Dietary glycaemic index, glycaemic load and breast cancer risk: a systematic review and meta-analysis

Gut microbiota in diabetic-linked polycystic ovarian syndrome: Mechanisms and therapeutic insights

Polycystic ovarian syndrome (PCOS) is a complex multisystem disorder prevalent among women of reproductive age, commonly marked by insulin resistance, hyperinsulinemia, and metabolic disruptions such as hypertension and dyslipidemia, which elevate risks of cardiovascular disease and hepatic steatosis. Recent advances underscore the gut microbiome's critical role in modulating insulin resistance and metabolic homeostasis in PCOS. This review highlights novel insights into gut dysbiosis-driven inflammation, gut-brain hormonal signaling, and immune modulation as underlying mechanisms connecting PCOS with metabolic dysfunction and diabetes. We comprehensively analyzed studies up to September 2024 on gut microbiota, diabetes, PCOS, and metformin, exploring emerging perspectives on the microbiome's therapeutic potential in managing PCOS. Metformin's dual role in insulin sensitivity improvement and gut microbiome modulation is emphasized, including its indirect effects on weight management. This review also identifies gaps in current research, urging a shift toward precision therapies targeting microbiome-related pathways in PCOS. Further exploration of the gut-brain axis, pathogen-associated molecular patterns, and the need for controlled clinical trials are discussed to enhance therapeutic approaches.

Dietary Glycemic Index, Glycemic Load, Sugar, and Fiber Intake in Association With Breast Cancer Risk: An Updated Meta-analysis

CONTEXT

Several prospective cohort studies have investigated the association between glycemic index (GI), glycemic load (GL), dietary sugar, and total dietary fiber intake, with female breast cancer (BC) risk and reported inconsistent results. In the last decade, several large epidemiological studies have investigated these associations, suggesting the need to revisit the current body of evidence.

OBJECTIVE

The aim of this study was to update a systematic review and meta-analysis conducted by Schlesinger et al in 2017 using recent scientific evidence published since 2015.

DATA SOURCES

Publications indexed in PubMed, Embase, and The Cochrane Library were retrieved from the inception of the database up to January 2024.

DATA EXTRACTION

Two reviewers independently extracted data and assessed each study's quality.

DATA ANALYSIS

A random-effects model was used to estimate summary risk ratios (RRs) and 95% CIs for a meta-analysis that included 33 publications, with 26 prospective cohort studies cumulatively enrolling 2 212 645 women, among whom 79 777 were diagnosed with incident BC.

RESULTS

Dietary GI and GL (highest vs lowest exposure intake) were both associated with 5% higher BC risk-RR (95% CI): 1.05 (1.01-1.09; P = .007) and 1.05 (0.97-1.13; P = .24), respectively. No clear associations were observed for sugar and total dietary fiber intake (highest vs lowest exposure intake)-RR (95% CI): 1.12 (0.95-1.11; P = .16) and 0.93 (0.86-1.00; P = .05), respectively. For the latter, the association was more pronounced among premenopausal women (RR: 0.78; 95% CI: 0.68-0.90; P = .0008).

CONCLUSION

This meta-analysis supports a significant positive association between high dietary GI intake and higher risk of BC and a significant inverse association between high dietary fiber intake and lower risk of BC. Interventions promoting a high-fiber and low-sugar diet may be useful components of BC-prevention strategies.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42023463143.

Associations Between Dietary Factors and Breast Cancer Risk: A Systematic Review of Evidence from the MENA Region

BACKGROUND

The Middle East and North Africa (MENA) region is witnessing a continuous rise in the incidence of breast cancer (BC). This region is characterized by distinct cultural and lifestyle habits. Despite the importance of diet as a modifiable risk factor for BC, its role in the development of BC within the MENA context has not been extensively studied. This systematic review aims to identify and synthesize existing evidence regarding the effect of different dietary factors on BC risk among women from this region.

METHODS

We systematically reviewed the scientific literature for observational studies that examined the association between specific dietary factors and the risk of BC in MENA, in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Our comprehensive search included databases such as PubMed, Web of Science, ScienceDirect, and Scopus, identified a total of 18,085 records, of which 65 met our inclusion criteria and were assessed for quality using the National Institute of Health Quality Assessment Tool.

RESULTS

The findings of the 65 included studies were categorized into food groups, nutrients, and dietary patterns. Studies in the MENA region have consistently shown that the consumption of fruit and vegetables, fish and seafood, and black tea are associated with a reduced BC risk. In contrast, the intake of milk and white bread is linked to an increased risk. Specific dietary patterns such as the Mediterranean diet, a healthy plant-based diet, dietary antioxidant index, and overall healthy dietary patterns have shown a negative association with BC risk. Conversely, the dietary insulin index and load, dietary glycemic index, dietary inflammatory index, and unhealthy dietary patterns are associated with an increased risk of BC. For the remaining dietary factors, research was too limited or inconsistent to draw conclusions.

CONCLUSIONS

Our findings highlight the significant role of dietary factors in modulating BC risk among women in the MENA region, an area that faces a notable gap in research on this topic. Further studies are essential to deepen our understanding and develop targeted dietary recommendations for BC prevention in this population.

