa risk and for greater intakes of legumes (P-trend < 0.001), fiber (P-trend = 0.001), and vegetable protein (P-trend = 0.013-0.040) with advanced PCa risk or PCa mortality.

CONCLUSIONS

Our findings do not provide strong evidence to suggest that adolescent plant product intake is associated with reduced PCa risk.

Evaluation of glycemic index, antioxidant capacity, and metabolic effects of a fermented beverage made from Changbai Mountain fruit and vegetables

Fermented foods and beverages have been known to be beneficial when included in the human diet. This study examined the glycemic index (GI) of a fermented beverage (FB) made from Changbai Mountain fruit and vegetables in humans and its antioxidant capacity and metabolic effects in a rat model of diabetes. Twenty healthy volunteers were tested with 50 g of glucose and 50 g equivalent of carbohydrates from FB on two separate days for GI measurement. The rats were randomly divided into blank control group (n = 15) and diabetic model (DM) group (n = 75). DM group were randomly divided into five groups, positive control group, model control group and three FB treatment (2.5, 5, 10 ml/kg·bw·d) groups. The general indices, including blood glucose and lipid levels and antioxidant index, of the rats were measured to investigate the effect of FB. The GI of FB was found to be 56.99, indicating it as a medium GI food. Compared to model control group, the low-dose FB group had lower blood glucose levels and higher high-density lipoprotein cholesterol levels in DM rats (p < .05). Medium- and high-dose FB decreased the serum malonaldehyde levels in DM rats compared to those in the model control group. The FB-treated DM rat groups showed increased serum glutathione and superoxide dismutase levels compared with those in the model control group (p < .05). FB is a medium GI food that plays a protective role against oxidative stress in DM rats. PRACTICAL APPLICATIONS: The present study evaluated the glycemic index of a fermented beverage (FB) made from Changbai Mountain fruit and vegetables in humans and investigated its antioxidant capacity and metabolic effects in a rat diabetes model. The study results may aid in the development of FB from fruits and vegetables and provide a theoretical basis for further research and development.

Dietary Carbohydrate Intake Glycemic Index and Glycemic Load and the Risk of Prostate Cancer among Iranian Men: A Case-Control Study

Previous studies have presented a few evidences on the relationship between dietary carbohydrate intake, glycemic index (GI), glycemic load (GL), with the prostate cancer risk. We performed a case-control study to evaluate these associations in 50 men with histologically confirmed prostate cancer and 100 control men. Odds ratios (ORs) and their corresponding 95% confidence intervals (95% CIs) were derived using logistic regression. The fully adjusted ORs for the top vs. the bottom quartile were 15.02 (P trend = 0.004), 1.04 (P trend = 0.003), and 10.35 (P trend = 0.002) for carbohydrate intake, GI and GL, respectively. Significant associations with prostate cancer remained only among men with reduced fiber intake for carbohydrate intake, GI and GL and among those had increased fiber intake for GI. These findings support the hypothesis that diet with high carbohydrate, GI and GL enhance risk of prostate cancer.

Dietary Insulin Index and Insulin Load in Relation to Breast Cancer: Findings from a Case-Control Study

BACKGROUND

No data are available on the association between dietary insulin index (DII) and dietary insulin load (DIL) and the risk of breast cancer (BC).

PATIENTS AND METHODS

This hospital-based case-control study enrolled 150 newly diagnosed cases of BC and 150 age-matched controls. All cases were patients with pathologically confirmed BC, with no history of any type of other pathologically confirmed cancers. Controls were selected from visitors, relatives, and friends of non-cancer patients in other wards who had no family relationships with the cases. We assessed the dietary intakes of study participants using a validated 147-item semiquantitative food frequency questionnaire. DII and DIL were obtained from previously published data.

RESULTS

A significant positive association was found between DII and BC (odds ratio [OR], 1.82; 95% confidence interval [CI], 1.02-3.25), such that after considering energy intake and age, participants in the highest tertile of DII had 1.86 times greater risk of BC than those in the lowest tertile (OR, 1.86; 95% CI, 1.03-3.35). However, this association became non-significant after controlling for further potential risk factors (OR, 3.26; 95% CI, 0.9-11.7). Furthermore, we observed a significant positive association between DIL and BC (OR, 1.9; 95% CI, 1.06-3.40). The association remained significant even after controlling for age and energy intake. Further controlling for other potential confounders resulted in the disappearance of the association (OR, 3.06; 95% CI, 0.87-10.6).

CONCLUSION

Adherence to a diet with high DII and DIL was not associated with odds of BC after controlling for potential confounders.

Dietary glycemic index, glycemic load, insulin index, insulin load and risk of diabetes-related cancers: A systematic review of cohort studies

BACKGROUND & AIMS

It is believed that diets high in glycemic index (GI), glycemic load (GL), Insulin index (II), and Insulin load (IL) are associated with the increased risks of certain cancers through increasing serum glucose or insulin levels.

METHODS

We conducted this systematic review of cohort studies to evaluate the possible relation between GI, GL, II, and IL with diabetes-related cancers, including colorectal, bladder, breast, endometrium, liver, pancreas, and prostate cancers. Two separate investigators conducted a literature search through PubMed/Medline, Scopus, and Web of Science databases up to February 2020, plus reference lists of relevant articles.

RESULTS

Fifty-three cohort studies with a total of 100 098 cancer cases were included in this systematic review. Fifteen out of eighteen studies among breast cancer cases reported no significant association between GI/GL and cancer risk. These numbers were 4 out of 13 for colorectal cancer, 7 out of 9 for endometrial cancer, 2 out of 3 for liver cancer, 8 out of 10 for pancreatic cancer, and 3 out of 3 for prostate cancer. Only one cohort investigated this association in terms of bladder cancer and reported a significant association. Also, five studies reported this relation in terms of II/IL, and only one cohort among endometrial cancer patients observed a significant positive association between the risk of cancer and IL.

CONCLUSION

We concluded a weak association between dietary GI/GL and no association between II/IL with diabetes-related cancer risk. More cohort studies are required to be performed regarding II/IL and the risk of cancer.

Whole Grains, Refined Grains, and Cancer Risk: A Systematic Review of Meta-Analyses of Observational Studies

PubMed, Web of Science, and the Cochrane Database of Systematic Reviews were searched for meta-analyses that provided risk estimates (±95% confidence intervals) for associations between intakes of whole and refined grains and risk of total and site-specific cancer. The preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines were followed. Only meta-analyses that included whole grains and refined grains as separate food groups, and not as part of dietary patterns, were included. A total of 17 publications were identified that met inclusion criteria. Within these, results from a total of 54 distinct meta-analyses were reported for whole grains and 5 meta-analyses for refined grains. For total cancer mortality, 7 meta-analyses of cohort studies indicated that whole grain intake was associated with 6% to 12% lower risk in comparison of highest vs. lowest intake groups, and 3% to 20% lower risk for doses ranging from 15 to 90 g/day. For site-specific cancers, meta-analyses indicated that whole grain intake was consistently associated with lower risks of colorectal, colon, gastric, pancreatic, and esophageal cancers. Limited data were available for refined grains, with only 4 publications providing risk estimates, and only 1 of the meta-analyses included more than 3 studies. High intake of refined grains was associated with increased risk of colon and gastric cancer. By contrast, in the only dose-response meta-analysis, each 90 g/day consumption of refined grains was associated with a 6% lower risk of total cancer. In addition to the limited number of published meta-analyses on refined grains, results were also weakened due to the fact that refined grains were frequently defined to include both staple grain foods and indulgent grain foods, and the majority of studies included in the meta-analyses provided no specific definition of refined grains. Overall, meta-analyses of cohort and case-control studies consistently demonstrate that whole grain intake is associated with lower risk of total and site-specific cancer, and support current dietary recommendations to increase whole grain consumption. By contrast, the relationship between refined grain intake and cancer risk is inconclusive.

