Carbohydrates and cancer: an overview of the epidemiological evidence

Introduction to Nutrition and Cancer

By the beginning of the year 2021, the estimated number of new cancer cases worldwide was about 19.3 million and there were 10.0 million cancer-related deaths. Cancer is one of the deadliest diseases worldwide that can be attributed to genetic and environmental factors, including nutrition. The good nutrition concept focuses on the dietary requirements to sustain life. There is a substantial amount of evidence suggesting that a healthy diet can modulate cancer risk, particularly the risk of colorectal and breast cancers. Many studies have evaluated the correlation between our diet and the risk of cancer development, prevention, and treatment. The effect of diet on cancer development is likely to happen through intertwining mechanisms including inflammation and immune responses. For instance, a greater intake of red and processed meat along with low consumption of fruits and vegetables has been associated with increased levels of inflammatory biomarkers that are implicated in cancer development. On the other hand, the consumption of phytosterols, vitamins, and minerals, which exert antioxidant and anti-inflammatory roles have been linked to lower cancer risk, or even its occurrence prevention. In this book, we aim to summarize the current knowledge on the role of nutrition in cancer to provide the best scientific advice in this regard.

An application of carbohydrate polymers-based surface-modified gold nanoparticles for improved target delivery to liver cancer therapy - A systemic review

Gold nanoparticles have been broadly investigated as cancer diagnostic and therapeutic agents. Gold nanoparticles are a favorable drug delivery vehicle with their unique subcellular size and good biocompatibility. Chitosan, agarose, fucoidan, porphyran, carrageenan, ulvan and alginate are all examples of biologically active macromolecules. Since they are biocompatible, biodegradable, and irritant-free, they find extensive application in biomedical and macromolecules. The versatility of these compounds is enhanced because they are amenable to modification by functional groups like sulfation, acetylation, and carboxylation. In an eco-friendly preparation process, the biocompatibility and targeting of GNPs can be improved by functionalizing them with polysaccharides. This article provides an update on using carbohydrate-based GNPs in liver cancer treatment, imaging, and drug administration. Selective surface modification of several carbohydrate types and further biological uses of GNPs are focused on.

The underexplored links between cancer and the internal body climate: Implications for cancer prevention and treatment

In order to effectively manage and cure cancer we should move beyond the general view of cancer as a random process of genetic alterations leading to uncontrolled cell proliferation or simply a predictable evolutionary process involving selection for traits that increase cell fitness. In our view, cancer is a systemic disease that involves multiple interactions not only among cells within tumors or between tumors and surrounding tissues but also with the entire organism and its internal "milieu". We define the internal body climate as an emergent property resulting from spatial and temporal interactions among internal components themselves and with the external environment. The body climate itself can either prevent, promote or support cancer initiation and progression (top-down effect; i.e., body climate-induced effects on cancer), as well as be perturbed by cancer (bottom-up effect; i.e., cancer-induced body climate changes) to further favor cancer progression and spread. This positive feedback loop can move the system towards a "cancerized" organism and ultimately results in its demise. In our view, cancer not only affects the entire system; it is a reflection of an imbalance of the entire system. This model provides an integrated framework to study all aspects of cancer as a systemic disease, and also highlights unexplored links that can be altered to both prevent body climate changes that favor cancer initiation, progression and dissemination as well as manipulate or restore the body internal climate to hinder the success of cancer inception, progression and metastasis or improve therapy outcomes. To do so, we need to (i) identify cancer-relevant factors that affect specific climate components, (ii) develop 'body climate biomarkers', (iii) define 'body climate scores', and (iv) develop strategies to prevent climate changes, stop or slow the changes, or even revert the changes (climate restoration).

Dietary glycemic index, glycemic load, and lung cancer risk: A case-control study in Los Angeles County

BACKGROUND

Although there is some evidence of positive associations between both the glycemic index (GI) and glycemic load (GL) with cancer risk, the relationships with lung cancer risk remain largely unexplored. We evaluated the associations between GI and GL with lung cancer.

METHODS

The analyses were performed using data from a population-based case-control study recruited between 1999 and 2004 in Los Angeles County. Dietary factors were collected from 593 incident lung cancer cases and 1026 controls using a modified food frequency questionnaire. GI and GL were estimated using a food composition table. Adjusted odds ratios (ORs) and 95 % confidence intervals (CI) were estimated using unconditional logistic regression adjusting for potential confounders.

