Fruit and vegetable intake and type 2 diabetes: EPIC-InterAct prospective study and meta-analysis

Dietary substitutions for refined carbohydrate that show promise for reducing risk of type 2 diabetes in men and women

Both genetics and lifestyle contribute to type 2 diabetes (T2D), a condition of elevated circulating glucose induced by a collection of metabolic defects including peripheral insulin resistance, elevated hepatic glucose output, and impaired pancreatic insulin secretion. Because the prevalence of T2D and its modifiable risk factors (overweight/obesity, dyslipidemia, hypertension, and physical inactivity) have been increasing in recent decades, there has been growing interest in lifestyle interventions that target T2D management and prevention. Although it is increasingly recognized that lifestyle interventions aimed at encouraging physical activity and reducing body weight can improve insulin sensitivity, nutritional contributions to T2D risk reduction are less clear. Evidence from prospective cohort and randomized controlled trials suggests that diets rich in refined dietary carbohydrate [particularly those with a high glycemic index (GI)] may elevate T2D risk; however, the appropriate combination of macronutrients to optimize metabolic health has not been fully described. To date, the collective evidence suggests that diets rich in low-GI carbohydrates, cereal fiber, resistant starch, fat from vegetable sources (unsaturated fat), and lean sources of protein should be emphasized, whereas refined sugars and grains (high-GI carbohydrates) are to be avoided in order to lower risk of T2D and its related risk factors and comorbidities.

Personalising nutritional guidance for more effective behaviour change

Improving diet and other lifestyle behaviours has considerable potential for reducing the global burden of non-communicable diseases, promoting better health across the life-course and increasing wellbeing. However, realising this potential will require the development, testing and implementation of much more effective behaviour change interventions than are used conventionally. Evidence-based, personalised (or stratified) interventions which incorporate effective behaviour change techniques (BCT) and which are delivered digitally are likely to be an important route to scalable and sustainable interventions. Progress in developing such interventions will depend on the outcomes of research on: (i) the best bases for personalisation of dietary advice; (ii) identification of BCT which are proven to enhance intervention efficacy; (iii) suitable platforms (digital-based tools) for collection of relevant participant characteristics (e.g. socioeconomic information, current diet and lifestyle and dietary preferences) linked with intelligent systems which use those characteristics to offer tailored feedback and advice in a cost-effective and acceptable manner. Future research should focus on such interventions aiming to reduce health inequalities and to improve overall public health.

Diet, lifestyle, and genetic risk factors for type 2 diabetes: a review from the Nurses' Health Study, Nurses' Health Study 2, and Health Professionals' Follow-up Study

The epidemiological evidence collected from three large US cohorts (Nurses' Health Study, Nurses' Health Study 2, and Health Professionals' Follow-up Study) has yielded important information regarding the roles of overall diet, individual foods and nutrients, physical activity and other lifestyle factors in the development of type 2 diabetes. Excess adiposity is a major risk factor for diabetes, and thus, maintaining a healthy body weight and avoidance of weight gain during adulthood is the cornerstone of diabetes prevention. Independent of body weight, the quality or type of dietary fat and carbohydrate is more crucial than the quantity in determining diabetes risk. Higher consumption of coffee, whole grains, fruits, and nuts is associated with lower risk of diabetes, whereas regular consumption of refined grains, red and processed meats, and sugar-sweetened beverages including fruits juices is associated with increased risk. Dietary patterns rich in fruits and vegetables, whole grains, and nuts and legumes but lower in red and processed meats, refined grains, and sugar-sweetened beverages are consistently associated with diabetes risk, even after adjustment for body mass index. The genome-wide association studies conducted in these cohorts have contributed substantially to the discoveries of novel genetic loci for type 2 diabetes and other metabolic traits, although the identified common variants explain only a small proportion of overall diabetes predisposition. Taken together, these ongoing large cohort studies have provided convincing epidemiologic evidence that a healthy diet, together with regular physical activity, maintenance of a healthy weight, moderate alcohol consumption, and avoidance of sedentary behaviors and smoking would prevent the majority of type 2 diabetes cases.

Epidemiology of diabetes

The disease burden related to diabetes is high and rising in every country, fuelled by the global rise in the prevalence of obesity and unhealthy lifestyles. The latest estimates show a global prevalence of 382 million people with diabetes in 2013, expected to rise to 592 million by 2035. The aetiological classification of diabetes has now been widely accepted. Type 1 and type 2 diabetes are the two main types, with type 2 diabetes accounting for the majority (>85%) of total diabetes prevalence. Both forms of diabetes can lead to multisystem complications of microvascular endpoints, including retinopathy, nephropathy and neuropathy, and macrovascular endpoints including ischaemic heart disease, stroke and peripheral vascular disease. The premature morbidity, mortality, reduced life expectancy and financial and other costs of diabetes make it an important public health condition.

Fruit and vegetable intake and risk of type 2 diabetes mellitus: meta-analysis of prospective cohort studies

OBJECTIVE

To clarify and quantify the potential dose-response association between the intake of fruit and vegetables and risk of type 2 diabetes.

DESIGN

Meta-analysis and systematic review of prospective cohort studies.

DATA SOURCE

Studies published before February 2014 identified through electronic searches using PubMed and Embase.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Prospective cohort studies with relative risks and 95% CIs for type 2 diabetes according to the intake of fruit, vegetables, or fruit and vegetables.

RESULTS

A total of 10 articles including 13 comparisons with 24,013 cases of type 2 diabetes and 434,342 participants were included in the meta-analysis. Evidence of curve linear associations was seen between fruit and green leafy vegetables consumption and risk of type 2 diabetes (p=0.059 and p=0.036 for non-linearity, respectively). The summary relative risk of type 2 diabetes for an increase of 1 serving fruit consumed/day was 0.93 (95% CI 0.88 to 0.99) without heterogeneity among studies (p=0.477, I(2)=0%). For vegetables, the combined relative risk of type 2 diabetes for an increase of 1 serving consumed/day was 0.90 (95% CI 0.80 to 1.01) with moderate heterogeneity among studies (p=0.002, I(2)=66.5%). For green leafy vegetables, the summary relative risk of type 2 diabetes for an increase of 0.2 serving consumed/day was 0.87 (95% CI 0.81 to 0.93) without heterogeneity among studies (p=0.496, I(2)=0%). The combined estimates showed no significant benefits of increasing the consumption of fruit and vegetables combined.

CONCLUSIONS

Higher fruit or green leafy vegetables intake is associated with a significantly reduced risk of type 2 diabetes.