A nutrient-wide association study for risk of prostate cancer in the European Prospective Investigation into Cancer and Nutrition and the Netherlands Cohort Study

PURPOSE

The evidence from the literature regarding the association of dietary factors and risk of prostate cancer is inconclusive.

METHODS

A nutrient-wide association study was conducted to systematically and comprehensively evaluate the associations between 92 foods or nutrients and risk of prostate cancer in the European Prospective Investigation into Cancer and Nutrition (EPIC). Cox proportional hazard regression models adjusted for total energy intake, smoking status, body mass index, physical activity, diabetes and education were used to estimate hazard ratios and 95% confidence intervals for standardized dietary intakes. As in genome-wide association studies, correction for multiple comparisons was applied using the false discovery rate (FDR < 5%) method and suggested results were replicated in an independent cohort, the Netherlands Cohort Study (NLCS).

RESULTS

A total of 5916 and 3842 incident cases of prostate cancer were diagnosed during a mean follow-up of 14 and 20 years in EPIC and NLCS, respectively. None of the dietary factors was associated with the risk of total prostate cancer in EPIC (minimum FDR-corrected P, 0.37). Null associations were also observed by disease stage, grade and fatality, except for positive associations observed for intake of dry cakes/biscuits with low-grade and butter with aggressive prostate cancer, respectively, out of which the intake of dry cakes/biscuits was replicated in the NLCS.

CONCLUSIONS

Our findings provide little support for an association for the majority of the 92 examined dietary factors and risk of prostate cancer. The association of dry cakes/biscuits with low-grade prostate cancer warrants further replication given the scarcity in the literature.

Insulin Reduces the Efficacy of Vemurafenib and Trametinib in Melanoma Cells

Background

Despite the progress made in the clinical management of metastatic melanoma, a patient’s response to treatment cannot be fully predicted, and intrinsic or acquired resistance that is developed in most melanoma patients warrants further research efforts. In addition to genetic factors, microenvironmental input should be considered to explain the diversity of response to treatment among melanoma patients. In this study, we evaluated the impact of insulin on patient-derived BRAF^V600E melanoma cells, either untreated or treated with vemurafenib or trametinib, inhibitors of BRAF^V600 and MEK1/2, respectively.

Methods

Cells were cultured in serum-free conditions, either with or without insulin. The activity of the MAPK/ERK and PI3K/AKT pathways was assessed by Western blotting, cell viability, and percentages of Ki-67- and NGFR-positive cells by flow cytometry. Transcript levels were analyzed using qRT-PCR, and γ-H2AX levels by immunoblotting and confocal microscopy. A luminescence-based assay was used to measure glutathione content.

Results

While insulin did not influence the MAPK/ERK pathway activity, it had a strong influence on melanoma cells, in which this pathway was suppressed by either vemurafenib or trametinib. In the presence of insulin, both drugs were much less efficient in 1) inhibiting proliferation and reducing the percentage of Ki-67-positive cells, and 2) inducing apoptosis and phosphorylation of histone H2AX in melanoma cells. Changes induced by vemurafenib and trametinib in glutathione homeostasis and DNA repair gene expression were also attenuated by insulin. Moreover, insulin impaired the combined effects of targeted drugs and doxorubicin in melanoma cells. In addition to insulin-induced PI3K/AKT activity, which was either transient or sustainable depending on the cell line, an insulin-triggered increase in the percentage of cells expressing NGFR, a marker of neural crest stem-like cells, may contribute to the reduced drug efficacy.

Conclusion

Our results demonstrate the role of insulin in reducing the efficacy of vemurafenib and trametinib. This needs clinical assessment.

Whole grain consumption and human health: an umbrella review of observational studies

Whole grains have been associated with a number of health benefits. We systematically reviewed existing meta-analyses of observational studies and evaluated the level of evidence for their putative effects based on pre-selected criteria. Of the 23 included studies, we found convincing evidence of an inverse association between whole grain consumption and risk of type-2 diabetes and colorectal cancer; possible evidence of decreased risk of colon cancer and cardiovascular mortality with increased whole grain intake, as well as increased risk of prostate cancer. Limited or insufficient evidence was available for all other outcomes investigated. Overall findings are encouraging for a positive effect of whole grain consumption on certain diseases, especially highly prevalent metabolic diseases, however, uncertainty of some negative associations deserves further attention.

Dietary insulin index and insulin load in relation to glioma: findings from a case-control study

BACKGROUND

Although hyperinsulinemia is assumed to be involved in brain carcinogenesis, data on the link between dietary insulin index (DII) and dietary insulin load (DIL) and risk of glioma are lacking.

OBJECTIVE

The current study aimed to investigate the relation between DII and DIL and risk of glioma in a case-control study among Iranian adults.

METHODS

In this hospital-based case-control study, 128 pathologically confirmed cases of glioma and 256 age and sex-matched controls were enrolled. Dietary intakes of study participants were assessed using a validated Block-format 123-item semi-quantitative FFQ. DII and DIL were computed using a published food insulin index (FII) data.

RESULTS

A significant positive association was found between DIL and glioma (OR: 3.56; 95% CI: 1.85-6.58, P < 0.001); such that after controlling for potential confounders, participants in the highest quartile of DIL had 2.95 times greater odds of glioma than those in the lowest quartile (OR: 2.95; 95% CI: 1.40-6.24, P_trend=0.006). Furthermore, we observed a significant positive association between DII and glioma (OR: 2.65; 95% CI: 1.43-4.93, P_trend= 0.001). This association remained significant even after considering energy intake (OR: 2.66; 95% CI: 1.43-4.95, P_trend = 0.001). However, when further potential confounders were taken into account, this relationship became non-significant (OR: 1.87; 95% CI: 0.92-3.80, P_trend = 0.03), despite a significant trend of increased odds ratios (P = 0.03).

CONCLUSIONS

In conclusion, we found a significant positive association between DIL and odds of glioma. DII was not significantly associated with odds of glioma after controlling for confounders.