RESULTS

Dietary GI was positively associated with lung cancer (OR for upper vs. lower tertile = 1.62; 95 % CI: 1.17, 2.25). For histologic subtypes, positive associations were observed between GI and adenocarcinoma (OR for upper vs. lower tertile = 1.82; 95 % CI: 1.22, 2.70) and small cell carcinoma (OR for upper vs. lower tertile = 2.68; 95 % CI: 1.25, 5.74). No clear association between GL and lung cancer was observed.

CONCLUSION

These findings suggest that high dietary GI was associated with increased lung cancer risk, and the positive associations were observed for both lung adenocarcinoma and small cell lung carcinoma. Replication in an independent dataset is merited for a broader interpretation of our results.

Free fatty acids receptors 2 and 3 control cell proliferation by regulating cellular glucose uptake

BACKGROUND

Colorectal cancer (CRC) is a worldwide problem, which has been associated with changes in diet and lifestyle pattern. As a result of colonic fermentation of dietary fibres, short chain free fatty acids are generated which activate free fatty acid receptors (FFAR) 2 and 3. FFAR2 and FFAR3 genes are abundantly expressed in colonic epithelium and play an important role in the metabolic homeostasis of colonic epithelial cells. Earlier studies point to the involvement of FFAR2 in colorectal carcinogenesis.

AIM

To understand the role of short chain FFARs in CRC.

METHODS

Transcriptome analysis console software was used to analyse microarray data from CRC patients and cell lines. We employed short-hairpin RNA mediated down regulation of FFAR2 and FFAR3 genes, which was validated using quantitative real time polymerase chain reaction. Assays for glucose uptake and cyclic adenosine monophosphate (cAMP) generation was done along with immunofluorescence studies to study the effects of FFAR2/FFAR3 knockdown. For measuring cell proliferation, we employed real time electrical impedance-based assay available from xCELLigence.

RESULTS

Microarray data analysis of CRC patient samples showed a significant down regulation of FFAR2 gene expression. This prompted us to study the FFAR2 in CRC. Since, FFAR3 shares significant structural and functional homology with FFAR2, we knocked down both these receptors in CRC cell line HCT 116. These modified cell lines exhibited higher proliferation rate and were found to have increased glucose uptake as well as increased level of glucose transporter 1. Since, FFAR2 and FFAR3 signal through G protein subunit (Gαi), knockdown of these receptors was associated with increased cAMP. Inhibition of protein kinase A (PKA) did not alter the growth and proliferation of these cells indicating a mechanism independent of cAMP/PKA pathway.

CONCLUSION

Our results suggest role of FFAR2/FFAR3 genes in increased proliferation of colon cancer cells via enhanced glucose uptake and exclude the role of PKA mediated cAMP signalling. Alternate pathways could be involved that would ultimately result in increased cell proliferation as a result of down regulated FFAR2/FFAR3 genes. This study paves the way to understand the mechanism of action of short chain FFARs in CRC.

The Role of Autophagy in Liver Epithelial Cells and Its Impact on Systemic Homeostasis

Autophagy plays a role in several physiological and pathological processes as it controls the turnover rate of cellular components and influences cellular homeostasis. The liver plays a central role in controlling organisms’ metabolism, regulating glucose storage, plasma proteins and bile synthesis and the removal of toxic substances. Liver functions are particularly sensitive to autophagy modulation. In this review we summarize studies investigating how autophagy influences the hepatic metabolism, focusing on fat accumulation and lipids turnover. We also describe how autophagy affects bile production and the scavenger function within the complex homeostasis of the liver. We underline the role of hepatic autophagy in counteracting the metabolic syndrome and the associated cardiovascular risk. Finally, we highlight recent reports demonstrating how the autophagy occurring within the liver may affect skeletal muscle homeostasis as well as different extrahepatic solid tumors, such as melanoma.

Fructose and prostate cancer: toward an integrated view of cancer cell metabolism

Activation of glucose transporter-1 (Glut-1) gene expression is a molecular feature of cancer cells that increases glucose uptake and metabolism. Increased glucose uptake is the basis for the clinical localization of primary tumors using positron emission tomography (PET) and 2-deoxy-2-[18F]-fluoro-D-glucose (FDG) as a radiotracer. However, previous studies have demonstrated that a considerable number of cancers, which include prostate cancer (CaP), express low to undetectable levels of Glut-1 and that FDG-PET has limited clinical applicability in CaP. This observation could be explained by a low metabolic activity of CaP cells that may be overcome using different hexoses, such as fructose, as the preferred energy source. However, these hypotheses have not been examined critically in CaP. This review article summarizes what is currently known about transport and metabolism of hexoses, and more specifically fructose, in CaP and provides experimental evidences indicating that CaP cells may have increased capacity to transport and metabolize fructose in vitro and in vivo. Moreover, this review highlights recent findings that allow better understanding of how metabolism of fructose may regulate cancer cell proliferation and how fructose uptake and metabolism, through the de novo lipogenesis pathway, may provide new opportunities for CaP early diagnosis, staging, and treatment.

