In recent years, there is growing evidence that plant-foods polyphenols, due to their biological properties, may be unique nutraceuticals and supplementary treatments for various aspects of type 2 diabetes mellitus. In this article we have reviewed the potential efficacies of polyphenols, including phenolic acids, flavonoids, stilbenes, lignans and polymeric lignans, on metabolic disorders and complications induced by diabetes. Based on several in vitro, animal models and some human studies, dietary plant polyphenols and polyphenol-rich products modulate carbohydrate and lipid metabolism, attenuate hyperglycemia, dyslipidemia and insulin resistance, improve adipose tissue metabolism, and alleviate oxidative stress and stress-sensitive signaling pathways and inflammatory processes. Polyphenolic compounds can also prevent the development of long-term diabetes complications including cardiovascular disease, neuropathy, nephropathy and retinopathy. Further investigations as human clinical studies are needed to obtain the optimum dose and duration of supplementation with polyphenolic compounds in diabetic patients.

Context:Overproduction of reactive oxygen and nitrogen species during physical exercise, exercise induced oxidative stress and antioxidant supplementation is interesting and controversial concepts that have been considered during the past decades.Evidence Acquisition:In this review, we aimed to summarize current evidence in relation to antioxidant supplementation outcomes during exercise and physical activity. For this aim, we obtained relevant articles through searches of the Medline and PubMed databases between 1980 to 2013. Although major studies have indicated that antioxidants could attenuate biomarkers of exercise-induced oxidative stress and the use of antioxidant supplement is a common phenomenon among athletes and physically active people, there are some doubts regarding the benefits of these.Results:It seems that the best recommendations regarding antioxidants and exercise are having a balanced diet rich in natural antioxidants and phytochemicals.Conclusions:Regular consumption of various fresh fruits and vegetables, whole grains, legumes and beans, sprouts and seeds is an effective and safe way to meet all antioxidant requirements in physically active persons and athletes.

Type 2 diabetes is a complicated metabolic disorder with both short- and long-term undesirable complications. In recent years, there has been growing evidence that functional foods and their bioactive compounds, due to their biological properties, may be used as complementary treatment for type 2 diabetes mellitus. In this review, we have highlighted various functional foods as missing part of medical nutrition therapy in diabetic patients. Several in vitro, animal models and some human studies, have demonstrated that functional foods and nutraceuticals may improve postprandial hyperglycemia and adipose tissue metabolism modulate carbohydrate and lipid metabolism. Functional foods may also improve dyslipidemia and insulin resistance, and attenuate oxidative stress and inflammatory processes and subsequently could prevent the development of long-term diabetes complications including cardiovascular disease, neuropathy, nephropathy and retinopathy. In conclusion available data indicate that a functional foods-based diet may be a novel and comprehensive dietary approach for management of type 2 diabetes.

Use of antioxidant components is a new approach for improvement of insulin resistance (IR) as a main feature of type 2 diabetes and its complications. The aim of this study was to investigate the effects of broccoli sprouts powder (BSP) containing high concentration of sulphoraphane on IR in type 2 diabetic patients. Eighty-one patients were randomly assigned to receive 10 g/d BSP (A, n = 27), 5 g/d BSP (B, n = 29) and placebo (C, n = 25) for 4 weeks. Fasting serum glucose and insulin concentration, glucose to insulin ratio and homoeostasis model assessment of IR (HOMA-IR) index were measured at baseline and again 4 weeks after treatment. Seventy-two patients completed the study and 63 were included in the analysis. After 4 weeks, consumption of 10 g/d BSP resulted in a significant decrease in serum insulin concentration and HOMA-IR (p = 0.05 for treatment effect). Therefore, broccoli sprouts may improve IR in type 2 diabetic patients.

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BackgroundThere is growing evidence that dietary antioxidants could have favorable effects on the attenuation and prevention of metabolic disorders. In the current study we investigated the association of dietary total antioxidant capacity (TAC) and metabolic syndrome (MetS) components and the occurrence of the MetS during a 3-year follow-up.MethodsThis longitudinal study was conducted in the framework of Tehran Lipid and Glucose Study, between 2006–2008 and 2009–2011, on 1983 adults, aged 19–70 y. The usual intakes of participant were measured using a validated semi-quantitative food frequency questionnaire and dietary TAC was estimated at baseline. The MetS components were assessed at baseline and 3 years later. Multiple logistic regression models were used to estimate the occurrence of the MetS and its components according to dietary TAC quartile categories.ResultsThe mean age of participants was 40.4 ± 13.0 y, and mean BMI was 27.03 ± 4.9 kg/m2 at baseline. After adjustment for potential confounding variables, TAC was associated with MetS components at baseline. Participant with highest TAC score had lower weight and abdominal fat gain during the 3 year follow-up. The chance of having the MetS, abdominal obesity and hypertension after 3 years decreased across the increasing dietary TAC quartile (P for trend < 0.01). Dietary TAC more than 1080 μmolTE/100 g of food, resulted in a 38% decrease in the risk of central obesity (OR = 0.62, 95% CI = 0.38-0.99).ConclusionWe demonstrated that higher dietary antioxidant intakes have favorable effects on metabolic disorders and, more interestingly, prevent subsequent weight and abdominal fat gain during a 3-year follow-up.

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The association of dietary phytochemical index and cardiometabolic risk factors in adults: Tehran Lipid and Glucose Study. J Hum Nutr Diet. 26 (Suppl. 1), 145-153 doi:10.1111/jhn.12048 Abstract Background: Phytochemicals are natural non-nutritive bioactive compounds found in fruits, vegetables, whole grains, nuts and legumes, as well as other plant foods. In the present study, we assessed the dietary phytochemical index (PI) in relation to cardiometabolic risk factors among Iranian adults. Methods: This cross-sectional study was conducted within the framework of third phase of Tehran Lipid and Glucose Study [2006][2007][2008]. For the present study, 2567 subjects aged 19-70 years (1129 men and 1438 women) were selected randomly. Dietary data were collected using a validated semi-quantitative food frequency questionnaire with 168 food items. The PI was calculated based on daily energy derived from phytochemical-rich foods. The odds ratios of abdominal obesity, impaired fasting glucose, hypertriglyceridaemia, low high-density lipoprotein-cholesterol and hypertension were assessed across PI quartile categories. Results: The mean (SD) age of participants was 39.4 (13.2) years. Participants in the upper quartile of PI were older, and had a lower weight and waist circumference. The mean (SD) of the PI was 17.3 (5.6), 25.5 (6.4), 32.7 (8.3) and 42.8 (10.5) in the first, second, third and fourth quartiles, respectively. Compared with those in the lower quartile of PI, participants in the upper quartiles had a 66% lower risk of abdominal obesity [95% confidence interval (CI) = 0.23-0.51] and a 36% lower risk of hypertriglyceridaemia (95% CI, 0.47-0.86), after adjustment for potential confounders. Conclusions: Higher intakes of phytochemical-rich foods are associated with a lower risk of abdominal obesity and hypertriglyceridaemia as the main cardiometabolic risk factors.