Association of behaviour change techniques with effectiveness of dietary interventions among adults of retirement age: a systematic review and meta-analysis of randomised controlled trials

BACKGROUND

There is a need for development of more effective interventions to achieve healthy eating, enhance healthy ageing, and to reduce the risk of age-related diseases. The aim of this study was to identify the behaviour change techniques (BCTs) used in complex dietary behaviour change interventions and to explore the association between BCTs utilised and intervention effectiveness.

METHODS

We undertook a secondary analysis of data from a previous systematic review with meta-analysis of the effectiveness of dietary interventions among people of retirement age. BCTs were identified using the reliable CALO-RE taxonomy in studies reporting fruit and vegetable (F and V) consumption as outcomes. The mean difference in F and V intake between active and control arms was compared between studies in which the BCTs were identified versus those not using the BCTs. Random-effects meta-regression models were used to assess the association of interventions BCTs with F and V intakes.

RESULTS

Twenty-eight of the 40 BCTs listed in the CALO-RE taxonomy were identified in the 22 papers reviewed. Studies using the techniques 'barrier identification/problem solving' (93 g, 95% confidence interval (CI) 48 to 137 greater F and V intake), 'plan social support/social change' (78 g, 95%CI 24 to 132 greater F and V intake), 'goal setting (outcome)' (55 g 95%CI 7 to 103 greater F and V intake), 'use of follow-up prompts' (66 g, 95%CI 10 to 123 greater F and V intake) and 'provide feedback on performance' (39 g, 95%CI -2 to 81 greater F and V intake) were associated with greater effects of interventions on F and V consumption compared with studies not using these BCTs. The number of BCTs per study ranged from 2 to 16 (median = 6). Meta-regression showed that one additional BCT led to 8.3 g (95%CI 0.006 to 16.6 g) increase in F and V intake.

CONCLUSIONS

Overall, this study has identified BCTs associated with effectiveness suggesting that these might be active ingredients of dietary interventions which will be effective in increasing F and V intake in older adults. For interventions targeting those in the peri-retirement age group, 'barrier identification/problem solving' and 'plan for social support/social change' may be particularly useful in increasing the effectiveness of dietary interventions.

Global assessment of select phytonutrient intakes by level of fruit and vegetable consumption

Despite dietary recommendations that have repeatedly underscored the importance of increasing consumption of fruits and vegetables, intakes worldwide are lower than recommended levels. Consequently, the diets of many individuals may be lacking in nutrients and phytonutrients typical of a diet rich in a variety of fruits and vegetables. In the present study, we estimated phytonutrient intakes by adults categorised by sex, level of fruit and vegetable consumption (< 5 v. ≥ 5 servings/d), and geographic diet cluster. Intakes of nine select phytonutrients were estimated from the 2002-4 World Health Survey fruit and vegetable servings intake data (n 198,637), the FAO supply utilisation accounts data, and phytonutrient concentration data obtained from the US Department of Agriculture databases and the published literature. Percentage contributions to each phytonutrient intake from fruit and vegetable sources were also estimated. Estimated intakes of phytonutrients from fruits and vegetables varied across the thirteen geographic diet clusters, reflecting regional differences in both numbers and proportions of fruit and vegetable servings consumed, and the specific types of fruits and vegetables available in the diet. The mean phytonutrient intakes by adults consuming ≥ 5 servings/d of fruits and vegetables were approximately 2- to 6-fold the mean phytonutrient intakes by adults with low fruit and vegetable consumption (< 5 servings/d). In some cases, phytonutrient intakes by adults consuming ≥ 5 servings/d of fruits and vegetables in one geographic diet cluster were lower than the intakes by adults reporting < 5 servings/d in another cluster. The findings from this assessment provide important information regarding the major dietary patterns of phytonutrient intakes across geographic diet clusters.

Inverse association between diabetes and altitude: a cross-sectional study in the adult population of the United States

OBJECTIVE

To determine whether geographical elevation is inversely associated with diabetes, while adjusting for multiple risk factors.

METHODS

This is a cross-sectional analysis of publicly available online data from the Behavioral Risk Factor Surveillance System, 2009. Final dataset included 285,196 US adult subjects. Odds ratios were obtained from multilevel mixed-effects logistic regression analysis.

RESULTS

Among US adults (≥20 years old), the odds ratio for diabetes was 1.00 between 0 and 499 m of altitude (reference), 0.95 (95% confidence interval, 0.90-1.01) between 500 and 1,499 m, and 0.88 (0.81-0.96) between 1,500 and 3,500 m, adjusting for age, sex, body mass index, ethnicity, self-reported fruit and vegetable consumption, self-reported physical activity, current smoking status, level of education, income, health status, employment status, and county-level information on migration rate, urbanization, and latitude. The inverse association between altitude and diabetes in the US was found among men [0.84 (0.76-0.94)], but not women [1.09 (0.97-1.22)].

CONCLUSIONS

Among US adults, living at high altitude (1,500-3,500 m) is associated with lower odds of having diabetes than living between 0 and 499 m, while adjusting for multiple risk factors. Our findings suggest that geographical elevation may be an important factor linked to diabetes.

Adherence to a Mediterranean diet and risk of diabetes: a systematic review and meta-analysis

OBJECTIVE

Adherence to a Mediterranean diet is associated with significant improvements in health status. However, to date no systematic review and meta-analysis has summarized the effects of Mediterranean diet adherence on the risk of type 2 diabetes mellitus.

DESIGN

Electronic searches for randomized controlled trials and cohort studies were performed in MEDLINE, SCOPUS, EMBASE and the Cochrane Trial Register until 2 April 2014. Pooled effects were calculated by an inverse-variance random-effect meta-analysis using the statistical software Review Manager 5.2 by the Cochrane Collaboration.

SETTING

Meta-analysis of randomized controlled trials and cohort studies.

SUBJECTS

ELIGIBILITY CRITERIA

19+years of age.

RESULTS

One randomized controlled trial and eight prospective cohort studies (122 810 subjects) published between 2007 and 2014 were included for meta-analysis. For highest v. lowest adherence to the Mediterranean diet score, the pooled risk ratio was 0.81 (95 % CI 0.73, 0.90, P<0.0001, I 2=55 %). Sensitivity analysis including only long-term studies confirmed the results of the primary analysis (pooled risk ratio=0.75; 95 % CI 0.68, 0.83, P<0.00001, I 2=0 %). The Egger regression test provided no evidence of substantial publication bias (P=0.254).