Starch-enriched diet modulates the glucidic profile in the rat colonic mucosa

PURPOSE

The protective function of the intestinal mucosa largely depends on carbohydrate moieties that as a part of glycoproteins and glycolipids form the epithelial glycocalyx or are secreted as mucins. Modifications of their expression can be induced by an altered intestinal microenvironment and have been associated with inflammatory disorders and colorectal cancer. Given the influence of dietary factors on the gut ecosystem, here we have investigated whether a long term feeding on a starch-rich diet can modulate the glucidic profile in the colonic mucosa of rats.

METHODS

Animals were divided into two groups and maintained for 9 months at different diets: one group was fed a standard diet, the second was fed a starch-enriched diet. Samples of colonic mucosa, divided in proximal and distal portions, were processed for microscopic analysis. Conventional stainings and lectin histochemistry were applied to identify acidic glycoconjugates and specific sugar residues in oligosaccharide chains, respectively. Some lectins were applied on adjacent sections after sialidase/fucosidase digestion, deacetylation, and oxidation to characterize either terminal dimers or sialic acid acetylation.

RESULTS

An increase in sulfomucins was found to be associated with the starch-enriched diet that affected also the expression of several sugar residues as well as fucosylated and sialylated sequences in both proximal and distal colon.

CONCLUSIONS

Although the mechanisms leading to such a modulation are at present unknown, either an altered intestinal microbiota or a dysregulation of glycosylation patterns might be responsible for the types and distribution of changes in the glucidic profile here observed.

Mathematical aspects of nutrition systems projecting for dietary therapy

The mathematical toolkit created and used for the design of durable nutrition systems aimed at the prevention and therapy of the diseases caused by calcium deficiency is analyzed. In particular, these are: the complex of mathematical models of the expendable diets and methods of the ingredients content optimization in them, mathematical model of daily diets optimization, and formalizationed method of fast and light determination of a diet’s biological value.The ways for the improvement of the developed mathematical toolkit aimed at the creation of the nutrition systems with higher level of both nutrients balance and provision of daily needs in them on the basis of using unconventional floury products enriched with the deficient nutrients, functionals for balancing the connected groups of nutrients are determined, as well as the introduction of aggregated restrictions on these groups of nutrients to the models (both products and rations).

Carbohydrate intake, obesity, metabolic syndrome and cancer risk? A two-part systematic review and meta-analysis protocol to estimate attributability

INTRODUCTION

Linkages between carbohydrates, obesity and cancer continue to demonstrate conflicting results. Evidence suggests inconclusive direct linkages between carbohydrates and specific cancers. Conversely, obesity has been strongly linked to a wide range of cancers. The purpose of the study is to explore linkages between carbohydrate intake and cancer types using a two-step approach. First the study will evaluate the linkages between carbohydrate intake and obesity, potentially stratified by metabolic syndrome status. Second, the estimated attributable fraction of obesity ascribed to carbohydrate intake will be multiplied against obesity attributable fractions for cancer types to give estimated overall attributable fraction for carbohydrate versus cancer type.

METHODS AND ANALYSIS

We will perform a comprehensive search to identify all possible published and unpublished studies that have assessed risk factors for obesity including dietary carbohydrate intake. Scientific databases, namely PubMed MEDLINE, EMBASE, EBSCOhost and ISI Web of Science will be searched. Following study selection, paper/data acquisition, and data extraction and synthesis, we will appraise the quality of studies and risk of bias, as well as assess heterogeneity. Meta-weighted attributable fractions of obesity due to carbohydrate intake will be estimated after adjusting for other potential confounding factors (eg, physical inactivity, other dietary intake). Furthermore, previously published systematic reviews assessing the cancer-specific risk associated with obesity will also be drawn. These estimates will be linked with the attributability of carbohydrate intake in part 1 to estimate the cancer-specific burden that can be attributed to dietary carbohydrates. This systematic review protocol has been developed according to the 'Preferred Reporting Items for Systematic review and Meta-Analysis Protocols (PRISMA-P) 2015'.

ETHICS AND DISSEMINATION

The current study will be based on published literature and data, and, as such, ethics approval is not required. The final results of this two part systematic review (plus multiplicative calculations) will be published in a relevant international peer-reviewed journal.