Causes and Risk Factors of Breast Cancer, What Do We Know for Sure? An Evidence Synthesis of Systematic Reviews and Meta-Analyses

Breast cancer affected more than 2.3 million women in 2022 and is the most diagnosed cancer among women worldwide. The incidence rates are greater in developed regions and are significantly higher among women with higher education and socioeconomic status. Therefore, it is reasonable to assume that the way women live their lives may impact their risk of being diagnosed with breast cancer. This systematic review aimed to identify what is known about the causes and risk factors of breast cancer, excluding genetic causes. A comprehensive systematic search identified 2387 systematic reviews, 122 were included and six overall themes identified. In our "top list" with the 36 most important findings, a study of breast density had the highest effect size for increasing the risk of breast cancer, and a high sex-hormone-binding globulin level was the most protective factor. Many of the included studies investigating the same topics had conflicting results. The conclusion from this evidence synthesis reveals a lack of consensus of factors associated with the causes and risk of breast cancer. These findings suggest that recommendations about lifestyle and breast cancer should be made with caution.

Review of Mendelian Randomization Studies on Endometrial Cancer

Endometrial cancer (EC) is a common gynecological cancer. In some parts of the world, the incidence and mortality of EC are on the rise. Understanding the risk factors of EC is necessary to prevent the occurrence of this disease. Observational studies have revealed the association between certain modifiable environmental risk factors and EC risk. However, due to unmeasured confounding, measurement errors, and reverse causality, observational studies sometimes have limited ability to judge robust causal inferences. In recent years, Mendelian randomization (MR) analysis has received extensive attention, providing valuable insights for cancer-related research, and is expected to identify potential therapeutic interventions. In MR analysis, genetic variation (alleles are randomly assigned during meiosis and are usually independent of environmental or lifestyle factors) is used instead of modifiable exposure to study the relationship between risk factors and disease. Therefore, MR analysis can make causal inference about exposure and disease risk. This review briefly describes the key principles and assumptions of MR analysis; summarizes published MR studies on EC; focuses on the correlation between different risk factors and EC risks; and discusses the application of MR methods in EC research. The results of MR studies on EC showed that type 2 diabetes, uterine fibroids, higher body mass index, higher plasminogen activator inhibitor-1 (PAI-1), higher fasting insulin, early insulin secretion, longer telomere length, higher testosterone and higher plasma cortisol levels are associated with increased risk of EC. In contrast, later age of menarche, higher circulatory tumor necrosis factor, higher low-density lipoprotein cholesterol, and higher sex hormone-binding globulin levels are associated with reduced risk of EC. In general, despite some limitations, MR analysis still provides an effective way to explore the causal relationship between different risk factors and EC.

Dietary carbohydrate quality and risk of breast cancer among women

Background

A few studies have examined the relationship between carbohydrate quality index (CQI) and risk of breast cancer (BC) among women in Middle Eastern countries. We studied the associations between carbohydrate quality index and the risk of BC in overall and by menopausal status.

Methods

In this case-control study, dietary intake of 461 women with pathologically confirmed BC within the past year were examined. The same information were collected for 495 apparently healthy controls using a 168-item validated FFQ. Carbohydrate quality was determined by considering four criteria including: ratio of solid carbohydrates to total carbohydrates, dietary fiber intake, GI and the ratio of whole grains to total grains.

Results

Mean GI and GL of participants were totally 57.5 ± 7.2 and 245.7 ± 64.7, respectively. A trend toward significant association was seen between GI and odds of BC in the whole population; such that after stratifying analysis by menopausal status, premenopausal women in the highest quartile of GI were 1.85 times higher likely to have BC than those in the lowest quartile (95% CI: 1.12, 3.07, P = 0.01). We found that women with the greatest CQI had lower odds for BC, compared with those with the lowest CQI (0.63; 95% CI: 0.43–0.94, P = 0.03). This association was remained after stratifying analysis by menopausal status in premenopausal (0.55; 95% CI: 0.34–0.90, P = 0.04).

Conclusion

We found that GI was directly and CQI inversely associated with odds of BC. In order to determine the effects of dietary carbohydrate quality prospective cohort studies are needed.

Sugar-Sweetened Soda Consumption and Total and Breast Cancer Mortality: The Western New York Exposures and Breast Cancer (WEB) Study

BACKGROUND

There is growing evidence of an association between sugar-sweetened beverages (SSB) and increased risk of mortality in various populations. However, SSB influence on mortality among patients with breast cancer is unknown.

METHODS

We assessed the relationship between sugar-sweetened soda and both all-cause and breast cancer mortality among women with incident, invasive breast cancer from the Western New York Exposures and Breast Cancer Study. Breast cancer cases were followed for a median of 18.7 years, with ascertainment of vital status via the National Death Index. Frequency of sugar-sweetened soda consumption was determined via dietary recall using a food frequency questionnaire. Cox proportional hazards, adjusting for relevant variables, were used to estimate HRs and 95% confidence intervals (CI).