CONCLUSIONS

Greater adherence to a Mediterranean diet is associated with a significant reduction in the risk of diabetes (19 %; moderate quality evidence). These results seem to be clinically relevant for public health, in particular for encouraging a Mediterranean-like dietary pattern for primary prevention of type 2 diabetes mellitus.

Bioavailability of vitamin D2 from enriched mushrooms in prediabetic adults: a randomized controlled trial

BACKGROUND/OBJECTIVES

Based on the growing evidence of risk reduction from fresh fruit and vegetable consumption and an inverse relationship between serum 25-hydroxyvitamin D (25OHD) and the risk of type 2 diabetes (T2D), we determined the benefits of regularly consuming vitamin D-enriched mushrooms in a prediabetic cohort. Exposing edible mushrooms to ultraviolet B (UVB) light increases vitamin D2 (D2) and raises serum 25OHD2 in healthy young adults; however, their benefit to deficient prediabetics and glucose metabolism remains untested.

SUBJECTS/METHODS

Forty-three prediabetic, D-deficient adults (25OHD≤20 ng/ml), BMI>25 were randomized to four groups consuming daily entrées containing 100 g fresh sliced cooked mushrooms prepared by a chef for 16 weeks. Two groups were fed UVB-treated mushrooms initially containing: 600 IU D2 or 4000 IU D2; each one also received one capsule of placebo daily. Two control groups were fed untreated mushrooms and D3 dietary supplements at two label doses: 600 IU D3 and 4000 IU D3. D2 and D3 content were analyzed in mushrooms, before and after cooking and in over-the-counter supplements.

RESULTS

After 16 weeks, both D2-UVB-mushroom entrée doses, which were significantly lower after cooking, produced modest or no increases in 25OHD2 or total 25OHD relative to the positive control subjects who actually consumed about 1242 and 7320 IU per day of D3 (higher than stated on the label).

CONCLUSIONS

Unanticipated D2 cooking loss from fresh UVB mushrooms and probable low absorption and/or hydroxylation may explain the smaller increase in 25OHD2 in our prediabetic overweight/obese cohort compared with past findings in younger, healthy subjects. Moreover, no dose or vitamin D source was associated with modifying T2D risk factors.

Prevention and management of type 2 diabetes: dietary components and nutritional strategies

In the past couple of decades, evidence from prospective observational studies and clinical trials has converged to support the importance of individual nutrients, foods, and dietary patterns in the prevention and management of type 2 diabetes. The quality of dietary fats and carbohydrates consumed is more crucial than is the quantity of these macronutrients. Diets rich in wholegrains, fruits, vegetables, legumes, and nuts; moderate in alcohol consumption; and lower in refined grains, red or processed meats, and sugar-sweetened beverages have been shown to reduce the risk of diabetes and improve glycaemic control and blood lipids in patients with diabetes. With an emphasis on overall diet quality, several dietary patterns such as Mediterranean, low glycaemic index, moderately low carbohydrate, and vegetarian diets can be tailored to personal and cultural food preferences and appropriate calorie needs for weight control and diabetes prevention and management. Although much progress has been made in development and implementation of evidence-based nutrition recommendations in developed countries, concerted worldwide efforts and policies are warranted to alleviate regional disparities.

Food and physical activity behaviours of adults attending a prediabetes education class

OBJECTIVES

The primary objective of this study was to examine food and physical activity behaviours of adults with prediabetes.

METHODS

For this cross-sectional study, adults (aged >17 years) with prediabetes (n=1228) who attended a prediabetes education class were recruited. Participants self-administered an assessment of food and physical activity behaviours using the Food Behaviour Checklist and the Godin Leisure Time Exercise Questionnaire. Linear regression models were performed to identify significant relationships between food, physical activity, age, body mass index and food access variables.

RESULTS

Participants were 35.8% men with a mean age of 57.7 years (SD 11.6) and 64.2% women with a mean age of 55.2 years (13.9). Neither group was consuming adequate fruits and vegetables (17.1% for men and 29.2% for women eating 5 or more servings a day) or meeting physical activity guidelines of 150 minutes (29.5% for men and 26.2% for women). Approximately 29.0% of the entire sample "always" consumed milk or soy products. Men reported higher saturated fat intakes than women. For the entire sample, 83.4% rated their diet quality as needing improvement, and most consumed sweetened beverages (71.1% of men and 50.9% of women). Many participants (88.5%) used nutrition facts panels to choose foods. Food behaviour subscales and physical activity were significantly associated with each other and with age, body mass index and food access (p<0.05).

CONCLUSIONS

Overall, adults with prediabetes reported less than optimal food and physical activity behaviours. Evaluation of lifestyle behaviours using simple tools like the Food Behaviour Checklist and Godin Leisure Time Exercise Questionnaire can be helpful for program design, evaluation and delivery.

Applying the precautionary principle to nutrition and cancer

PRIMARY OBJECTIVE

Research has identified certain foods and dietary patterns that are associated with reduced cancer risk and improved survival after cancer diagnosis. This research has formed the basis for dietary guidance issued by cancer organizations. Unfortunately, gaps within nutrition research have made it difficult to make recommendations in some areas. This review specifies suggested dietary guidance in which evidence of a dietary influence on cancer risk is substantial, even if not conclusive. Evidence summaries within the review are based on the 2007 report of the World Cancer Research Fund/American Institute for Cancer Research. This review also describes advantages and disadvantages of following the suggested dietary guidance and includes putative mechanisms involved in cancer progression.

MAIN OUTCOMES AND RESULTS

Suggested dietary guidance where evidence is sufficiently compelling include (1) limiting or avoiding dairy products to reduce the risk of prostate cancer; (2) limiting or avoiding alcohol to reduce the risk of cancers of the mouth, pharynx, larynx, esophagus, colon, rectum, and breast; (3) avoiding red and processed meat to reduce the risk of cancers of the colon and rectum; (4) avoiding grilled, fried, and broiled meats to reduce the risk of cancers of the colon, rectum, breast, prostate, kidney, and pancreas; (5) consumption of soy products during adolescence to reduce the risk of breast cancer in adulthood and to reduce the risk of recurrence and mortality for women previously treated for breast cancer; and (6) emphasizing fruits and vegetables to reduce risk of several common forms of cancer.

CONCLUSION

By adopting the precautionary principle for nutrition research, this review aims to serve as a useful tool for practitioners and patients.