TRIAL REGISTRATION NUMBER

PROSPERO CRD42015023257.

A case-control study of glycemic index, glycemic load and dietary fiber intake and risk of adenocarcinomas and squamous cell carcinomas of the esophagus: the Australian Cancer Study

Background

Glycemic index (GI) and glycemic load (GL) have been investigated as etiologic factors for some cancers, but epidemiological data on possible associations between dietary carbohydrate intake and esophageal cancer are scant. This study examined the association between GI, GL, and other dietary carbohydrate components and risk of adenocarcinomas and squamous cell carcinoma of the esophagus accounting for established risk factors.

Methods

We analyzed data from a population-based Australian case-control study (2002-05) comprising 299 adenocarcinoma (EAC), 337 gastro-esophageal junction adenocarcinoma (EGJAC), 245 squamous cell carcinoma (ESCC), and 1507 controls sampled from a population registry. Dietary information was obtained using a 135-item food frequency questionnaire (FFQ); GI and GL were derived from an Australian GI database. Multivariable logistic regression models were used to derive odds ratios (ORs).

Results

All three case groups tended to have a lower intake of fiber, and significantly higher intake of fat, total energy, and alcohol (ESCC only) compared to controls. GI was unrelated to all histological types. Higher GL was not associated with risk of EAC and EGJAC, but was inversely associated with risk of ESCC (adjusted model, p_trend = 0.006), specifically among men where we observed a 58% reduced risk of ESCC in the highest versus the lowest quartile. Increased intake of total carbohydrates and starch was related to similarly large risk reductions of ESCC. Fiber intake was strongly and inversely associated with risk of EAC, EGJAC and ESCC (all p_trend ≤0.001), indicating risk reductions of 28%-37% per 10 g/day.

Conclusions

This study suggests a reduced risk of esophageal SCC with higher GL level particularly in men, but provides no evidence for the role of GI in the development of esophageal cancer. In addition, increased fiber intake appears to be associated with lower risk of all histological types of esophageal cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2407-14-877) contains supplementary material, which is available to authorized users.

Dietary fiber and the glycemic index: a background paper for the Nordic Nutrition Recommendations 2012

The aim of this study is to review recent data on dietary fiber (DF) and the glycemic index (GI), with special focus on studies from the Nordic countries regarding cardiometabolic risk factors, type 2 diabetes, cardiovascular disease, cancer, and total mortality. In this study, recent guidelines and scientific background papers or updates on older reports on DF and GI published between 2000 and 2011 from the US, EU, WHO, and the World Cancer Research Fund were reviewed, as well as prospective cohort and intervention studies carried out in the Nordic countries. All of the reports support the role for fiber-rich foods and DF as an important part of a healthy diet. All of the five identified Nordic papers found protective associations between high intake of DF and health outcomes; lower risk of cardiovascular disease, type 2 diabetes, colorectal and breast cancer. None of the reports and few of the Nordic papers found clear evidence for the GI in prevention of risk factors or diseases in healthy populations, although association was found in sub-groups, e.g. overweight and obese individuals and suggestive for prevention of type 2 diabetes. It was concluded that DF is associated with decreased risk of different chronic diseases and metabolic conditions. There is not enough evidence that choosing foods with low GI will decrease the risk of chronic diseases in the population overall. However, there is suggestive evidence that ranking food based on their GI might be of use for overweight and obese individuals. Issues regarding methodology, validity and practicality of the GI remain to be clarified.

The hexosamine biosynthetic pathway and O-GlcNAcylation drive the expression of β-catenin and cell proliferation

The short half-life protooncogene β-catenin acquires a remarkable stability in a large subset of cancers, mainly from mutations affecting its proteasomal degradation. In this sense, colorectal cancers (CRC) form a group of pathologies in which early steps of development are characterized by an aberrant expression of β-catenin and an uncontrolled proliferation of epithelial cells. Diet has long been described as an influence in the emergence of CRC, but the molecular events that link metabolic disorders and CRC remain elusive. Part of the explanation may reside in hexosamine biosynthetic pathway (HBP) flux. We found that fasted mice being force-fed with glucose or glucosamine leads to an increase of β-catenin and O-GlcNAcylation levels in the colon. MCF7 cells possessing intact Wnt/β-catenin signaling heavily expressed β-catenin when cultured in high glucose; this was reversed by the HBP inhibitor azaserine. HBP inhibition also decreased the expression of β-catenin in HT29 and, to a lesser extent, HCT116 cells. The same observation was made with regard to the transcriptional activity of β-catenin in HEK293 cells. Inhibition of HBP also blocked the glucose-mediated proliferation capacity of MCF7 cells, demonstrating that glucose affects both β-catenin expression and cell proliferation through the HBP. The ultimate element conducting these events is the dynamic posttranslational modification O-GlcNAcylation, which is intimately linked to HBP; the modulation of its level affected the expression of β-catenin and cell proliferation. In accordance with our findings, we propose that metabolic disorders correlate to CRC via an upregulation of HBP that reverberates on high O-GlcNAcylation levels including modification of β-catenin.