Dietary Glycemic Index and Glycemic Load and the Risk of Prostate Cancer: An Updated Systematic Review and Dose-Response Meta-Analysis

A meta-analysis in 2015 revealed no significant association between glycemic index (GI), glycemic load (GL), and prostate cancer. Moreover, until now, no study has examined the dose-response association of GI, GL, and prostate cancer yet. The online databases were searched by two independent researchers for relevant publications up to Jan. 2019, using relevant keywords. Nine studies including five prospective and four case-control studies were included in the current systematic review and meta-analysis. These studies have included 290,911 individuals. We found a significant positive dose-response association between dietary GI and prostate cancer (P_nonlinearity = 0.03). Comparing individuals in the highest category of GI with those in the lowest category, no significant association was found between GI and prostate cancer (combined effect size: 1.08, 95% CI: 0.97-1.19, P = 0.17). Furthermore, no significant association was seen between dietary GL and prostate cancer in both dose-response analysis and when comparing the highest versus lowest categories of GL (combined effect size: 1.03, 95% CI: 0.91-1.16, P = 0.65). In conclusion, we found a significant positive dose-response association between dietary GI and prostate cancer. However, significant association was not seen for dietary GL.

Dietary Fat and Sugar in Promoting Cancer Development and Progression

The uncontrolled cellular growth that characterizes tumor formation requires a constant delivery of nutrients. Since the 1970s, researchers have wondered if the supply of nutrients from the diet could impact tumor development. Numerous studies have assessed the impact of dietary components, specifically sugar and fat, to increased cancer risk. For the most part, data from these trials have been inconclusive; however, this does not indicate that dietary factors do not contribute to cancer progression. Rather, the dietary contribution may be dependent on tumor, patient, and context, making it difficult to detect in the setting of large trials. In this review, we combine data from prospective cohort trials with mechanistic studies in mice to argue that fat and sugar can play a role in tumorigenesis and disease progression. We find that certain tumors may respond directly to dietary sugar (colorectal and endometrial cancers) and fat (prostate cancer) or indirectly to the obese state (breast cancer).

Optimization of enzymes addition to improve whole wheat bread making quality by response surface methodology and optimization technique

The functional ingredients in whole wheat flour, such as dietary fiber, vitamins, and minerals, have beneficial health effects. However, the excessive amount of dietary fiber in whole wheat flour inhibits gluten network formation and diminishes bread making qualities (BMQ). Adding appropriate amounts of enzymes, α-amylase (AM) and hemicellulase (HC), could be a solution to these problems. In this study, response surface methodology (RSM) created a response surface model and Solver (Excel add-in software) calculated the optimal amounts of the enzymes. Adding optimum concentrations of AM and HC drastically improved BMQ (gas retention of dough, specific loaf volume, and bread staling) of whole wheat flour dough and bread compared to whole wheat flour dough and bread without the enzymes. These results showed that combining RSM and Solver was an effective and reasonably easy method that determines optimal concentrations of enzymes to obtain the highest quality bread using whole wheat flour.

Pre-diagnostic carbohydrate intake and treatment failure after radical prostatectomy for early-stage prostate cancer

PURPOSE

An association between dietary carbohydrate intake and prostate cancer (PCa) prognosis is biologically plausible, but data are scarce. This prospective cohort study examined the relation between pre-diagnostic carbohydrate intake and treatment failure following radical prostatectomy for clinically early-stage PCa.

METHODS

We identified 205 men awaiting radical prostatectomy and assessed their usual dietary intake of carbohydrates using the 110-item Block food frequency questionnaire. We also evaluated carbohydrate intake quality using a score based on the consumption of sugars relative to fiber, fat, and protein. Logistic regression analyzed their associations with the odds of treatment failure, defined as a detectable and rising serum prostate-specific antigen (PSA) or receiving androgen deprivation therapy (ADT) within 2 years.

RESULTS

Sucrose consumption was associated with a higher odds and fiber consumption with a lower odds of ADT after accounting for age, race/ethnicity, body mass index, and tumor characteristics (odds ratio [OR] (95% confidence interval [CI]) 5.68 (1.71, 18.9) for 3rd vs. 1st sucrose tertile and 0.88 (0.81, 0.96) per gram of fiber/day, respectively). Increasing carbohydrate intake quality also associated with a lower odds of ADT (OR (95% CI) 0.78 (0.66, 0.92) per unit increase in score, range 0-12).

CONCLUSIONS

Pre-diagnostic dietary carbohydrate intake composition and quality influence the risk of primary treatment failure for early-stage PCa. Future studies incorporating molecular aspects of carbohydrate metabolism could clarify possible underlying mechanisms.

Associations between dietary inflammatory index and incidence of breast and prostate cancer: a systematic review and meta-analysis

OBJECTIVES

Dietary inflammatory index (DII) scores have been inconsistently linked to cancer risks. Therefore, a systematic review and meta-analysis was performed to examine the associations between the DII and the risks of breast and prostate cancer among men and women.

METHODS

Relevant studies were identified by searching PubMed and EMBASE databases up to March 2018. Data were available from 13 studies; of these, four studies used a prospective cohort design and nine studies were case-control studies. A total of 231 947 individuals from nine countries were included in these studies for the meta-analysis. The results were pooled using a random-effects model.

RESULTS

A pooled, adjusted odds ratio (OR) analysis indicated that there was a direct relationship between the highest versus lowest DII scores and prostate cancer risk in men (OR: 1.31; 95% CI: 1.04-1.57) but not the breast cancer risk (BCR) in women (OR: 1.65; 95% CI: 0.96-2.33). In the subgroup analyses, a more significant association between DII score and increased BCR was noted in premenopausal (OR: 2.03; 95% CI: 1.06-3.00) than in postmenopausal women (OR: 1.52; 95% CI: 0.89-2.16). When the results were stratified by body mass index, a positive association was observed between DII score and increased BCR in women (OR: 1.83; 95% CI: 1.48-2.18). Furthermore, there was no significant association between the highest versus lowest DII score and BCR among women who received hormone therapy (OR: 1.29; 95% CI: 0.93-1.64).

CONCLUSIONS

Men and premenopausal women who exhibit higher DII scores have increased prostate and breast cancer incidence risks, respectively. Moreover, body mass index had positive associations with the relationship between DII score and BCR in women. Further prospective cohort studies with longer follow-up periods are needed to support this possible association between DII score and cancer incidence.

Association of whole grain intake with all-cause, cardiovascular, and cancer mortality: a systematic review and dose-response meta-analysis from prospective cohort studies

BACKGROUND/OBJECTIVES

Whole grains are rich source of nutrients and have shown beneficial effects on human health. This study was designed to systematically review the existing results and quantitatively assess the dose-response relationship of whole grain intake with all-cause and cause-specific mortality.

SUBJECTS/METHODS

We searched 'whole grain' or 'whole grains' in combination with 'mortality'' or 'cardiovascular disease' or 'cancer' through the Web of Science and PubMed databases till 20 January 2016. To be eligible for inclusion, publications should be prospective cohort studies and reported the influence of whole grain intake on human mortality. Relative risks (RRs) and 95% confidence intervals (CIs) from the included studies were pooled by a random effects model or fixed effect model.