RESULTS

Of the 927 breast cancer cases, 386 (54.7%) had died by the end of follow-up. Compared with never/rarely sugar-sweetened soda drinkers, consumption at ≥5 times per week was associated with increased risk of both total (HR = 1.62; 95% CI, 1.16-2.26; P _trend < 0.01) and breast cancer mortality (HR = 1.85; 95% CI, 1.16-2.94; P _trend < 0.01). Risk of mortality was similarly increased among ER-positive, but not ER-negative patients; among women with body mass index above the median, but not below the median; and among premenopausal, but not postmenopausal women for total mortality only.

CONCLUSIONS

Reported higher frequency of sugar-sweetened soda intake was associated with increased risks of both total and breast cancer mortality among patients with breast cancer.

IMPACT

These results support existing guidelines on reducing consumption of SSB, including for women with a diagnosis of breast cancer.

Breast Cancer Primary Prevention and Diet: An Umbrella Review

Introduction: Many studies have been published, but none have pooled the useful evidence available in the literature to produce guidelines and health policies promoting healthy eating styles to prevent breast cancer (BC). The present study aimed to summarize the evidence produced to date, taking a judicious, critical approach to the quality of the studies analyzed. Methods: An umbrella review method was adopted, which is a systematic review of second-level studies, meta-analyses and literature reviews. Results: In all, 48 studies were considered: 32 meta-analyses, 4 pooled analyses, 5 systematic reviews, and 7 qualitative reviews. A higher intake of total meat, or red or processed meats, or foods with a high glycemic index, or eggs would seem to be associated with a higher risk of BC. Some foods, such as vegetables, would seem instead to have an inverse association with BC risk. One meta-analysis revealed an inverse association between citrus fruit and mushroom consumption and BC. Some nutrients, such as calcium, folate, vitamin D, lignans and carotenoids, also seem to be inversely associated with BC risk. The evidence is still conflicting as concerns exposure to other dietary elements (e.g., polyunsaturated fatty acids, dairy foods). Conclusion: Nutrition is one of the most modifiable aspects of people's lifestyles and dietary choices can affect health and the risk of cancer. Overall, adhering to a healthy eating style may be associated with a significant reduction in the risk of BC.

Glycemic Index, Glycemic Load and Cancer Risk: An Updated Meta-Analysis

Diets high in glycemic index (GI) and glycemic load (GL) have been related to an increased risk of selected cancers, but additional quantification is required. We updated a systematic review and meta-analysis published in 2015 to May 2019 to provide quantitative information on GI/GL and cancer risk. Relative risks (RR) and the corresponding 95 % confidence intervals (CI) for the highest versus the lowest categories of GI and GL were extracted from selected studies and pooled using random-effects models. Twenty reports (>22,000 cancer cases) have become available after January 2015, and 15 were added to the meta-analyses by cancer sites, which considered a total of 88 investigations. The five additional reports were reviewed, but not included in the meta-analyses, since data were inadequate to be pooled. For hormone-related cancers, summary RRs for the highest versus lowest GI and GL intakes were moderately increased. They ranged from 1.04 (breast) to 1.12 (endometrium) for GI and from 1.03 (prostate) to 1.22 (ovary) for GL, of borderline significance. High GI was associated with small increased risks of colorectal (summary RR for GI: 1.20, 95% CI, 1.07–1.34—GL: 1.09, 95% CI, 0.97–1.22, 19 studies), bladder (GI: 1.25, 95% CI, 1.11–1.41—GL: 1.10, 95% CI, 0.85–1.42, four studies) and kidney cancers (GI: 1.16, 95% CI, 1.02–1.32—GL: 1.14, 95% CI, 0.81–1.60, five studies). GL was not significantly related to those cancer sites. Stomach, prostate and lung cancers were not associated with GI and GL. The present analysis, based on an updated comprehensive evaluation of the epidemiological literature, indicates moderate unfavorable effects of high versus low GI on colorectal, and possibly bladder and kidney cancers, and a possible moderate positive association between GL and endometrial cancer.

Carbohydrate Nutrition and the Risk of Cancer

PURPOSE OF REVIEW

This review summarizes a selection of epidemiologic research assessing the associations between carbohydrate intake and cancer incidence and survival. Evidence for plausible biological mechanisms is also considered.

RECENT FINDINGS

The mechanistic paradigm explaining the relationship between carbohydrates and cancer risk has been contested by numerous observational studies. Carbohydrates have conventionally been ascribed a deleterious role in the field of cancer research due to previous preclinical findings. A breadth of studies suggests that complex carbohydrate intake is inversely associated with risk of a number of cancer types. Data from studies assessing simple carbohydrates and cancer risk are mixed. Furthermore, recommendations for subsequent studies are framed.