Association between home availability and vegetable consumption in youth: a review

Objective

To systematically review literature examining the association between vegetable home availability and vegetable intake in youth.

Design

Articles were identified through December 2012 using a search of PubMed, PsychINFO and OVID/Medline databases, using the following keywords in varying combinations: home, environment, availability, vegetable, intake, consumption, children. Quantitative studies examining home vegetable availability and vegetable intake in children and adolescents were included. Fifteen studies were included that met inclusion criteria.

Setting

Studies were conducted in the USA (n 8), Australia (n 1), Greece (n 1), Iceland (n 1), Denmark (n 1), the UK (n 1), the Netherlands (n 1) and a combination of nine European countries (n 1).

Subjects

Various populations of children and adolescents were examined.

Results

Seven of the studies (47 %) found a positive association between vegetable availability and intake, with the others reporting null findings. There were no clear patterns of association by study design, age of subjects included, comprehensiveness of measures, or inclusion of covariates in analyses. Child report of home availability was associated with child vegetable intake (n 6, all found a positive association), while parent report of home availability was only minimally associated (n 9, one found a positive association; P=0·001 from post hoc Fisher’s exact test comparing parent v. child report).

Conclusions

Parent perception of availability may be closer to truth, given the parental role in food shopping and preparation. Therefore, to impact child vegetable intake, absolute availability may not be as important as child perception of vegetables in the home. Child perception of availability may be altered by level of familiarity with vegetables.

Biochanin A and prunetin improve epithelial barrier function in intestinal CaCo-2 cells via downregulation of ERK, NF-κB, and tyrosine phosphorylation

The single-layered gut epithelium represents the primary line of defense against environmental stressors; thereby monolayer integrity and tightness are essentially required to maintain gut health and function. To date only a few plant-derived phytochemicals have been described as affecting intestinal barrier function. We investigated the impact of 28 secondary plant compounds on the barrier function of intestinal epithelial CaCo-2/TC-7 cells via transepithelial electrical resistance (TEER) measurements. Apart from genistein, the compounds that had the biggest effect in the TEER measurements were biochanin A and prunetin. These isoflavones improved barrier tightness by 36 and 60%, respectively, compared to the untreated control. Furthermore, both isoflavones significantly attenuated TNFα-dependent barrier disruption, thereby maintaining a high barrier resistance comparable to nonstressed cells. In docking analyses exploring the putative interaction with the tyrosine kinase EGFR, these novel modulators of barrier tightness showed very similar values compared to the known tyrosine kinase inhibitor genistein. Both biochanin A and prunetin were also identified as potent reducers of NF-κB and ERK activation, zonula occludens 1 tyrosine phosphorylation, and metalloproteinase-mediated shedding activity, which may account for the barrier-improving ability of these isoflavones.

Antioxidants in food: content, measurement, significance, action, cautions, caveats, and research needs

There are a multitude of antioxidants in foods, especially in foods of plant origin. Higher intake of antioxidant-rich foods is clearly associated with better health and functional longevity. The specific agents and mechanisms responsible are not yet clear, but there is convincing evidence that including more plant-based, antioxidant-rich foods, herbs, and beverages in the diet is effective in promoting health and lowering risk of various age-related diseases. The content of some individual antioxidants, such as vitamin C, in food can be measured, but it is not feasible to attempt to measure each antioxidant separately, and methods have been developed to assess the "total antioxidant content" of foods. One of the most widely used methods is the ferric reducing/antioxidant power (FRAP) assay, which is relatively simple, quick, sensitive, and inexpensive to perform. There are many published studies that have used the FRAP assay, and these have generated a very large database of total antioxidant content of foods that can help guide food choices for increased antioxidant intake. The FRAP assay has also been used to assess the bioavailability of antioxidants in foods and to investigate the effects of growing conditions, storage, processing, and cooking method on the total antioxidant content of food. The test can be employed as a quality control check device, and to detect adulteration of food. Furthermore, in a modified form (FRASC), the assay can measure ascorbic acid content almost simultaneously with the total antioxidant content of the sample. In this chapter, basic concepts of oxidation and the role of antioxidants, as well as the types and action of different antioxidants in foods will be reviewed briefly, and the underpinning concepts and evidence for health benefits of increased intake of dietary antioxidants will be discussed, with some focus on vitamin C, and also in the context of our evolutionary development. The basic concepts and limitations of measuring "total antioxidant content" of food will be presented. The FRAP assay and the modified version FRASC will be described, and the total antioxidant content (as the FRAP value) of a range of foods will be presented. Finally, issues of bioavailability and redox balance will be discussed in relation to the biological significance and molecular action of antioxidants in foods, some caution and caveats are presented about overcoming biological barriers to absorption of antioxidant phytochemicals, and research needs to further our understanding in the important area of food, antioxidants, and health will be highlighted.

Dietary nitrate reduces resting metabolic rate: a randomized, crossover study in humans

BACKGROUND

Nitrate, which is an inorganic anion abundant in vegetables, increases the efficiency of isolated human mitochondria. Such an effect might be reflected in changes in the resting metabolic rate (RMR) and formation of reactive oxygen species. The bioactivation of nitrate involves its active accumulation in saliva followed by a sequential reduction to nitrite, nitric oxide, and other reactive nitrogen species.

OBJECTIVE

We studied effects of inorganic nitrate, in amounts that represented a diet rich in vegetables, on the RMR in healthy volunteers.

DESIGN

In a randomized, double-blind, crossover study, we measured the RMR by using indirect calorimetry in 13 healthy volunteers after a 3-d dietary intervention with sodium nitrate (NaNO₃) or a placebo (NaCl). The nitrate dose (0.1 mmol · kg⁻¹ · d⁻¹) corresponded to the amount in 200-300 g spinach, beetroot, lettuce, or other vegetable that was rich in nitrate. Effects of direct nitrite exposure on cell respiration were studied in cultured human primary myotubes.

RESULTS

The RMR was 4.2% lower after nitrate compared with placebo administration, and the change correlated strongly to the degree of nitrate accumulation in saliva (r² = 0.71). The thyroid hormone status, insulin sensitivity, glucose uptake, plasma concentration of isoprostanes, and total antioxidant capacity were unaffected by nitrate. The administration of nitrite to human primary myotubes acutely inhibited respiration.

CONCLUSIONS

Dietary inorganic nitrate reduces the RMR. This effect may have implications for the regulation of metabolic function in health and disease.