RESULTS

We included 19 cohort studies from 17 articles, with 1 041 692 participants and 96 710 deaths in total, in the analyses. We observed an inverse relationship of whole grain intake with risk of total, cardiovascular disease and cancer mortality. The pooled RR was 0.84 (95% CI 0.81-0.88, n=9) for total mortality, 0.83 (95% CI 0.79-0.86, n=8) for CVD mortality and 0.94 (95% CI 0.87-1.01, n=14) for cancer mortality, comparing the highest intake of whole grain with the lowest category. For dose-response analysis, we found a nonlinear relationship of whole grain intake with risk of total, cardiovascular and cancer mortality. Each 28 g/d intake of whole grains was associated with a 9% (pooled RR: 0.91 (0.90-0.93)) lower risk for total mortality, 14% (pooled RR: 0.86 (0.83-0.89)) lower risk for CVD mortality and 3% (pooled RR: 0.97 (0.95-0.99)) lower risk for cancer mortality.

CONCLUSIONS

Our study shows that whole grain intake was inversely associated with risk of total, CVD and cancer mortality. Our results support current dietary guidelines to increase the intake of whole grains. Government officials, scientists and medical staff should take actions to promote whole grains intake.

The β-cell burden index of food: A proposal

The quantity and quality of dietary fat and/or carbohydrate may alter one or more of the basic components of the insulin-glucose system, which in turn affect the pathways leading to alterations in glucose homeostasis and, possibly, to cardiovascular disease. This viewpoint article, reviewing some of the currently available tools aiming at quantifying the impact of dietary carbohydrates on the glucose-insulin homeostatic loop, highlights the unmet need of a more thorough assessment of the complex interaction between dietary factors and the glucose-insulin system. A novel index, the "β-cell burden index", may turn out to be a valuable tool to quantify the role played by the diet in shaping the risk of type 2 diabetes, cardiovascular disease and other metabolic and degenerative disorders, ideally orienting their prevention with strategies based on dietary modifications.

Total antioxidant intake and prostate cancer in the Cancer of the Prostate in Sweden (CAPS) study. A case control study

Background

The total intake of dietary antioxidants may reduce prostate cancer risk but available data are sparse and the possible role of supplements unclear. We investigated the potential association between total and dietary antioxidant intake and prostate cancer in a Swedish population.

Methods

We used FFQ data from 1499 cases and 1112 controls in the population based case–control study Cancer of the Prostate in Sweden (CAPS). The ferric reducing antioxidant potential (FRAP) assay was used to assess the total antioxidant capacity (TAC) of diet and supplements. We calculated odds ratios (ORs) for the risk of prostate cancer across quintiles of antioxidant intake from all foods, from fruit and vegetables only, and from dietary supplements using unconditional logistic regression.

Results

Coffee comprised 62 % of the dietary antioxidant intake, tea 4 %, berries 4 %, chocolate 2 %, and boiled potatoes 2 %. In total 19 % and 13 % of the population took multivitamins and supplemental Vitamin C respectively, on a regular basis. Antioxidant intake from all foods and from fruits and vegetables separately measured by the FRAP assay was not associated with prostate cancer risk. For antioxidant intake from supplements we found a positive association with total, advanced, localized, high grade and low grade prostate cancer in those above median supplemental TAC intake of users compared to non-users (Adjusted ORs for total prostate cancer: 1.37, 95 % CI 1.08–1.73, advanced: 1.51, 95 % CI 1.11–2.06, localized: 1.36. 95 % CI 1.06–1.76, high grade 1.60, 95 % CI 1.06–2.40, low grade 1.36, 95 % CI 1.03–1.81). A high intake of coffee (≥6 cups/day) was associated with a possible risk reduction of fatal and significantly with reduced risk for high grade prostate cancer, adjusted OR: 0.45 (95 % CI: 0.22–0.90), whereas a high intake of chocolate was positively associated with risk of total, advanced, localized and low grade disease (adjusted OR for total: 1.43, 95 % CI 1.12–1.82, advanced: 1.40, 95 % CI 1.01–1.96, localized: 1.43, 95 % CI 1.08–1.88, low-grade: 1.41, 95 % CI 1.03–1.93).

Conclusions

Total antioxidant intake from diet was not associated with prostate cancer risk. Supplement use may be associated with greater risk of disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2486-8) contains supplementary material, which is available to authorized users.

Consumption of whole grains and cereal fiber in relation to cancer risk: a systematic review of longitudinal studies

CONTEXT

Evidence from previous reviews is supportive of the hypothesis that whole grains may protect against various cancers. However, the reviews did not report risk estimates for both whole grains and cereal fiber and only case-control studies were evaluated. It is unclear whether longitudinal studies support this conclusion.

OBJECTIVE

To evaluate associations between whole grains and cereal fiber in relation to risk of lifestyle-related cancers data from longitudinal studies was evaluated.

DATA SOURCES

The following 3 databases were systematically searched: PubMed, EMBASE, and Cochrane CENTRAL.

STUDY SELECTION

A total of 43 longitudinal studies conducted in Europe and North America that reported multivariable-adjusted risk estimates for whole grains (n = 14), cereal fiber (n = 23), or both (n = 6) in relation to lifestyle-related cancers were included.

DATA EXTRACTION

Information on study location, cohort name, follow-up duration, sample characteristics, dietary assessment method, risk estimates, and confounders was extracted.

DATA SYNTHESIS

Of 20 studies examining whole grains and cancer, 6 studies reported a statistically significant 6%-47% reduction in risk, but 14 studies showed no association. Of 29 studies examining cereal fiber intake in relation to cancer, 8 showed a statistically significant 6%-49% reduction in risk, whereas 21 studies reported no association.

CONCLUSIONS

This systematic review concludes that most studies were suggestive of a null association. Whole grains and cereal fiber may protect against gastrointestinal cancers, but these findings require confirmation in additional studies.

Associations between fruit, vegetable and legume intakes and prostate cancer risk: results from the prospective Supplémentation en Vitamines et Minéraux Antioxydants (SU.VI.MAX) cohort

Although experimental studies suggest that fruits, vegetables and legumes may exert protective effects against prostate carcinogenesis through various bioactive compounds such as dietary fibre and antioxidants, epidemiological evidence is lacking. Notably, very few prospective studies have investigated the relationship between legume intake and prostate cancer risk. Our objective was to prospectively investigate the association between fruit, vegetable, tomato products, potatoes and legume intakes and prostate cancer risk. This study included 3313 male participants to the SUpplémentation en VItamines et Minéraux AntioXydants cohort (follow-up: 1994-2007) who completed at least three 24-h dietary records during the first 2 years of follow-up. Associations between tertiles of intake and prostate cancer risk were assessed by multivariate Cox proportional hazards models. After a median follow-up of 12·6 years, 139 incident prostate cancers were diagnosed. An inverse association was observed between prostate cancer risk and tertiles of legume intake (hazard ratio (HR)T3v.T1=0·53; 95 % CI 0·34, 0·85; P trend=0·009). This association was maintained after excluding soya and soya products from the legume group (HRT3 v.T1=0·56; 95 % CI 0·35, 0·89; P trend=0·02). No association was observed between prostate cancer risk and tertiles of intakes of fruits (P trend=0·25), vegetables (P trend=0·91), potatoes (P trend=0·77) and tomato products (P trend=0·09). This prospective study confirms the null association between fruit and non-starchy vegetable intakes and prostate cancer risk observed in most previous cohorts. In contrast, although very few prospective studies have been published on the topic, our results suggest an inverse association between legume intake and prostate cancer risk, supported by mechanistic plausibility. These results should be confirmed by large-scale observational and intervention studies.