Nutrition and Breast Cancer: A Literature Review on Prevention, Treatment and Recurrence

Breast cancer (BC) is the second most common cancer worldwide and the most commonly occurring malignancy in women. There is growing evidence that lifestyle factors, including diet, body weight and physical activity, may be associated with higher BC risk. However, the effect of dietary factors on BC recurrence and mortality is not clearly understood. Here, we provide an overview of the current evidence obtained from the PubMed databases in the last decade, assessing dietary patterns, as well as the consumption of specific food-stuffs/food-nutrients, in relation to BC incidence, recurrence and survival. Data from the published literature suggest that a healthy dietary pattern characterized by high intake of unrefined cereals, vegetables, fruit, nuts and olive oil, and a moderate/low consumption of saturated fatty acids and red meat, might improve overall survival after diagnosis of BC. BC patients undergoing chemotherapy and/or radiotherapy experience a variety of symptoms that worsen patient quality of life. Studies investigating nutritional interventions during BC treatment have shown that nutritional counselling and supplementation with some dietary constituents, such as EPA and/or DHA, might be useful in limiting drug-induced side effects, as well as in enhancing therapeutic efficacy. Therefore, nutritional intervention in BC patients may be considered an integral part of the multimodal therapeutic approach. However, further research utilizing dietary interventions in large clinical trials is required to definitively establish effective interventions in these patients, to improve long-term survival and quality of life.

Epidemiology of Breast Cancer in Women

Epidemiologic studies have contributed importantly to current knowledge of environmental and genetic risk factors for breast cancer. Worldwide, breast cancer is an important cause of human suffering and premature mortality among women. In the United States, breast cancer accounts for more cancer deaths in women than any site other than lung cancer. A variety of risk factors for breast cancer have been well-established by epidemiologic studies including race, ethnicity, family history of cancer, and genetic traits, as well as modifiable exposures such as increased alcohol consumption, physical inactivity, exogenous hormones, and certain female reproductive factors. Younger age at menarche, parity, and older age at first full-term pregnancy may influence breast cancer risk through long-term effects on sex hormone levels or by other biological mechanisms. Recent studies have suggested that triple negative breast cancers may have a distinct etiology. Genetic variants and mutations in genes that code for proteins having a role in DNA repair pathways and the homologous recombination of DNA double stranded breaks (APEX1, BRCA1, BRCA2, XRCC2, XRCC3, ATM, CHEK2, PALB2, RAD51, XPD), have been implicated in some cases of breast cancer.

Carbohydrates, glycemic index, glycemic load, and breast cancer risk: a systematic review and dose-response meta-analysis of prospective studies

Context

The investigation of dose-response associations between carbohydrate intake, glycemic index, glycemic load, and risk of breast cancer stratified by menopausal status, hormone receptor status, and body mass index (BMI) remains inconclusive.

Objective

A systematic review and dose-response meta-analyses was conducted to investigate these associations.

Data Sources

As part of the World Cancer Research Fund/American Institute for Cancer Research Continuous Update Project, PubMed was searched up to May 2015 for relevant studies on these associations.

Study Selection

Prospective studies reporting associations between carbohydrate intake, glycemic index, or glycemic load and breast cancer risk were included.

Data Extraction

Two investigators independently extracted data from included studies.

Results

Random-effects models were used to summarize relative risks (RRs) and 95%CIs. Heterogeneity between subgroups, including menopausal status, hormone receptor status, and BMI was explored using meta-regression. Nineteen publications were included. The summary RRs (95%CIs) for breast cancer were 1.04 (1.00-1.07) per 10 units/d for glycemic index, 1.01 (0.98-1.04) per 50 units/d for glycemic load, and 1.00 (0.96-1.05) per 50 g/d for carbohydrate intake. For glycemic index, the association appeared slightly stronger among postmenopausal women (summary RR per 10 units/d, 1.06; 95%CI, 1.02-1.10) than among premenopausal women, though the difference was not statistically significant (Pheterogeneity = 0.15). Glycemic load and carbohydrate intake were positively associated with breast cancer among postmenopausal women with estrogen-negative tumors (summary RR for glycemic load, 1.28; 95%CI, 1.08-1.52; and summary RR for carbohydrates, 1.13; 95%CI, 1.02-1.25). No differences in BMI were detected.

Conclusions

Menopausal and hormone receptor status, but not BMI, might be potential influencing factors for the associations between carbohydrate intake, glycemic index, glycemic load, and breast cancer.

Dietary glycemic index, glycemic load and cancer: An overview of the literature

AIMS

The aim of this paper is to provide an overview of the current evidence for associations between dietary glycemic index (GI) and dietary glycemic load (GL), and the risk of various types of cancer, and to summarize mechanisms proposed to explain the associations found.

DATA SYNTHESIS

Medline was searched for cohort studies, case-control studies, and meta-analyses, published up to February 2016, that examined associations between dietary GI/GL and cancer. Findings from the main meta-analyses showed a weak-to-moderate association of high dietary GI/GL with increased risk of some cancers. High dietary GI but not GL was significantly and consistently associated with increased colorectal cancer risk in both cohort and case-control studies. Dietary GL was directly associated with breast and endometrial cancer risk in cohort studies. Positive associations between dietary GI or GL and cancer risk were found more frequently in case-control studies than cohort studies. The main mechanism for these associations is thought to be chronic hyperinsulinemia. Insulin is itself a mitogen and also increases the bioactivity of insulin-like growth factors which can promote cancer by inhibiting apoptosis and stimulating cell proliferation.