Sugars in diet and risk of cancer in the NIH-AARP Diet and Health Study

Prospective epidemiologic data on the effects of different types of dietary sugars on cancer incidence have been limited. In this report, we investigated the association of total sugars, sucrose, fructose, added sugars, added sucrose and added fructose in the diet with risk of 24 malignancies. Participants (n = 435,674) aged 50-71 years from the NIH-AARP Diet and Health Study were followed for 7.2 years. The intake of individual sugars was assessed using a 124-item food frequency questionnaire (FFQ). Cox proportional hazards regression was used to estimate hazard ratios (HR) and 95% confidence intervals (CI) in multivariable models adjusted for confounding factors pertinent to individual cancers. We identified 29,099 cancer cases in men and 13,355 cases in women. In gender-combined analyses, added sugars were positively associated with risk of esophageal adenocarcinoma (HR(Q5 vs. Q1) : 1.62, 95% CI: 1.07-2.45; p(trend) = 0.01), added fructose was associated with risk of small intestine cancer (HR(Q5 vs. Q1) : 2.20, 95% CI: 1.16-4.16; p(trend) = 0.009) and all investigated sugars were associated with increased risk of pleural cancer. In women, all investigated sugars were inversely associated with ovarian cancer. We found no association between dietary sugars and risk of colorectal or any other major cancer. Measurement error in FFQ-reported dietary sugars may have limited our ability to obtain more conclusive findings. Statistically significant associations observed for the rare cancers are of interest and warrant further investigation.

Impact of perinatal prebiotic consumption on gestating mice and their offspring: a preliminary report

To assess the impact of prebiotic supplementation during gestation and fetal and early neonatal life, gestating BALB/cj dam mice were fed either a control or a prebiotic (galacto-oligosaccharides-inulin, 9:1 ratio)-enriched diet throughout pregnancy and lactation, and allowed to nurse their pups until weaning. At the time of weaning, male offspring mice were separated from their mothers, weaned to the same solid diet as their dam and their growth was monitored until killed 48 d after weaning. Prebiotic treatment affected neither the body-weight gain nor the food intake of pregnant mice. In contrast, at the time of weaning, pups that had been nursed by prebiotic-fed dams had a higher body weight (11.0 (se 1.2) g) than pups born from control dams (9.8 (se 0.9) g). At 48 d after weaning, significantly higher values were observed for colon length and muscle mass in the offspring of prebiotic-fed dams (1.2 (se 0.1) cm/cm and 5.7 (se 1.8) mg/g, respectively), compared with control offspring (1.1 (se 0.1) cm/cm and 2.9 (se 0.9) mg/g, respectively), without any difference in spleen and stomach weight, or serum leptin concentration. The present preliminary study suggests that altering the fibre content of the maternal diet during both pregnancy and lactation enhances offspring growth, through an effect on intestinal and muscle mass rather than fat mass accretion.

An oat bran meal influences blood insulin levels and related gene sets in peripheral blood mononuclear cells of healthy subjects

The understanding of how fibre-rich meals regulate molecular events at a gene level is limited. This pilot study aimed to investigate changes in gene expression in peripheral blood mononuclear cells (PBMCs) from healthy subjects after consumption of an oat bran-rich meal. Fifteen subjects (8 men and 7 women, aged 20-28 years) ingested meals with oat bran or a control meal after an overnight fast. Blood samples for analysis of postprandial glucose, insulin and triglyceride concentrations were taken during 3 h, while PBMCs for microarray gene expression profiling from five men and five women were taken before and 2 h after the meal. Analysis of transcriptome data was performed with linear mixed models to determine differentially expressed genes in response either to meal intake or meal content, and enrichment analysis was used to identify functional gene sets responding to meal intake and specifically to oat bran intake. Meal intake as such affected gene expression for genes mainly involved in metabolic stress; indicating increased inflammation due to the switch from fasting to fed state. The oat bran meal affected gene sets associated with a lower insulin level, compared with the control meal. The gene sets included genes involved in insulin secretion and β-cell development, but also protein synthesis and genes related to cancer diseases. The oat bran meal also significantly lowered postprandial blood insulin IAUC compared to control. Further studies are needed to compare these acute effects with the long-term health effects of oat bran.