Nutrigenetics: bridging two worlds to understand type 2 diabetes

The increasing global prevalence of type 2 diabetes mellitus (T2DM) is a major public health concern. Accumulating data provides strong evidence of the shared contribution of genetic and environmental factors to T2DM risk. Genome-wide association studies have hugely improved our understanding of the genetic basis of T2DM. However, it is obvious that genetics only partly account for an individuals' predisposition to T2DM. The dietary environment has changed remarkably over the last century. Examination of individual macronutrients and more recently of foods and dietary patterns is becoming increasingly important in terms of developing public health strategies. Nutrigenetics offers the potential to improve diet-related disease prevention and therapy, but is not without its own challenges. In this review we present evidence on the dietary environment and genetics as risk factors for T2DM and bridging the 2 disciplines we highlight some key gene-nutrient interactions.

Behavioral contributions to the pathogenesis of type 2 diabetes

Behavioral contributions to the pathogenesis of prediabetes and Type 2 diabetes (T2D) include lifestyle behaviors including dietary intake, exercise, sedentariness, sleep, and stress. The purpose of this paper is to review evidence for the metabolic pathways by which the behavior is linked to T2D. Evidence for interventions, which change each of the lifestyle behaviors, is discussed. The article will close with a brief discussion on how new technologies may provide opportunities to better understand relationships between moment-to-moment fluctuations in behaviors and diabetes pathogenesis, as well as provide opportunities to personalize and adapt interventions to achieve successful behavior change and maintenance of that change. Especially promising are new technologies, which assist in tracking lifestyle behaviors along with clinical and metabolic outcomes.

Development and phytochemical characterization of high polyphenol red lettuce with anti-diabetic properties

Polyphenol-rich Rutgers Scarlet Lettuce (RSL) (Lactuca sativa L.) was developed through somaclonal variation and selection in tissue culture. RSL may contain among the highest reported contents of polyphenols and antioxidants in the category of common fruits and vegetables (95.6 mg/g dry weight and 8.7 mg/g fresh weight gallic acid equivalents and 2721 µmol/g dry weight and 223 µmol/g fresh weight Trolox equivalents). Three main compounds accumulate at particularly high levels in RSL: chlorogenic acid, up to 27.6 mg/g dry weight, cyanidin malonyl-glucoside, up to 20.5 mg/g dry weight, and quercetin malonyl-glucoside, up to 35.7 mg/g dry weight. Major polyphenolic constituents of RSL have been associated with health promotion as well as anti-diabetic and/or anti-inflammatory activities. Daily oral administration of RSL (100 or 300 mg/kg) for up to eight days acutely reduced hyperglycemia and improved insulin sensitivity in high fat diet-induced obese hyperglycemic mice compared to vehicle (water) control. Data presented here support possible use of RSL as a functional food for the dietary management of diabetes.

Dietary intakes of individual flavanols and flavonols are inversely associated with incident type 2 diabetes in European populations

Dietary flavanols and flavonols, flavonoid subclasses, have been recently associated with a lower risk of type 2 diabetes (T2D) in Europe. Even within the same subclass, flavonoids may differ considerably in bioavailability and bioactivity. We aimed to examine the association between individual flavanol and flavonol intakes and risk of developing T2D across European countries. The European Prospective Investigation into Cancer and Nutrition (EPIC)-InterAct case-cohort study was conducted in 8 European countries across 26 study centers with 340,234 participants contributing 3.99 million person-years of follow-up, among whom 12,403 incident T2D cases were ascertained and a center-stratified subcohort of 16,154 individuals was defined. We estimated flavonoid intake at baseline from validated dietary questionnaires using a database developed from Phenol-Explorer and USDA databases. We used country-specific Prentice-weighted Cox regression models and random-effects meta-analysis methods to estimate HRs. Among the flavanol subclass, we observed significant inverse trends between intakes of all individual flavan-3-ol monomers and risk of T2D in multivariable models (all P-trend < 0.05). We also observed significant trends for the intakes of proanthocyanidin dimers (HR for the highest vs. the lowest quintile: 0.81; 95% CI: 0.71, 0.92; P-trend = 0.003) and trimers (HR: 0.91; 95% CI: 0.80, 1.04; P-trend = 0.07) but not for proanthocyanidins with a greater polymerization degree. Among the flavonol subclass, myricetin (HR: 0.77; 95% CI: 0.64, 0.93; P-trend = 0.001) was associated with a lower incidence of T2D. This large and heterogeneous European study showed inverse associations between all individual flavan-3-ol monomers, proanthocyanidins with a low polymerization degree, and the flavonol myricetin and incident T2D. These results suggest that individual flavonoids have different roles in the etiology of T2D.

Association of fruits and vegetables consumption and related-vitamins with inflammatory and oxidative stress markers in prediabetic individuals

BACKGROUND

Dietary guidelines of 5 servings per day of fruits and vegetables (FV) offer a reasonable amount of vitamins to control organic processes, which may contribute to a favorable cardiometabolic profile. This study aimed at investigating whether the intake of the FV group as well as pro-vitamin A carotenoids and vitamins C and E were associated with circulating markers of oxidative stress, inflammation and insulin resistance in Brazilians individuals at cardiometabolic risk.

METHODS

This cross-sectional study included 205 individuals screened for diabetes prevention program in a healthcare center from the School of Public Health, University of São Paulo, conducted in 2008. Possible associations of consumption of FV group, as well as pro-vitamin A carotenoids and vitamins C and E, with circulating markers of oxidative stress (superoxide dismutase - SOD and oxidized LDL - oxLDL), inflammation (C reactive protein, TNF-α and adiponectin) and insulin resistance (HOMA-IR) were investigated. Pearson correlation coefficient, ANOVA and multiple linear regression were employed.

RESULTS

The sample (64.7% women) had a mean age of 54.1 ± 12.7 years and body mass index of 30.7 ± 5.7 kg/m2. Dietary, physical activity, anthropometric and laboratory data were obtained. Participants consumed a mean of 3.8 servings/day of FV; their FV intake was categorized into three groups: <2.5, 2.5-5.0 and >5.0 servings/day. Significant trends for lower waist circumference (103.4 ± 13.6 vs. 100.1 ± 12.2 vs. 98.2 ± 12.7 cm, p-trend <0.05) and higher adiponectin concentrations (10.4 ± 1.8 vs. 11.9 ± 1.9 vs. 13.6 ± 2.1 ng/mL, p-trend <0.05) were detected across categories. Associations between SOD concentrations (β 0.172 [0.110-0.688]) with FV consumption and between oxLDL concentrations with vitamins C (β -0.333 [-2.568 - -0.218]) and E (β -0.354 [-1.131- -0.110]) intakes, adjusted for age, gender, BMI, saturated fat intake, smoking and physical activity were found. Similar results were observed for the associations between oxLDL and FV intake, but significance disappeared adding adjustment for saturated fat, smoking and physical activity.