CONCLUSIONS

The review has uncovered consistent evidence that high dietary GI is associated with increased risk of colorectal cancer, and that high dietary GL is associated with increased risk of breast and endometrial cancer. However the risk increases are small or moderate.

Addressing the Role of Obesity in Endometrial Cancer Risk, Prevention, and Treatment

In sharp contrast to many other cancer types, the incidence and mortality of endometrial cancer continue to grow. This unfortunate trend is, in no small part, a result of the worldwide obesity epidemic. More than half of endometrial cancers are currently attributable to obesity, which is recognized as an independent risk factor for this disease. In this review, we identify the molecular mechanisms by which obesity and adipose tissue contribute to the pathogenesis of endometrial cancer. We further discuss the impact of obesity on the clinical management of the disease and examine the development of rational behavioral and pharmaceutical interventions aimed at reducing endometrial cancer risk, improving cancer outcomes, and preserving fertility in an increasingly younger population of patients with endometrial 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.

TCF7L2 type 2 diabetes risk variant, lifestyle factors, and incidence of prostate cancer

BACKGROUND

Variation in transcription factor 7-like 2 (TCF7L2), the strongest genetic risk factor for type 2 diabetes (T2D), may play a role in prostate cancer (PCa) depending on lifestyle factors. The aims of this study were to determine if TCF7L2 rs7903146 is associated with risk of PCa and if the association is modified by lifestyle factors independently of T2D status.

METHODS

We prospectively followed 8,558 men in the Malmö Diet and Cancer Study from baseline 1991-1996 until end of 2009. Cox regression models were used to assess the association between rs7903146 T2D-risk allele (T) and PCa. Effect modification by incident T2D status, fasting glucose levels, dietary, and lifestyle risk factors were tested.

RESULTS

During follow-up 855 incident PCa cases were registered. We observed a non-significant tendency for the TCF7L2 variant to associate with higher risk of PCa, which was unaffected by adjustment for incident T2D (HR = 1.24; 95% CI: 0.96, 1.60; P = 0.079) but more pronounced among subjects who developed T2D (HR = 1.91, 95% CI: 0.88, 4.14; P = 0.064). In a sub-sample of hyperglycemic men we observed an increased risk of PCa among T-allele carriers (HR = 2.72, 95% CI: 1.22, 6.04; P = 0.014; P(interaction)  = 0.056). T-allele carriers with higher number of lifestyle risk factors had an increased risk of PCa (P(interaction)  = 0.006).

CONCLUSIONS

We found no independent association between TCF7L2 rs7903146 and PCa risk. However, among hyperglycemic men we observed that the risk allele may increase risk of PCa. The association between rs7903146 and PCa risk may also be modified by lifestyle factors.

Nutrient pathways and breast cancer risk: the Long Island Breast Cancer Study Project

The relative importance of biochemical pathways has not been previously examined when considering the influence of diet on breast cancer risk. To address this issue, we used interview data from a population-based sample of 1463 breast cancer cases and 1500 controls. Dietary intake was assessed shortly after diagnosis using a 101-item food frequency questionnaire. Age- and energy-adjusted odds ratios (ORs) for individual micro- and macronutrients were estimated with logistic regression. Hierarchical modeling was used to account for biologically plausible nutrient pathways (1-carbon metabolism, oxidative stress, glycemic control, and phytoestrogens). Effect estimates from hierarchical modeling were more precise and plausible compared to those from multivariable models. The strongest relationship observed was for the glycemic control pathway, but confidence intervals (CI) were wide [OR (95% CI): 0.86 (0.62, 1.21)]. Little or no effect was observed for the 1-carbon metabolism, oxidative stress, and phytoestrogen pathways. Associations were similar when stratified by supplement use. Our approach that emphasizes biochemical pathways, rather than individual nutrients, revealed that breast cancer risk may be more strongly associated with glycemic control factors than those from other pathways considered. Our study emphasizes the importance of accounting for multiple nutrient pathways when examining associations between dietary intake and breast cancer.

Glycemic index, glycemic load and mammographic breast density: the EPIC Florence longitudinal study

A few studies have evaluated the association between diet and mammographic breast density (MBD) and results are inconsistent. MBD, a well-recognized risk factor for breast cancer, has been proposed as a marker of cumulative exposure to hormones and growth factors. Diets with a high glycemic index (GI) or glycemic load (GL) may increase breast cancer risk, via an effect on the insulin-like growth factor axis. We have investigated the association between carbohydrate intake, GI, GL and MBD in a prospective study. We identified a large series of women, in the frame of the EPIC-Florence cohort, with a mammogram taken five years after enrolment, when detailed information on dietary and lifestyle habits and anthropometric measurements had been collected. Mammograms have been retrieved (1,668, 83%) and MBD assessed according to Wolfe's classification. We compared women with high MBD (P2+DY Wolfe's categories) with those with low MBD (N1+P1) through logistic models adjusted for age, education, body mass index, menopause, number of children, breast feeding, physical activity, non-alcohol energy, fibers, saturated fat and alcohol. A direct association between GL and high MBD emerged in the highest quintile of intake in comparison with the lowest quintile (OR = 1.73, 95%CI 1.13-2.67, p for trend = 0.048) while no association with glycemic index was evident. These results were confirmed after exclusion of women reporting to be on a diet or affected with diabetes, and when Hormone Replacement Therapy at the date of mammographic examination used to assess MBD was considered. The effect was particularly evident among leaner women, although no interaction was found. A positive association was suggested for increasing simple sugar and total carbohydrates intakes limited to the highest quintiles. In this Italian population we observed an association between glycemic load, total and rapidly absorbed carbohydrates and high MBD. These novel results warrant further investigations.