Consumption of diets high in prebiotic fiber or protein during growth influences the response to a high fat and sucrose diet in adulthood in rats

Background

Early dietary exposure can influence susceptibility to obesity and type 2 diabetes later in life. We examined the lasting effects of a high protein or high prebiotic fiber weaning diet when followed by a high energy diet in adulthood.

Methods

At birth, litters of Wistar rats were culled to 10 pups. At 21 d pups were weaned onto control (C), high prebiotic fiber (HF) or high protein (HP) diet. Rats consumed the experimental diets until 14 wk when they were switched to a high fat/sucrose (HFHS) diet for 6 wk. Body composition and energy intake were measured and an oral glucose tolerance test (OGTT) performed. Blood was analyzed for satiety hormones and tissues collected for real-time PCR.

Results

Weight gain was attenuated in male rats fed HF from 12 wk until study completion. In females there were early reductions in body weight that moderated until the final two wk of HFHS diet wherein HF females weighed less than HP. Final body weight was significantly higher following the high fat challenge in male and female rats that consumed HP diet from weaning compared to HF. Lean mass was higher and fat mass lower with HF compared to HP and compared to C in males. Energy intake was highest in HP rats, particularly at the start of HFHS feeding. Plasma glucose was higher in HP rats compared to HF during an OGTT. Plasma amylin was higher in HF females compared to C and glucagon-like peptide-1 (GLP-1) was higher in HF rats during the OGTT. Leptin was higher in HP rats during the OGTT. HF upregulated GLUT 5 mRNA expression in the intestine and downregulated hepatic hydroxymethylglutaryl coenzyme A reductase. Male rats fed HP had higher hepatic triglyceride content than C or HF.

Conclusion

These data suggest that while a long-term diet high in protein predisposes to an obese phenotype when rats are given a high energy diet in adulthood, consumption of a high fiber diet during growth may provide some protection.

Impact of substituting added sugar in carbonated soft drinks by intense sweeteners in young adults in the Netherlands: example of a benefit-risk approach

PURPOSE

Substituting added sugar in carbonated soft drinks with intense sweeteners may have potential beneficial, but also adverse health effects. This study assessed the benefits and risks associated with substituting added sugar in carbonated soft drinks with intense sweeteners in young adults in the Netherlands.

METHODS

A tiered approach was used analogous to the risk assessment paradigm, consisting of benefit and hazard identification, exposure assessment and finally benefit and risk characterization and comparison. Two extreme scenarios were compared in which all carbonated soft drinks were sweetened with either intense sweeteners or added sugar. National food consumption survey data were used, and intake of added sugar and intense sweeteners was calculated using the food composition table or analytical data for sweetener content.

RESULTS

Reduction in dental caries and body weight were identified as benefits of substituting sugar. The mean difference in total energy intake between the scenarios was 542 kJ per day in men and 357 kJ per day in women, under the assumption that no compensation takes place. In the 100% sweetener scenario, the average BMI decreased 1.7 kg/m(2) in men and 1.3 kg/m(2) in women when compared to the 100% sugar scenario. Risks are negligible, as the intake of intense sweeteners remains below the ADI in the substitution scenario.

CONCLUSIONS

Substitution of added sugar by intense sweeteners in carbonated soft drinks has beneficial effects on BMI and the reduction in dental caries, and does not seem to have adverse health effects in young adults, given the available knowledge and assumptions made.

Evolution of the human diet: linking our ancestral diet to modern functional foods as a means of chronic disease prevention

The evolution of the human diet over the past 10,000 years from a Paleolithic diet to our current modern pattern of intake has resulted in profound changes in feeding behavior. Shifts have occurred from diets high in fruits, vegetables, lean meats, and seafood to processed foods high in sodium and hydrogenated fats and low in fiber. These dietary changes have adversely affected dietary parameters known to be related to health, resulting in an increase in obesity and chronic disease, including cardiovascular disease (CVD), diabetes, and cancer. Some intervention trials using Paleolithic dietary patterns have shown promising results with favorable changes in CVD and diabetes risk factors. However, such benefits may be offset by disadvantages of the Paleolithic diet, which is low in vitamin D and calcium and high in fish potentially containing environmental toxins. More advantageous would be promotion of foods and food ingredients from our ancestral era that have been shown to possess health benefits in the form of functional foods. Many studies have investigated the health benefits of various functional food ingredients, including omega-3 fatty acids, polyphenols, fiber, and plant sterols. These bioactive compounds may help to prevent and reduce incidence of chronic diseases, which in turn could lead to health cost savings ranging from $2 to $3 billion per year as estimated by case studies using omega-3 and plant sterols as examples. Thus, public health benefits should result from promotion of the positive components of Paleolithic diets as functional foods.