Dietary resistant starch contained foods and breast cancer risk: a case-control study in northwest of Iran

BACKGROUND

A protective effect of resistant starch (RS) containing foods on carcinogenesis has been shown from several lines of experimental evidence for gastrointestinal cancers. Therefore, we aimed to investigate the association between RS contained foods and breast cancer (BC) risk in a hospital-based, age- and origin- matched, case-control study.

MATERIALS AND METHODS

A validated, semi-quantitative, food frequency questionnaire (FFQ) was completed by 306 women newly diagnosed with BC aged 25 to 65 years, and 309 healthy women as matched controls. Odds ratios (ORs) and 95% confidence intervals (95%CI) were estimated using conditional logistic regression models.

RESULTS

Reduced BC risk was associated with the highest tertile of whole-wheat bread and boiled potato consumption with adjusted ORs at 0.34 (95%CI: 0.19-0.59) and 0.61 (95%CI: 0.37- 0.99), respectively. Among consumers of whole-wheat bread consumers were considered, the protective role of cereals remained relatively apparent at higher intakes level of fiber rich breads at adjusted models (OR=0.53, 95%CI: 0.28-1.01). Moreover, high intake of legumes was found out to be a significant protective dietary factor against risk of BC development with an OR of 0.01 (95%CI: 0.03-0.13). However, consumption of white bread and biscuits was positively related to BC risk.

CONCLUSIONS

Our results show that certain RS containing foods, in particular whole wheat bread, legumes and boiled potato may reduce BC risk, whereas higher intake of white bread and biscuits may be related to increased BC risk.

The high prevalence of undiagnosed prostate cancer at autopsy: implications for epidemiology and treatment of prostate cancer in the Prostate-specific Antigen-era

Widespread prostate-specific antigen (PSA) screening detects many cancers that would have otherwise gone undiagnosed. To estimate the prevalence of unsuspected prostate cancer, we reviewed 19 studies of prostate cancer discovered at autopsy among 6,024 men. Among men aged 70-79, tumor was found in 36% of Caucasians and 51% of African-Americans. This enormous prevalence, coupled with the high sensitivity of PSA screening, has led to the marked increase in the apparent incidence of prostate cancer. The impact of PSA screening on clinical practice is well-recognized, but its effect on epidemiologic research is less appreciated. Before screening, a larger proportion of incident prostate cancers had lethal potential and were diagnosed at advanced stage. However, in the PSA era, overall incident prostate cancer mainly is indolent disease, and often reflects the propensity to be screened and biopsied. Studies must therefore focus on cancers with lethal potential, and include long follow-up to accommodate the lead time induced by screening. Moreover, risk factor patterns differ markedly for potentially lethal and indolent disease, suggesting separate etiologies and distinct disease entities. Studies of total incident or indolent prostate cancer are of limited clinical utility, and the main focus of research should be on prostate cancers of lethal potential.

Traditional Dietary Pattern Increases Risk of Prostate Cancer in Argentina: Results of a Multilevel Modeling and Bias Analysis from a Case-Control Study

There is increasing evidence that dietary habits play a role in prostate cancer (PC) occurrence. Argentinean cancer risk studies require additional attention because of the singular dietary pattern of this population. A case-control study (147 PC cases, 300 controls) was conducted in Córdoba (Argentina) throughout 2008-2013. A principal component factor analysis was performed to identify dietary patterns. A mixed logistic regression model was applied, taking into account family history of cancer. Possible bias was evaluated by probabilistic bias analysis. Four dietary patterns were identified: Traditional (fatty red meats, offal, processed meat, starchy vegetables, added sugars and sweets, candies, fats, and vegetable oils), Prudent (nonstarchy vegetables, whole grains), Carbohydrate (sodas/juices and bakery products), and Cheese (cheeses). High adherence to the Traditional (OR 2.82, 95%CI: 1.569-5.099) and Carbohydrate Patterns (OR 2.14, 95%CI: 1.470-3.128) showed a promoting effect for PC, whereas the Prudent and Cheese Patterns were independent factors. PC occurrence was also associated with family history of PC. Bias adjusted ORs indicate that the validity of the present study is acceptable. High adherence to characteristic Argentinean dietary patterns was associated with increased PC risk. Our results incorporate original contributions to knowledge about scenarios in South American dietary patterns and PC occurrence.

Dietary fiber, whole grains, carbohydrate, glycemic index, and glycemic load in relation to risk of prostate cancer

BACKGROUND

The relationships between dietary fiber, whole grains, carbohydrate, glycemic index (GI), glycemic load (GL), and prostate cancer risk are unclear. We conducted a systematic review and meta-analysis to investigate these associations.

METHODS

Relevant studies were identified by a search of PubMed database and EMBASE database up to April 2015. A random effects model was used to calculate the summary relative risks (RRs) and their corresponding 95% confidence intervals (CIs).

RESULTS

Twenty-seven epidemiological studies (18 case-control studies and nine cohort studies) were included in the final analysis. The pooled RRs of prostate cancer were 0.94 (95% CI 0.85-1.05, P=0.285), 1.13 (95% CI 0.98-1.30, P=0.095), 0.96 (95% CI 0.81-1.14, P=0.672), 1.06 (95% CI 0.96-1.18, P=0.254), and 1.04 (95% CI 0.91-1.18, P=0.590) for dietary fiber, whole grains, carbohydrate, GI, and GL, respectively. There was no evidence of significant publication bias based on the Begg's test and Egger's test.

CONCLUSION

The findings of this meta-analysis indicate that, based on available information, dietary fiber, whole grains, carbohydrate, GI, and GL are not associated with the risk of prostate cancer.

No association between fiber intake and prostate cancer risk: a meta-analysis of epidemiological studies

Background

The findings of epidemiologic studies on the association between fiber intake and prostate cancer risk remain conflicting. We aimed to examine this association by conducting a meta-analysis of epidemiological studies.

Methods

Relevant studies were identified by PubMed (1966 to March 2015) and Embase (1974 to March 2015) database search through March 2015. We included epidemiological studies that reported relative risks (RRs) or odds ratios (ORs) with 95 % confidence intervals (CIs) for the association between dietary fiber intake and prostate cancer risk. Random effects models were used to calculate the summary risk estimates.

Results

For the highest compared with the lowest dietary fiber intake, a significantly decreased risk with prostate cancer was observed in case-control studies (OR = 0.82; 95 % CI, 0.68–0.96), but not in cohort studies (RR = 0.94; 95 % CI, 0.77–1.11). The combined risk estimate of all studies was 0.89 (95 % CI, 0.77, 1.01). A significant heterogeneity was observed across studies (p = 0.005). There was no evidence of significant publication bias based on Begg’s funnel plot (p = 0.753) or Egger’s test (p = 0.946).

Conclusions

This meta-analysis suggests the absence of evidence for association between dietary fiber intake and prostate cancer risk.

Carbohydrate intake, glycemic index and prostate cancer risk

BACKGROUND

Reported associations between dietary carbohydrate and prostate cancer (PC) risk are poorly characterized by race.