High glycemic diet and breast cancer occurrence in the Italian EPIC cohort

BACKGROUND AND AIMS

There are theoretical reasons for suspecting that a high glycemic index (GI) or glycemic load (GL) diet may increase breast cancer risk, perhaps via an effect on the insulin-like growth factor (IGF) axis. However observational studies have produced inconsistent findings and it is controversial whether breast cancer risk is influenced by the carbohydrate characteristics of the diet. We prospectively investigated the association between dietary GI and GL and breast cancer in the Italian section of the European Prospective Investigation into Cancer and Nutrition (EPIC).

METHODS AND RESULTS

Women were recruited from 1993 to 1998 at five centers: Varese and Turin (north Italy), Florence (central Italy), and Ragusa and Naples (south Italy). Participants completed validated food frequency questionnaires from which GI and GL were estimated. Multivariable Cox proportional hazard regression models quantified the association between breast cancer risk and total carbohydrate intake, GI, and GL. During 11 years of follow-up, 879 breast cancer (797 invasive and 82 in situ) cases were indentified. High dietary GL was associated with increased breast cancer risk (RR 1.45, 95% CI = 1.06-1.99; highest vs. lowest quintile; p-trend 0.029), whereas dietary GI and total carbohydrate had no influence. The association was not modified by menopausal status or body mass index.

CONCLUSION

Our data indicate that, in a Mediterranean population characterized by traditionally high and varied carbohydrate intake, a diet high in GL plays a role in the development of breast cancer.

Phaseolus beans: impact on glycaemic response and chronic disease risk in human subjects

Consumption of Phaseolus vulgaris bean species such as pinto, black, navy or kidney may be beneficial in the prevention and treatment of chronic diseases. In particular, conditions that are promoted by increased glycaemic stress (hyperglycaemia and hyperinsulinaemia) including diabetes, CVD and cancer seem to be reduced in individuals who eat more of these beans. The present paper discusses the influence of P. vulgaris species on glycaemic response and the impact that relationship may have on the risk of developing diabetes, CVD and cancer.

Dietary glycemic load, glycemic index, and carbohydrates on the risk of primary liver cancer among Chinese women and men

BACKGROUND

Dietary glycemic index (GI) and glycemic load (GL) typically have a positive relationship with obesity and diabetes, which are risk factors for liver cancer. However, studies on their association with liver cancer have yielded inconsistent results. Therefore, we assessed the association of GI, GL, and carbohydrates with liver cancer risk.

PATIENTS AND METHODS

A total of 72 966 women and 60 207 men from the Shanghai Women's Health Study (SWHS) and the Shanghai Men's Health Study (SMHS) were included for analysis. Food frequency questionnaire (FFQ) data were used to calculate daily dietary GI, GL, and carbohydrate intake. These values were energy adjusted and categorized into quintiles. The hazard ratios (HRs) and 95% confidence intervals (CI) were calculated with adjustment for potential confounders.

RESULTS

After a median follow-up time of 11.2 years for the SWHS and 5.3 years for the SMHS, 139 and 208 incident liver cancer cases were identified in the SWHS and SMHS, respectively. In multivariable Cox regression models, no statistically significant trends by quintile of GI, GL, or carbohydrate intake were observed. Stratification by chronic liver disease/hepatitis, diabetes, or body mass index (BMI) did not alter the findings.

CONCLUSIONS

There is little evidence that dietary GI, GL, or carbohydrates affect the incidence of liver cancer in this Asian population.

Dietary glycemic index and glycemic load and breast cancer risk in the European Prospective Investigation into Cancer and Nutrition (EPIC)

BACKGROUND

The glycemic potential of a diet is associated with chronically elevated insulin concentrations, which may augment breast cancer (BC) risk by stimulating insulin receptor or by affecting insulin-like growth factor I (IGF-I)-mediated mitogenesis. It is unclear whether this effect differs by BC phenotype.

OBJECTIVE

The objective was to investigate the relation between glycemic index (GI), glycemic load (GL), and total carbohydrate intake with BC by using data from the European Prospective Investigation into Cancer and Nutrition (EPIC).

DESIGN

We identified 11,576 women with invasive BC among 334,849 EPIC women aged 34-66 y (5th to 95th percentiles) at baseline over a median follow-up of 11.5 y. Dietary GI and GL were calculated from country-specific dietary questionnaires. We used multivariable Cox proportional hazards models to quantify the association between GI, GL, and carbohydrate intake and BC risk. BC tumors were classified by receptor status.