CONCLUSION

Our data suggest that the intake of FV or selected vitamins may be useful for identifying the oxidative stress and inflammation involved in the genesis of cardiometabolic diseases and for motivating at-risk patients for changing dietary habits.

Taiwanese vegetarians and omnivores: dietary composition, prevalence of diabetes and IFG

Introduction

Vegetarian diets have been shown to improve glucose metabolism and reduce risk for diabetes in Westerners but whether Chinese vegetarian diets have the same benefits is unknown.

Methods

We evaluated the association between diet and diabetes/impaired fasting glucose (IFG) among 4384 Taiwanese Buddhist volunteers and identified diabetes/IFG cases from a comprehensive review of medical history and fasting plasma glucose.

Results

Vegetarians had higher intakes of carbohydrates, fiber, calcium, magnesium, total and non-heme iron, folate, vitamin A, and lower intakes of saturated fat, cholesterol, and vitamin B12. Besides avoiding meat and fish, vegetarians had higher intakes of soy products, vegetables, whole grains, but similar intakes of dairy and fruits, compared with omnivores. The crude prevalence of diabetes in vegetarians versus omnivores is 0.6% versus 2.3% in pre-menopausal women, 2.8% versus 10% in menopausal women, and 4.3% versus 8.1% in men. Polytomous logistic regression adjusting for age, body mass index, family history of diabetes, education, leisure time physical activity, smoking and alcohol, showed that this vegetarian diet was negatively associated with diabetes and IFG in men (OR for diabetes: 0.49, 95% CI: 0.28–0.89; OR for IFG: 0.66, 95% CI: 0.46–0.95); in pre-menopausal women (OR for diabetes: 0.26, 95% CI: 0.06–1.21; OR for IFG: 0.60, 95% CI: 0.35–1.04); and in menopausal women (OR for diabetes: 0.25, 95% CI: 0.15–0.42; OR for IFG: 0.73, 95% CI: 0.56–0.95).

Conclusion

We found a strong protective association between Taiwanese vegetarian diet and diabetes/IFG, after controlling for various potential confounders and risk factors.

Diabetes in Europe: an update

Diabetes is among the leading causes of death in the IDF Europe Region (EUR), continues to increase in prevalence with diabetic macro- and microvascular complications resulting in increased disability and enormous healthcare costs. In 2013, the number of people with diabetes is estimated to be 56 million in EUR with an overall estimated prevalence of 8.5%. However, estimates of diabetes prevalence in 2013 vary widely in the 56 diverse countries in EUR from 2.4% in Moldova to 14.9% in Turkey. Trends in diabetes prevalence also vary between countries with stable prevalence since 2002 for many countries but a doubling of diabetes prevalence in Turkey. For 2035, a further increase of nearly 10 million people with diabetes is projected for the EUR. Prevalence of type 1 has also increased over the past 20 years in EUR and there was estimated to be 129,350 cases in children aged 0-14 years in 2013. Registries provide valid information on incidence of type 1 diabetes with more complete data available for children than for adults. There are large differences in distribution of risk factors for diabetes at the population level in EUR. Modifiable risk factors such as obesity, physical inactivity, smoking behaviour (including secondhand smoking), environmental pollutants, psychosocial factors and socioeconomic deprivation could be tackled to reduce the incidence of type 2 diabetes in Europe. In addition, diabetes management is a major challenge to health services in the European countries. Improved networking practices of health professionals and other stakeholders in combination with empowerment of people with diabetes and continuous quality monitoring need to be further developed in Europe.

Adherence to predefined dietary patterns and incident type 2 diabetes in European populations: EPIC-InterAct Study

AIMS/HYPOTHESIS

Few studies have investigated the relationship between predefined dietary patterns and type 2 diabetes incidence; little is known about the generalisability of these associations. We aimed to assess the association between predefined dietary patterns and type 2 diabetes risk in European populations.

METHODS

From among a case-cohort of 12,403 incident diabetes cases and 16,154 subcohort members nested within the prospective European Prospective Investigation into Cancer and Nutrition study, we used data on 9,682 cases and 12,595 subcohort participants from seven countries. Habitual dietary intake was assessed at baseline with country-specific dietary questionnaires. Two diet-quality scores (alternative Healthy Eating Index [aHEI], Dietary Approaches to Stop Hypertension [DASH] score) and three reduced rank regression (RRR)-derived dietary-pattern scores were constructed. Country-specific HRs were calculated and combined using a random-effects meta-analysis.

RESULTS

After multivariable adjustment, including body size, the aHEI and DASH scores were not significantly associated with diabetes, although for the aHEI there was a tendency towards an inverse association in countries with higher mean age. We observed inverse associations of the three RRR-derived dietary-pattern scores with diabetes: HRs (95% CIs) for a 1-SD difference were 0.91 (0.86, 0.96), 0.92 (0.84, 1.01) and 0.87 (0.82, 0.92). Random-effects meta-analyses revealed heterogeneity between countries that was explainable by differences in the age of participants or the distribution of dietary intake.

CONCLUSIONS/INTERPRETATION

Adherence to specific RRR-derived dietary patterns, commonly characterised by high intake of fruits or vegetables and low intake of processed meat, sugar-sweetened beverages and refined grains, may lower type 2 diabetes risk.

The EPIC-InterAct Study: A Study of the Interplay between Genetic and Lifestyle Behavioral Factors on the Risk of Type 2 Diabetes in European Populations

The rising prevalence of type 2 diabetes around the world and the global pattern of variation in risk between countries have been widely attributed to an interplay between rising rates of obesity and poor lifestyles, and genetic or developmental susceptibility to disease. Although this general hypothesis has been in existence for more than 50 years, the precise mechanisms that may explain it have remained uncertain. Advances in technology and the application of new methods in large scale population studies have made it possible to study these mechanisms. The InterAct project, funded by the European Commission, is a large case-cohort study which has verified 12,403 incident cases of type 2 diabetes, facilitating the study of genetic and lifestyle factors on the risk of type 2 diabetes among European populations.