Diets enriched in oat bran or wheat bran temporally and differentially alter the composition of the fecal community of rats

A clear understanding of how diet alters gastrointestinal communities is important given the suggested link between gut community composition and a wide variety of disease pathologies. To characterize this link for commonly consumed dietary fiber sources, we investigated the change in the fecal community of rats fed diets containing 5% nonnutritive fiber (control), 3% (wt:wt) oat bran plus 2% nonnutritive fiber (OB), or 5% (w/w) wheat bran (WB) over a 28-d feeding trial using both molecular- and cultivation-based methodologies. Pooled fecal samples from 8 rats fed the same diet were analyzed at 4 time points. On d 28, bran-fed rats had approximately twice the total cultivable bacteria than rats fed the control diet. Over the course of feeding, the cultivable community was initially dominated by bacteroides, then by bifidobacteria, lactobacilli, enterococci, and various enterics. In contrast, molecular analysis revealed the appearance of new operational taxonomic units (phylotypes) that were both temporally and inequitably distributed throughout the fecal community. The majority of change occurred in 2 major lineages within the Firmicutes: the Clostridium coccoides group and the Clostridium leptum subgroup. The time course of change depended on the source of bran, with the majority of new phylotypes appearing by d 14 (OB) or d 28 (WB), although adaptation of the fecal community was slow and continued over the entire feeding trial. Bacterial community richness was higher in bran-fed rats than in those fed the control diet. Change within the C. coccoides and C. leptum lineages likely reflect their high abundance within the gut bacterial community and the role of clostridia in fiber digestion. The results illustrate the limitations of relying solely on cultivation to assess bacterial changes and illustrate that community changes are complex in an ecosystem containing high numbers of interdependent and competing species of bacteria.

Impact of diet on breast cancer risk

PURPOSE OF REVIEW

Breast cancer is the most common female cancer in Western Europe and North America, and becoming an increasing problem in developing countries such as India and China. We review recent studies (published 1 January 2007-31 August 2008) on the impact of diet on breast cancer risk.

RECENT FINDINGS

Recent studies have focused on the controversial association for dietary fat and breast cancer as well as the role of newer aspects such as glycemic index, dietary patterns and diet-gene interactions. Evidence that some of the associations may be modified by oestrogen and progesterone receptor status has been presented. Still, only alcohol intake, being overweight and weight gain have shown consistent and strong positive associations with breast cancer risk. The reasons for the null or weak associations often observed regarding diet and breast cancer might be several. For example, there may be no causal association, or existing associations may be masked by measurement error, timing of dietary exposure and differences according to tumour characteristics or diet-gene interactions.

SUMMARY

Numerous epidemiological studies on diet and breast cancer have been published during our review period. Still, only alcohol intake, being overweight and weight gain have shown consistent and strong positive associations with breast cancer risk.

On the role and fate of sugars in human nutrition and health. Introduction

The recently implemented European Regulation (EC) No. 1924/2006 on nutrition and health claims made on foods is fuelling scientific research efforts in the food and health arena. Essentially, it is now established that only claims that are scientifically substantiated will be allowed. Because this new legislation covers the idea that foods with health or nutritional claims might be perceived by consumers as having a health advantage over products without claims, it introduces a further requirement (enclosing the new concept of 'nutrient profile') to avoid a situation where claims could mislead consumers when trying to make healthy choices in the context of a balanced diet. Thus, only those foods having an appropriate nutrition profile (composition of different nutrients such as sugars and other substances with particularly relevant nutritional or physiological effects) will be allowed to bear claims. A scientific expert workshop was organized to critically review the available evidence behind current intake recommendations for sugars, focusing on the strength/gaps of the scientific evidence available and the identification of those fields where further research is needed. Work was distributed in the following topics covering potential effects of dietary sugars on (i) body weight control; (ii) diabetes-insulin resistance; (iii) dental health and (iv) micronutrient dilution. New approaches, including intervention studies and the application of nutrigenomic technologies, should be undertaken and interpreted bearing in mind that foods, food components and their combinations can have both positive and negative effects on health, thus requiring benefit-risk analysis.