RESULTS

Overall GI, GL, and carbohydrates were not related to BC. Among postmenopausal women, GL and carbohydate intake were significantly associated with an increased risk of estrogen receptor-negative (ER(-)) BC when extreme quintiles (Q) were compared [multivariable HR(Q5-Q1) (95% CI) = 1.36 (1.02, 1.82; P-trend = 0.010) and HR(Q5-Q1) = 1.41 (1.05, 1.89; P-trend = 0.009), respectively]. Further stratification by progesterone receptor (PR) status showed slightly stronger associations with ER(-)/PR(-) BC [HR(Q5-Q1) (95% CI) = 1.48 (1.07, 2.05; P-trend = 0.010) for GL and HR(Q5-Q1) = 1.62 (1.15, 2.30; P-trend = 0.005) for carbohydrates]. No significant association with ER-positive BC was observed.

CONCLUSION

Our results indicate that a diet with a high GL and carbohydrate intake is positively associated with an increased risk of developing ER(-) and ER(-)/PR(-) BC among postmenopausal women.

Glycemic index, glycemic load and cancer risk

BACKGROUND

Dietary glycemic index (GI) and glycemic load (GL) have been related to the risk of selected cancers, but the issue remains open.

PATIENTS AND METHODS

Mailed questionnaires were completed between 1994 and 1997 in eight Canadian provinces for incident, histologically confirmed cases of the stomach (n=1182), colon (n=1727), rectum (n=1447), liver (n=309), pancreas (n=628), lung (n=3341), breast (n=2362), ovary (n=442), prostate (n=1799), testis (n=686), kidney (n=1345), bladder (n=1029), brain (n=1009), non-Hodgkin's lymphomas (NHL, n=1666), leukemias (n=1069), multiple myelomas (n=343), and 5039 population controls. Dietary information on eating habits 2 years before participants' enrollment in the study was obtained using a validated food frequency questionnaire (FFQ). Odds ratios (ORs) and 95% confidence intervals (CI) were derived by unconditional logistic regression including recognized confounding factors.

RESULTS

Dietary GI was positively associated with the risk of prostate cancer (OR, 1.26 for the highest versus the lowest quartile). A higher dietary GL significantly increased the risk of colorectal (OR, 1.28), rectal (OR, 1.44) and pancreatic (OR, 1.41) cancers. No other significant associations were found.

CONCLUSIONS

Our findings suggest that a diet high in GI and GL is associated with increased risk of selected cancers.

Evidence-based guideline of the German Nutrition Society: carbohydrate intake and prevention of nutrition-related diseases

The relative contribution of nutrition-related chronic diseases to the total disease burden of the society and the health care costs has risen continuously over the last decades. Thus, there is an urgent necessity to better exploit the potential of dietary prevention of diseases. Carbohydrates play a major role in human nutrition - next to fat, carbohydrates are the second biggest group of energy-yielding nutrients. Obesity, type 2 diabetes mellitus, dyslipoproteinaemia, hypertension, metabolic syndrome, coronary heart disease and cancer are wide-spread diseases, in which carbohydrates could have a pathophysiologic relevance. Correspondingly, modification of carbohydrate intake could have a preventive potential. In the present evidence-based guideline of the German Nutrition Society, the potential role of carbohydrates in the primary prevention of the named diseases was judged systematically. The major findings were: a high carbohydrate intake at the expense of total fat and saturated fatty acids reduces the concentrations of total, LDL and HDL cholesterol. A high carbohydrate consumption at the expense of polyunsaturated fatty acids increases total and LDL cholesterol, but reduces HDL cholesterol. Regardless of the type of fat being replaced, a high carbohydrate intake promotes an increase in the triglyceride concentration. Furthermore, a high consumption of sugar-sweetened beverages increases the risk of obesity and type 2 diabetes mellitus, whereas a high dietary fibre intake, mainly from whole-grain products, reduces the risk of obesity, type 2 diabetes mellitus, dyslipoproteinaemia, cardiovascular disease and colorectal cancer at varying evidence levels. The practical consequences for current dietary recommendations are presented.

Relationship between plasma glucose levels and malignant uterine cervical neoplasias

Background:

There is a direct correlation between glycemic load and the risk of developing many malignant neoplasms.

Aims:

The aim of this study was to determine the plasma glucose levels in women with cervical cancer.

Methods:

The study included 177 women with anatomopathologically diagnosed uterine cervical cancer (stages 0–IV) treated between 1980 and 2008 at the Gynecology and Obstetrics outpatient service of the UFTM, Brazil. The plasma glucose levels of all patients were assayed at the time of diagnosis and correlated with tumor staging.

Results:

We statistically compared the plasma glucose levels of group 1 (cervical intraepithelial neoplasia 2–3), group 2 (stage I–II), group 3 (stage III–IV), and group 4 (control group: leiomyomas). Patient groups with poor prognosis (groups 2 and 3) showed significantly higher plasma glucose levels (P < 0.05) than those with less aggressive lesions (group 1). Plasma glucose levels were significantly higher in groups 2 and 3 than in group 4 (P < 0.05). The comparison of number of patients with plasma glucose level >90 mg/dl showed CIN versus I/II: P = 0.0753; OR = 2.018; (95% CI: 0.9236 to 4.410) and CIN versus III/IV: P = 0.0975; OR = 2.400; (95% CI: 0.8335 to 6.911).