Realistic changes in monounsaturated fatty acids and soluble fibers are able to improve glucose metabolism

BACKGROUND/OBJECTIVES

Cardioprotective effects of Mediterranean-style diet have been shown. Instead of excluding foods, replacement or addition may facilitate compliance with impact on glucose metabolism of individuals at cardiometabolic risk. This study investigated the effect of changing selected nutrients intake on glucose metabolism during a lifestyle intervention tailored to living conditions of prediabetic Brazilians.

SUBJECTS/METHODS

183 prediabetic adults treated under the Brazilian public health system underwent an 18-month intervention on diet and physical activity. Dietary counseling focused on reducing saturated fat replaced by unsaturated fatty acids. Data were collected at baseline and after follow-up. ANOVA and multiple linear regression were used to test association of changes in nutrients intake with changes in plasma glucose.

RESULTS

Changes in fasting and 2-h plasma glucose but not in weight, HOMA-IR or C-reactive protein decreased after intervention across tertiles of MUFA changes (p-trend 0.017 and 0.024, respectively). Regression models showed that increase in MUFA intake was independently associated with reduction in fasting (β -1.475, p = 0.008) and 2-h plasma glucose (β -3.321, p = 0.007). Moreover, increase in soluble fibers intake was associated with decrease in fasting plasma glucose (β -1.579, p = 0.038). Adjustment for anthropometric measurements did not change the results but did after including change in insulin in the models.

CONCLUSIONS

Increases of MUFA and soluble fibers intakes promote benefits on glucose metabolism, independently of adiposity, during a realistic lifestyle intervention in at-risk individuals. Mechanisms mediating these processes may include mainly insulin sensitivity improvement.

Dose-response effect of fruit and vegetables on insulin resistance in people at high risk of cardiovascular disease: a randomized controlled trial

OBJECTIVE

The purpose of this randomized controlled trial was to investigate the dose-response effect of fruit and vegetable (F&V) intake on insulin resistance (IR) in people who are overweight and at high risk of cardiovascular disease (CVD).

RESEARCH DESIGN AND METHODS

A total of 105 participants (mean age 56 years) followed a 4-week washout diet (one to two portions of F&Vs per day). Ninety-two participants completed the washout and were randomized to receive one to two, four, or seven portions of F&Vs per day for 12 weeks. IR was assessed at the start and end of this 12-week period by the two-step euglycemic-hyperinsulinemic clamp. Compliance was monitored using a combination of 4-day food diaries and plasma biomarkers of F&V intake.

RESULTS

A total of 89 participants completed the study. Participants attained self-reported F&V intakes of 1.8, 3.8, and 7.0 portions per day (P < 0.001) per group. There was a significant linear increase in serum lutein status across the groups, indicating good compliance (P < 0.001), and body weight was maintained (P = 0.77). No significant difference was found between groups in terms of a change in measures of whole-body, peripheral, or hepatic IR or adiponectin multimers.

CONCLUSIONS

Increased consumption of F&Vs, as advocated in public-health advice, has no effect on IR in overweight individuals who are at high risk of CVD when body weight is maintained. Recent evidence from systematic reviews indicates that particular classes or types of F&Vs may have particular antidiabetic properties; hence, it is possible that benefits may only be observed in response to a more specific fruit or vegetable intervention.

The association between dietary flavonoid and lignan intakes and incident type 2 diabetes in European populations: the EPIC-InterAct study

OBJECTIVE

To study the association between dietary flavonoid and lignan intakes, and the risk of development of type 2 diabetes among European populations.

RESEARCH DESIGN AND METHODS

The European Prospective Investigation into Cancer and Nutrition-InterAct case-cohort study included 12,403 incident type 2 diabetes cases and a stratified subcohort of 16,154 participants from among 340,234 participants with 3.99 million person-years of follow-up in eight European countries. At baseline, country-specific validated dietary questionnaires were used. A flavonoid and lignan food composition database was developed from the Phenol-Explorer, the U.K. Food Standards Agency, and the U.S. Department of Agriculture databases. Hazard ratios (HRs) from country-specific Prentice-weighted Cox regression models were pooled using random-effects meta-analysis.

RESULTS

In multivariable models, a trend for an inverse association between total flavonoid intake and type 2 diabetes was observed (HR for the highest vs. the lowest quintile, 0.90 [95% CI 0.77-1.04]; P value trend = 0.040), but not with lignans (HR 0.88 [95% CI 0.72-1.07]; P value trend = 0.119). Among flavonoid subclasses, flavonols (HR 0.81 [95% CI 0.69-0.95]; P value trend = 0.020) and flavanols (HR 0.82 [95% CI 0.68-0.99]; P value trend = 0.012), including flavan-3-ol monomers (HR 0.73 [95% CI 0.57-0.93]; P value trend = 0.029), were associated with a significantly reduced hazard of diabetes.

CONCLUSIONS

Prospective findings in this large European cohort demonstrate inverse associations between flavonoids, particularly flavanols and flavonols, and incident type 2 diabetes. This suggests a potential protective role of eating a diet rich in flavonoids, a dietary pattern based on plant-based foods, in the prevention of type 2 diabetes.

Taioba (Xanthosoma sagittifolium) leaves: nutrient composition and physiological effects on healthy rats

Several studies have shown that fruits and vegetables contribute to protect against degenerative pathologies such as cardiovascular diseases, diabetes, and cancer, mainly due to the presence of dietary fiber (DF) and polyphenols. Taioba (Xanthosoma sagittifolium) is an edible aroid widely grown in many parts of Africa, America, and Asia. The tubers portions of taioba are widely consumed; however, the leafy portions are generally discarded, despite their high nutritive value. In this study, we have partly characterized the DF of lyophiized taioba leaf (LTL), and assessed the possible protective effects on biochemical parameters and on bile acid (BA) production in colon and cecum, when fed to healthy rats for 4 wk. Forty-five Wistar rats were assigned to either of 5 groups: group 1 received AIN 93G diet (CG: Control); group 2 received AIN 93G containing 2.5% of cellulose + 2.5% inulin (CEIN_5%); group 3 received AIN 93G containing 2.5% of cellulose + 2.5% taioba fiber (CETA_5%); group 4 received AIN 93G containing 5% cellulose + 2.5% taioba fiber (CETA_7.5%); group 5 received AIN 93G containing 5% cellulose + 2.5% of inulin (CEIN_7.5%). LTL showed high contents of total fiber, predominantly comprising insoluble DF with glucose as the major monomer. Rats receiving LTL had increased fecal mass and fat excretion, and improved BA profiles by diminishing the proportion of secondary acids, thus suggesting that consumption of taioba leaf may have the property of lowering the risk of colon cancer.