METHODS

We analyzed the association between carbohydrate intake, glycemic index (GI), and PC risk in a study of white (N = 262) and black (N = 168) veterans at the Durham VA Hospital. Cases were 156 men with biopsy-confirmed PC and controls (N = 274) had a PSA test but were not recommended for biopsy. Diet was assessed before biopsy with a self-administered food frequency questionnaire. Logistic regression models were used to estimate PC risk.

RESULTS

In multivariable analyzes, higher carbohydrate intake, measured as percent of energy from carbohydrates, was associated with reduced PC risk (3rd vs. 1st tertile, OR = 0.41, 95% CI 0.21-0.81, P = 0.010), though this only reached significance in white men (p-trend = 0.029). GI was unrelated to PC risk among all men, but suggestively linked with reduced PC risk in white men (p-trend = 0.066) and increased PC risk in black men (p-trend = 0.172), however, the associations were not significant. Fiber intake was not associated with PC risk (all p-trends > 0.55). Higher carbohydrate intake was associated with reduced risk of high-grade (p-trend = 0.016), but not low-grade PC (p-trend = 0.593).

CONCLUSION

Higher carbohydrate intake may be associated with reduced risk of overall and high-grade PC. Future larger studies are needed to confirm these findings.

Fiber intake and risk of subsequent prostate cancer in Japanese men

BACKGROUND

Dietary fiber may reduce the risk of prostate cancer, possibly by increasing circulating concentrations of sex hormone-binding globulin and improving insulin sensitivity. However, results from previous epidemiologic studies of fiber intake and prostate cancer are inconsistent, and to our knowledge, no study has comprehensively evaluated the effects of soluble and insoluble fiber on prostate cancer in Asia.

OBJECTIVE

The objective was to examine the association between fiber intake and prostate cancer in Japanese men.

DESIGN

We conducted a population-based prospective study in 43,435 Japanese men aged 45-74 y. Participants responded to a validated questionnaire, which included 138 food items. Follow-up was from 1995 through 2009. HRs and 95% CIs of incidence were calculated according to quartiles of fiber intake.

RESULTS

During the 11.6-y follow-up, of the 825 men newly diagnosed with prostate cancer, 213 had advanced-stage cancer, 582 had organ-localized disease, and 30 had an undetermined stage of disease. Among them, 217 cases were detected by subjective symptoms. Total fiber was not associated with total or advanced prostate cancer, with respective multivariable HRs for the highest and lowest quartiles of 1.00 (95% CI: 0.77, 1.29; P-trend = 0.97) and 0.67 (95% CI: 0.42, 1.07; P-trend = 0.30). Total fiber and insoluble fiber intake were associated with a decreased risk of advanced cancers detected by subjective symptoms, with multivariate HRs (95% CIs) across increasing quartiles of 1.00, 0.58, 0.62, and 0.44 (0.21, 0.92; P-trend = 0.05) for total fiber and 1.00, 0.60, 0.52, and 0.46 (0.22, 0.93; P-trend = 0.04) for insoluble fiber. Soluble fiber intake showed no association with prostate cancer.

CONCLUSIONS

Dietary fiber is inversely associated with advanced prostate cancer detected by subjective symptoms even among populations with relatively low intake, such as Japanese. These results suggest that a very low intake of dietary fiber is associated with an increased risk of prostate cancer.

A high dietary glycemic index increases total mortality in a Mediterranean population at high cardiovascular risk

OBJECTIVE

Different types of carbohydrates have diverse glycemic response, thus glycemic index (GI) and glycemic load (GL) are used to assess this variation. The impact of dietary GI and GL in all-cause mortality is unknown. The objective of this study was to estimate the association between dietary GI and GL and risk of all-cause mortality in the PREDIMED study.

MATERIAL AND METHODS

The PREDIMED study is a randomized nutritional intervention trial for primary cardiovascular prevention based on community-dwelling men and women at high risk of cardiovascular disease. Dietary information was collected at baseline and yearly using a validated 137-item food frequency questionnaire (FFQ). We assigned GI values of each item by a 5-step methodology, using the International Tables of GI and GL Values. Deaths were ascertained through contact with families and general practitioners, review of medical records and consultation of the National Death Index. Cox regression models were used to estimate multivariable-adjusted hazard ratios (HR) and their 95% CI for mortality, according to quartiles of energy-adjusted dietary GI/GL. To assess repeated measures of exposure, we updated GI and GL intakes from the yearly FFQs and used Cox models with time-dependent exposures.

RESULTS

We followed 3,583 non-diabetic subjects (4.7 years of follow-up, 123 deaths). As compared to participants in the lowest quartile of baseline dietary GI, those in the highest quartile showed an increased risk of all-cause mortality [HR = 2.15 (95% CI: 1.15-4.04); P for trend  = 0.012]. In the repeated-measures analyses using as exposure the yearly updated information on GI, we observed a similar association. Dietary GL was associated with all-cause mortality only when subjects were younger than 75 years.

CONCLUSIONS

High dietary GI was positively associated with all-cause mortality in elderly population at high cardiovascular risk.

Utilization of a maltotetraose-producing amylase as a whole wheat bread improver: dough rheology and baking performance

A maltotetraose-producing enzyme (G4-amylase) was utilized to improve the baking performance of whole-grain wheat flour. Whole-grain bread dough prepared with G4-amylase showed reduced water absorption and increased development time, while the dough stability was not affected. Also, the G4-amylase-treated samples exhibited lower Mixolab torque values than the control upon heating and cooling. Rheological measurements showed the decreased ratio of Rmax /E and increased tan δ, clearly demonstrating that the viscous characteristics of whole-grain bread dough became dominant with increasing levels of G4-amylase. The use of G4-amylase produced whole-grain wheat breads with a variety of maltooligosaccharides, primarily maltotetraose that positively contributed to the bread volume (1.2-fold higher than the control). Moreover, G4-amylase delayed the crumb firming of whole-grain wheat bread during a 7-d storage period, showing that it can function as an antiretrogradation agent to enhance the quality attributes of whole-grain wheat bread.

Estimating insulin demand for protein-containing foods using the food insulin index

BACKGROUND/OBJECTIVE

The Food Insulin Index (FII) is a novel algorithm for ranking foods on the basis of insulin responses in healthy subjects relative to an isoenergetic reference food. Our aim was to compare postprandial glycemic responses in adults with type 1 diabetes who used both carbohydrate counting and the FII algorithm to estimate the insulin dosage for a variety of protein-containing foods.

SUBJECTS/METHODS

A total of 11 adults on insulin pump therapy consumed six individual foods (steak, battered fish, poached eggs, low-fat yoghurt, baked beans and peanuts) on two occasions in random order, with the insulin dose determined once by the FII algorithm and once with carbohydrate counting. Postprandial glycemia was measured in capillary blood glucose samples at 15-30  min intervals over 3 h. Researchers and participants were blinded to treatment.