Conclusion:

We observed an association between high plasma glucose levels and cervical cancer cases with poor prognoses. Plasma glucose tests should be routinely used as additional prognostic parameters in patients with cervical neoplasias.

The glycemic index: physiological significance

The glycemic index (GI) is a physiological assessment of a food's carbohydrate content through its effect on postprandial blood glucose concentrations. Evidence from trials and observational studies suggests that this physiological classification may have relevance to those chronic Western diseases associated with overconsumption and inactivity leading to central obesity and insulin resistance. The glycemic index classification of foods has been used as a tool to assess potential prevention and treatment strategies for diseases where glycemic control is of importance, such as diabetes. Low GI diets have also been reported to improve the serum lipid profile, reduce C-reactive protein (CRP) concentrations, and aid in weight control. In cross-sectional studies, low GI or glycemic load diets (mean GI multiplied by total carbohydrate) have been associated with higher levels of high-density lipoprotein cholesterol (HDL-C), with reduced CRP concentrations, and, in cohort studies, with decreased risk of developing diabetes and cardiovascular disease. In addition, some case-control and cohort studies have found positive associations between dietary GI and risk of various cancers, including those of the colon, breast, and prostate. Although inconsistencies in the current findings still need to be resolved, sufficient positive evidence, especially with respect to renewed interest in postprandial events, suggests that the glycemic index may have a role to play in the treatment and prevention of chronic diseases.

Role of metformin in the management of polycystic ovary syndrome

Polycystic ovary syndrome is the most common endocrinological disorder affecting 4-12% of women and also the most controversial. Metformin was logically introduced to establish the extent to which hyperinsulinaemia influences the pathogenesis of the condition. Early studies were very encouraging. Randomized controlled studies and several metaanalyses have changed the picture and put the drug that was once heralded as magic in a much contracted place. More work is needed to establish its right place in particular with regards to the prevention of many gestational and long-term complications.

Glycemic load, glycemic index and breast cancer risk in a prospective cohort of Swedish women

High-glycemic load diets have been hypothesized to increase the risk of breast cancer but epidemiologic studies have yielded inconsistent findings. We examined the associations of carbohydrate intake, glycemic index and glycemic load with risk of overall and hormone receptor-defined breast cancer in the Swedish Mammography Cohort, a population-based cohort of 61,433 women who completed a food frequency questionnaire at enrollment in 1987-1990. During a mean follow-up of 17.4 years, we ascertained 2,952 incident cases of invasive breast cancer. Glycemic load but not carbohydrate intake or glycemic index was weakly positively associated with overall breast cancer risk (p for trend = 0.05). In analyses stratified by estrogen receptor (ER) and progesterone receptor (PR) status of the breast tumors, we observed statistically significant positive associations of carbohydrate intake, glycemic index and glycemic load with risk of ER+/PR- breast cancer; the multivariate relative risks comparing extreme quintiles were 1.34 [95% confidence interval (CI) = 0.93-1.94; p for trend = 0.04] for carbohydrate intake, 1.44 (95% CI = 1.06-1.97; p for trend = 0.01) for glycemic index and 1.81 (95% CI = 1.29-2.53; p for trend = 0.0008) for glycemic load. No associations were observed for ER+/PR+ or ER-/PR- breast tumors. These findings suggest that a high carbohydrate intake and diets with high glycemic index and glycemic load may increase the risk of developing ER+/PR- breast cancer.

Consumption of sweet foods and breast cancer risk: a case-control study of women on Long Island, New York

Several epidemiologic studies have reported a positive association between breast cancer risk and high intake of sweets, which may be due to an insulin-related mechanism. We investigated this association in a population-based case-control study of 1,434 cases and 1,440 controls from Long Island, NY. Shortly after diagnosis, subjects were interviewed in-person to assess potential breast cancer risk factors, and self-completed a modified Block food frequency questionnaire, which included 11 items pertaining to consumption of sweets (sweet beverages, added sugars, and various desserts) in the previous year. Using unconditional logistic regression models, we estimated the association between consumption of sweets and breast cancer. Consumption of a food grouping that included dessert foods, sweet beverages, and added sugars was positively associated with breast cancer risk [adjusted odds ratio (OR) comparing the highest to the lowest quartile: 1.27, 95% confidence interval (CI): 1.00-1.61]. The OR was slightly higher when only dessert foods were considered (OR: 1.55, 95% CI: 1.23-1.96). The association with desserts was stronger among pre-menopausal women (OR: 2.00, 95% CI: 1.32-3.04) than post-menopausal women (OR: 1.40, 95% CI: 1.07-1.83), although the interaction with menopause was not statistically significant. Our study indicates that frequent consumption of sweets, particularly desserts, may be associated with an increased risk of breast cancer. These results are consistent with other studies that implicate insulin-related factors in breast carcinogenesis.