Glycemic index, glycemic load, and risk of digestive tract neoplasms: a systematic review and meta-analysis

BACKGROUND

Habitual consumption of diets with a high glycemic index (GI) and a high glycemic load (GL) may influence cancer risk via hyperinsulinemia and the insulin-like growth factor axis.

OBJECTIVE

The objective was to conduct a systematic review to assess the association between GI, GL, and risk of digestive tract cancers.

DESIGN

Medline and Embase were searched for relevant publications from inception to July 2008. When possible, adjusted results from a comparison of cancer risk of the highest compared with the lowest category of GI and GL intake were combined by using random-effects meta-analyses.

RESULTS

Cohort and case-control studies that examined the risk between GI or GL intake and colorectal cancer (n = 12) and adenomas (n = 2), pancreatic cancer (n = 6), gastric cancer (n = 2), and squamous-cell esophageal carcinoma (n = 1) were retrieved. Most case-control studies observed positive associations between GI and GL intake and these cancers. However, pooled cohort study results showed no associations between colorectal cancer risk and GI intake [relative risk (RR): 1.04; 95% CI: 0.92, 1.12; n = 7 studies] or GL intake (RR: 1.06; 95% CI: 0.95, 1.17; n = 8 studies). Furthermore, no significant associations were observed in meta-analyses of cohort study results of colorectal cancer subsites and GI and GL intake. Similarly, no significant associations emerged between pancreatic cancer risk and GI intake (RR: 0.99; 95% CI: 0.83, 1.19; n = 5 studies) or GL intake (RR: 1.01; 95% CI: 0.86, 1.19; n = 6 studies) in combined cohort studies.

CONCLUSIONS

The findings from our meta-analyses indicate that GI and GL intakes are not associated with risk of colorectal or pancreatic cancers. There were insufficient data available regarding other digestive tract cancers to make any conclusions about GI or GL intake and risk.

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

This systematic review aimed to examine if an association exists between dietary glycaemic index (GI) and glycaemic load (GL) intake and breast cancer risk. A systematic search was conducted in Medline and Embase and identified 14 relevant studies up to May 2008. Adjusted relative risk estimates comparing breast cancer risk for the highest versus the lowest category of GI/GL intake were extracted from relevant studies and combined in meta-analyses using a random-effects model. Combined estimates from six cohort studies show non-significant increased breast cancer risks for premenopausal women (relative risk (RR) 1.14, 95% CI 0.95-1.38) and postmenopausal women (RR 1.11, 95% CI 0.99-1.25) consuming the highest versus the lowest category of GI intake. Evidence of heterogeneity hindered analyses of GL and premenopausal risk, although most studies did not observe any significant association. Pooled cohort study results indicated no association between postmenopausal risk and GL intake (RR 1.03, 95% CI 0.94-1.12). Our findings do not provide strong support of an association between dietary GI and GL and breast cancer risk.

Glycemic index, glycemic load, and cancer risk: a meta-analysis

BACKGROUND

Factors linked to glucose metabolism play an important role in the development of cancers, and both glycemic index (GI) and glycemic load (GL) have been investigated as potential etiologic factors.

OBJECTIVE

A meta-analysis was performed to explore the association between GI and GL and cancer risk from published studies.

DESIGN

A comprehensive, systematic bibliographic search of the medical literature was conducted to identify relevant studies. Case-control and cohort studies published before October 2007 that reported cancer risk estimates for GI and GL were included. Pooled relative risks (RRs) were estimated for breast, colorectal, endometrial, and pancreatic cancer.

RESULTS

Thirty-nine studies were included in the meta-analysis. The interquantile ranges of GL were significantly wider in case-control studies, most of which were conducted in European countries, than in cohort studies. Cohort studies that presented lower ranges of GL also reported lower risk estimates. Overall, both GL and GI were significantly associated with a greater risk of colorectal (summary RR = 1.26; 95% CI: 1.11, 1.44 and RR = 1.18; 95% CI: 1.05, 1.34, respectively) and endometrial (RR = 1.36; 95% CI: 1.14, 1.62 and RR = 1.22; 95% CI: 1.01, 1.49) cancer than of breast and pancreatic cancer. There was, however, a significant between-study heterogeneity for colorectal cancer (P < 0.0001). The association between GL and breast cancer disappeared when publication bias was taken into account. No association was found for pancreatic cancer.

CONCLUSION

This comprehensive meta-analysis of GI and GL and cancer risk suggested an overall direct association with colorectal and endometrial cancer.