RESULTS

Compared with carbohydrate counting, the FII algorithm significantly reduced the mean blood glucose level (5.7±0.2  vs 6.5±0.2 mmol/l, P=0.003) and the mean change in blood glucose level (-0.7±0.2 vs 0.1±0.2 mmol/l, P=0.001). Peak blood glucose was reached earlier using the FII algorithm than using carbohydrate counting (34±5 vs 56±7 min, P=0.007). The risk of hypoglycemia was similar in both treatments (48% vs 33% for FII vs carbohydrate counting, respectively, P=0.155).

CONCLUSIONS

In adults with type 1 diabetes, compared with carbohydrate counting, the novel FII algorithm improved postprandial hyperglycemia after consumption of protein-containing foods.

Dietary total and insoluble fiber intakes are inversely associated with prostate cancer risk

Although experimental data suggest a potentially protective involvement of dietary fiber in prostate carcinogenesis, very few prospective studies have investigated the relation between dietary fiber intake and prostate cancer risk, and those have had inconsistent results. Our objective was to study the association between dietary fiber intake (overall, insoluble, soluble, and from different sources, such as cereals, vegetables, fruits, and legumes) and prostate cancer risk. Stratifications by excess weight status, insulin-like growth factors, and amount of alcohol intake were also considered. This prospective analysis included 3313 men from the Supplémentation en Vitamines et Minéraux Antioxydants (SU.VI.MAX) cohort who completed at least 3 24-h dietary records. One hundred thirty-nine incident prostate cancers were diagnosed between 1994 and 2007 (median follow-up of 12.6 y). Associations between quartiles of energy-adjusted dietary fiber intake and prostate cancer risk were characterized by multivariate Cox proportional hazards models. Prostate cancer risk was inversely associated with total dietary fiber intake (HR of quartile 4 vs. quartile 1 = 0.47; 95% CI: 0.27, 0.81; P = 0.001), insoluble (HR = 0.46; 95% CI: 0.27, 0.78; P = 0.001), and legume (HR = 0.55; 95% CI: 0.32, 0.95; P = 0.04) fiber intakes. In contrast, we found no association between prostate cancer risk and soluble (P = 0.1), cereal (P = 0.7), vegetable (P = 0.9), and fruit (P = 0.4) fiber intakes. In conclusion, dietary fiber intake (total, insoluble, and from legumes but not soluble or from cereals, vegetables, and fruits) was inversely associated with prostate cancer risk, consistent with mechanistic data.

Diabetes and cancer: two diseases with obesity as a common risk factor

There is a growing body of evidence to support a connection between diabetes (predominantly type 2), obesity and cancer. Multiple meta-analyses of epidemiological data show that people with diabetes are at increased risk of developing many different types of cancers, along with an increased risk of cancer mortality. Several pathophysiological mechanisms for this relationship have been postulated, including insulin resistance and hyperinsulinaemia, enhanced inflammatory processes, dysregulation of sex hormone production and hyperglycaemia. In addition to these potential mechanisms, a number of common risk factors, including obesity, may be behind the association between diabetes and cancer. Indeed, obesity is associated with an increased risk of cancer and diabetes. Abdominal adiposity has been shown to play a role in creating a systemic pro-inflammatory environment, which could result in the development of both diabetes and cancer. Here, we examine the relationship between diabetes, obesity and cancer, and investigate the potential underlying causes of increased cancer risk in individuals with diabetes. Current treatment recommendations for reducing the overall disease burden are also explored and possible areas for future research are considered.

Plasma alkylresorcinol metabolites as biomarkers for whole-grain intake and their association with prostate cancer: a Swedish nested case-control study

BACKGROUND

Observational studies have mostly found no association between self-reported whole-grain intake and prostate cancer. Plasma alkylresorcinol metabolites have been suggested as biomarkers for whole-grain intake in free-living populations.

METHODS

We investigated the major dietary and lifestyle determinants of plasma alkylresorcinol metabolites in a nested case-control study (1,016 cases and 1,817 controls) in the Malmö Diet and Cancer Study. Multivariate adjusted ORs and 95% confidence intervals (95% CI) were estimated to assess the association between plasma alkylresorcinol metabolites and prostate cancer using logistic regression.

RESULTS

Whole-grain intake, waist circumference, educational level, and smoking status were the main determinants of alkylresorcinol metabolites. We observed significant correlations between alkylresorcinol metabolites and whole-grain (r = 0.31) and fiber (r = 0.27) intake. Metabolite concentration was positively associated with prostate cancer risk (Poverall effect = 0.0004) but the association was not linear (P = 0.04). The lowest risk was seen among men with moderate plasma concentrations. The OR for high compared with moderate plasma alkylresorcinol metabolites was 1.41 (95% CI, 1.10-1.80) for prostate cancer.

CONCLUSIONS

Results suggest that plasma alkylresorcinol metabolites are mainly determined by whole-grain intake in this nested case-control study of Swedish men. The increased risk of prostate cancer seen among men with high plasma alkylresorcinol metabolites requires further study, but residual confounding, detection bias, or competing risks of nonprostate cancer-related deaths are plausible explanations that could not be ruled out.

IMPACT

We found no evidence of a protective effect of whole grains on incident prostate cancer. Further validation of alkylresorcinol metabolites as a biomarker for whole-grain intake is needed.

Dietary cadmium intake and the risk of cancer: a meta-analysis

BACKGROUND

Diet is a major source of cadmium intake among the non-smoking general population. Recent studies have determined that cadmium exposure may produce adverse health effects at lower exposure levels than previously predicted. We conducted a meta-analysis to combine and analyze the results of previous studies that have investigated the association of dietary cadmium intake and cancer risk.

METHODS

We searched PubMed, EMBASE, and MEDLINE database for case-control and cohort studies that assessed the association of dietary cadmium intake and cancer risk. We performed a meta-analysis using eight eligible studies to summarize the data and summary relative risks (RRs) and 95% confidence intervals (CIs) were calculated using a random effects model.

RESULTS

Overall, dietary cadmium intake showed no statistically significant association with cancer risk (RR = 1.10; 95% CI: 0.99-1.22, for highest vs. lowest dietary cadmium group). However, there was strong evidence of heterogeneity, and subgroup analyses were conducted using the study design, geographical location, and cancer type. In subgroup analyses, the positive associations between dietary cadmium intake and cancer risk were observed among studies with Western populations (RR = 1.15; 95% CI: 1.08-1.23) and studies investigating some hormone-related cancers (prostate, breast, and endometrial cancers).

CONCLUSION

Our analysis found a positive association between dietary cadmium intake and cancer risk among studies conducted in Western countries, particularly with hormone-related cancers. Additional experimental and epidemiological studies are required to verify our findings.