Fruit and vegetable intake and risk of cardiovascular disease

A high intake of fruit and vegetables (FV) has been shown to be associated with reduced risk of a number of chronic diseases, including CVD. This review aims to provide an overview of the evidence that increased FV intake reduces risk of CVD, focusing on studies examining total FV intake. This evidence so far available is largely based on prospective cohort studies, with meta-analyses demonstrating an association between increased FV intake and reduced risk of both CHD and stroke. Controlled intervention trials examining either clinical or cardiovascular risk factor endpoints are scarce. However, such trials have shown that an increase in FV consumption can lower blood pressure and also improve microvascular function, both of which are commensurate with a reduced risk of CVD. The effects of increased FV consumption on plasma lipid levels, risk of diabetes and body weight have yet to be firmly established. In conclusion, evidence that FV consumption reduces the risk of CVD is so far largely confined to observational epidemiology, with further intervention studies required.

Fruit consumption and risk of type 2 diabetes: results from three prospective longitudinal cohort studies

OBJECTIVE

To determine whether individual fruits are differentially associated with risk of type 2 diabetes.

DESIGN

Prospective longitudinal cohort study.

SETTING

Health professionals in the United States.

PARTICIPANTS

66,105 women from the Nurses' Health Study (1984-2008), 85,104 women from the Nurses' Health Study II (1991-2009), and 36,173 men from the Health Professionals Follow-up Study (1986-2008) who were free of major chronic diseases at baseline in these studies.

MAIN OUTCOME MEASURE

Incident cases of type 2 diabetes, identified through self report and confirmed by supplementary questionnaires.

RESULTS

During 3,464,641 person years of follow-up, 12,198 participants developed type 2 diabetes. After adjustment for personal, lifestyle, and dietary risk factors of diabetes, the pooled hazard ratio of type 2 diabetes for every three servings/week of total whole fruit consumption was 0.98 (95% confidence interval 0.97 [corrected] to 0.99). With mutual adjustment of individual fruits, the pooled hazard ratios of type 2 diabetes for every three servings/week were 0.74 (0.66 to 0.83) for blueberries, 0.88 (0.83 to 0.93) for grapes and raisins, 0.89 (0.79 to 1.01) for prunes, 0.93 (0.90 to 0.96) for apples and pears, 0.95 (0.91 to 0.98) for bananas, 0.95 (0.91 to 0.99) for grapefruit, 0.97 (0.92 to 1.02) for peaches, plums, and apricots, 0.99 (0.95 to 1.03) for oranges, 1.03 (0.96 to 1.10) for strawberries, and 1.10 (1.02 to 1.18) for cantaloupe. The pooled hazard ratio for the same increment in fruit juice consumption was 1.08 (1.05 to 1.11). The associations with risk of type 2 diabetes differed significantly among individual fruits (P<0.001 in all cohorts).

CONCLUSION

Our findings suggest the presence of heterogeneity in the associations between individual fruit consumption and risk of type 2 diabetes. Greater consumption of specific whole fruits, particularly blueberries, grapes, and apples, is significantly associated with a lower risk of type 2 diabetes, whereas greater consumption of fruit juice is associated with a higher risk.

The oral microbiome and nitric oxide homoeostasis

The tiny radical nitric oxide (NO) participates in a vast number of physiological functions including vasodilation, nerve transmission, host defence and cellular energetics. Classically produced by a family of specific enzymes, NO synthases (NOSs), NO signals via reactions with other radicals or transition metals. An alternative pathway for the generation of NO is the nitrate-nitrite-NO pathway in which the inorganic anions nitrate (NO(3)(-)) and nitrite (NO(2)(-)) are reduced to NO and other reactive nitrogen intermediates. Nitrate and nitrite are oxidation products from NOS-dependent NO generation but also constituents in our diet, mainly in leafy green vegetables. Irrespective of origin, active uptake of circulating nitrate in the salivary glands, excretion in saliva and subsequent reduction to nitrite by oral commensal bacteria are all necessary steps for further NO generation. This central role of the oral cavity in regulating NO generation from nitrate presents a new and intriguing aspect of the human microbiome in health and disease. In this review, we present recent advances in our understanding of the nitrate-nitrite-NO pathway and specifically highlight the importance of the oral cavity as a hub for its function.

Fruits and vegetables: measuring intake and encouraging increased consumption

A high intake of fruit and vegetables (FV) is associated with reduced risk of chronic disease, although the evidence base is mostly observational. Blood biomarkers offer an objective indicator of FV intake, potentially improving estimates of intakes based on traditional methods. A valid biomarker of overall FV intake would be able to confirm population intakes, more precisely evaluate the association between intakes and health outcomes and confirm compliance in FV interventions. Several substances have been proposed as biomarkers of FV intake: vitamin C, the carotenoids and polyphenols. Certain biomarkers are strong predictors of single FV; however, the proposed single biomarkers of FV consumption are only modestly predictive of overall FV consumption. This is likely to be due to the complexity of the FV food group. While accurately measuring FV intake is important in nutrition research, another critical question is: how best can an increase in FV intake be achieved? Increased FV intake has been achieved in efficacy studies using intensive dietary advice. Alternative, less intensive methods for encouraging FV consumption need to be developed and tested for population level intervention. Systematic reviews suggest peer support to be an effective strategy to promote dietary change. This review will describe the evidence for a link between increased FV intake and good health, outline possible novel biomarkers of FV consumption, present the most recently available data on population intake of FV and examine the usefulness of different approaches to encourage increased consumption of FV.

The complex interplay of genetic and lifestyle risk factors in type 2 diabetes: an overview

Type 2 diabetes (T2D) is one of the scourges of modern times, with many millions of people affected by the disease. Diabetes occurs most frequently in those who are overweight or obese. However, not all overweight and obese persons develop diabetes, and there are those who develop the disease who are lean and physically active. Certain ethnicities, especially indigenous populations, are at considerably higher risk of obesity and diabetes than those of white European ancestry. The patterns and distributions of diabetes have led some to speculate that the disease is caused by interactions between genetic and obesogenic lifestyle factors. Whilst to many this is a plausible explanation, remarkably little reliable evidence exists to support it. In this review, an overview of published literature relating to genetic and lifestyle risk factors for T2D is provided. The review also describes the concepts and rationale that have motivated the view that gene-lifestyle interactions cause diabetes and overviews the empirical evidence published to date to support this hypothesis.