Dietary patterns as predictors of prostate cancer in Jamaican men

Studies of diet and prostate cancer have focused primarily on food and nutrients; however, dietary patterns examine the overall diet, particularly foods eaten in combination, and risk of disease. We evaluated the association of dietary patterns and prostate cancer and low- and high-grade subgroups in Jamaican men. In a case-control study, we enrolled 243 incident cases and 273 urology controls in Jamaican clinics, March 2005-July 2007. Dietary patterns were identified using principal component analysis. Four food patterns were identified: a "vegetable and legume" pattern, a "fast food" pattern, a "meat" pattern, and a "refined carbohydrate" pattern. Men in the highest tertile for the refined carbohydrate pattern, characterized by high intakes of rice, pasta, sugar sweetened beverages, and sweet baked foods were at increased risk of total prostate cancer [odds ratio (OR) = 2.02; 95% confidence interval (CI) = 1.05-3.87 (Ptrend = 0.029)] and low-grade disease [OR = 2.91; 95% CI = 1.18-7.13 (Ptrend = 0.019)] compared with men in the lowest tertile. The vegetable and legumes pattern (healthy), meat pattern, or fast food pattern were not associated with prostate cancer risk. These data suggest a carbohydrate dietary pattern high in refined carbohydrates may be a risk factor for prostate cancer in Jamaican men.

Case-control and prospective studies of dietary α-linolenic acid intake and prostate cancer risk: a meta-analysis

OBJECTIVE

α-Linolenic acid (ALA) is considered to be a cardioprotective nutrient; however, some epidemiological studies have suggested that dietary ALA intake increases the risk of prostate cancer. The main objective was to conduct a systematic review and meta-analysis of case-control and prospective studies investigating the association between dietary ALA intake and prostate cancer risk.

DESIGN

A systematic review and meta-analysis were conducted by searching MEDLINE and EMBASE for relevant prospective and case-control studies.

INCLUDED STUDIES

We included all prospective cohort, case-control, nested case-cohort and nested case-control studies that investigated the effect of dietary ALA intake on the incidence (or diagnosis) of prostate cancer and provided relative risk (RR), HR or OR estimates.

PRIMARY OUTCOME MEASURE

Data were pooled using the generic inverse variance method with a random effects model from studies that compared the highest ALA quantile with the lowest ALA quantile. Risk estimates were expressed as RR with 95% CIs. Heterogeneity was assessed by χ(2) and quantified by I(2).

RESULTS

Data from five prospective and seven case-control studies were pooled. The overall RR estimate showed ALA intake to be positively but non-significantly associated with prostate cancer risk (1.08 (0.90 to 1.29), p=0.40; I(2)=85%), but the interpretation was complicated by evidence of heterogeneity not explained by study design. A weak, non-significant protective effect of ALA intake on prostate cancer risk in the prospective studies became significant (0.91 (0.83 to 0.99), p=0.02) without evidence of heterogeneity (I(2)=8%, p=0.35) on removal of one study during sensitivity analyses.

CONCLUSIONS

This analysis failed to confirm an association between dietary ALA intake and prostate cancer risk. Larger and longer observational and interventional studies are needed to define the role of ALA and prostate cancer.

Dietary intakes of carbohydrates in relation to prostate cancer risk: a prospective study in the Malmö Diet and Cancer cohort

BACKGROUND

Dietary carbohydrates have been implicated in relation to prostate cancer.

OBJECTIVE

Our objective was to examine the associations between dietary intakes of carbohydrates, fiber, and their food sources and risk of prostate cancer, overall and by case severity, in the Malmö Diet and Cancer cohort.

DESIGN

The analysis included 8128 men aged 45-73 y without a history of cancer, cardiovascular disease, or diabetes and who were classified as adequate energy reporters. After a median follow-up time of 15 y, prostate cancer was diagnosed in 817 men. We used Cox proportional hazards regression to model associations between energy-adjusted nutrient and food intakes with risk of incident prostate cancer, with competing risk of death from non-prostate cancer causes taken into account.

RESULTS

After adjustment for age and other known or potential risk factors, we observed no associations between total carbohydrates or dietary fiber and prostate cancer. We observed positive associations between the intake of low-fiber cereals with overall and low-risk prostate cancer and between intakes of cake and biscuits and rice and pasta with low-risk prostate cancer (all P-trend < 0.05). A high intake compared with zero consumption of sugar-sweetened beverages was associated with increased risk of symptomatic prostate cancer (HR: 1.38; 95% CI: 1.04, 1.84).

CONCLUSIONS

Results from this large study with high-validity dietary data suggest that a high intake of refined carbohydrates may be associated with increased risk of prostate cancer. However we observed no significant associations with high-risk prostate cancer, and not all foods that are typically high in refined carbohydrates were associated with prostate cancer.

Intake of grains and dietary fiber and prostate cancer aggressiveness by race

Purpose. To examine the associations among intake of refined grains, whole grains and dietary fiber and aggressiveness of prostate cancer in African Americans (AA, n = 930) and European Americans (EA, n = 993) in a population-based, case-only study (The North Carolina-Louisiana Prostate Cancer Project, PCaP). Methods. Prostate cancer aggressiveness was categorized as high, intermediate or low based on Gleason grade, PSA level and clinical stage. Dietary intake was assessed utilizing the NCI Diet History Questionnaire. Logistic regression (comparing high to intermediate/low aggressive cancers) and polytomous regression with adjustment for potential confounders were used to determine odds of high prostate cancer aggressiveness with intake of refined grains, whole grains and dietary fiber from all sources. Results. An inverse association with aggressive prostate cancer was observed in the 2nd and 3rd tertiles of total fiber intake (OR = 0.70; 95% CI, 0.50–0.97 and OR = 0.61; 95% CI, 0.40–0.93, resp.) as compared to the lowest tertile of intake. In the race-stratified analyses, inverse associations were observed in the 3rd tertile of total fiber intake for EA (OR = 0.44; 95% CI, 0.23–0.87) and the 2nd tertile of intake for AA (OR = 0.57; 95% CI, 0.35–0.95). Conclusions. Dietary fiber intake was inversely associated with aggressive prostate cancer among both AA and EA men.

Glycaemic index and glycaemic load in relation to risk of diabetes-related cancers: a meta-analysis

Diets high in glycaemic index (GI) or glycaemic load (GL) have been hypothesised to increase the risks of certain cancers by increasing blood glucose or insulin concentrations. We aimed to conduct a meta-analysis of prospective cohort studies to evaluate the association between GI or GL and diabetes-related cancers (DRC), including bladder, breast, colon-rectum, endometrium, liver and pancreas, which are associated with an increased risk for diabetes, and prostate cancer, which is associated with a reduced risk for diabetes. We searched Pubmed, EMBASE and MEDLINE databases up to September 2011 and reference lists of relevant articles. Relative risks (RR) and 95 % CI for the highest v. the lowest categories were extracted and pooled using a random-effects model. Thirty-six prospective cohort studies with a total of 60 811 DRC cases were included in the present meta-analysis. In a comparison of the highest and lowest categories, the pooled RR of DRC were 1·07 (95 % CI 1·04, 1·11; n 30) for GI and 1·02 (95 % CI 0·96, 1·08; n 33) for GL. In an analysis of site-specific cancer risks, we found significant associations for GI in relation to breast cancer (RR 1·06; 95 % CI 1·02, 1·11; n 11) and colorectal cancer (RR 1·08; 95 % CI 1·00, 1·17; n 9 studies). GL was significantly associated with the risk of endometrial cancer (RR 1·21; 95 % CI 1·07, 1·37; n 5). In conclusion, the findings of the present study suggest a modest-to-weak association between a diet that induces a high glucose response and DRC risks.