Possible Benefit of Nuts in Type 2 Diabetes
Nuts; including peanuts; are now recognized as having the potential to improve the blood lipid profile and; in cohort studies; nut consumption has been associated with a reduced risk of coronary heart disease (CHD). More recently; interest has grown in the potential value of including nuts in the diets of individuals with diabetes. Data from the Nurses Health Study indicates that frequent nut consumption is associated with a reduced risk of developing diabetes and cardiovascular disease. Randomized controlled trials of patients with type 2 diabetes have confirmed the beneficial effects of nuts on blood lipids also seen in nondiabetic subjects; but the trials have not reported improvement in A1c or other glycated proteins. Acute feeding studies; however; have demonstrated the ability of nuts; when eaten with carbohydrate (bread); to depress postprandial glycemia. Furthermore; there was evidence of reduced postprandial oxidative stress associated with nut consumption. In terms of dietary composition; nuts have a good nutritional profile; are high in monounsaturated fatty acids (MUFA) and PUFA; and are good sources of vegetable protein. Incorporation of nuts in the diet may therefore improve the overall nutritional quality of the diet. We conclude that there is justification to consider the inclusion of nuts in the diets of individuals with diabetes in view of their potential to reduce CHD risk; even though their ability to influence overall glycemic control remains to be established.
The effect of nuts on inflammation
Inflammation is one of the recognised mechanisms involved in the development of atherosclerotic plaque and insulin resistance. Inflammatory or endothelial markers such as C-Reactive Protein (CRP); Interleukin-6 (IL-6); fibrinogen; Vascular Cell Adhesion Molecule-1 (VCAM-1) and Intracellular Adhesion Molecule-1 (ICAM-1) have been identified as independent predictors of cardiovascular disease (CVD) or diabetes in human prospective studies. Epidemiological and clinical studies suggest that some dietary factors; such as nÂ3 polyunsaturated fatty acids; antioxidant vitamins; dietary fiber; L-arginine and magnesium may play an important role in modulating inflammation. The relationship observed between frequent nut consumption and the reduced risk of cardiovascular mortality and type 2 diabetes in some prospective studies could be explained by the fact that nuts are rich in all of these modulator nutrients. In fact; frequent nut consumption has been associated with lower concentrations of some peripheral inflammation markers in cross-sectional studies. Nut consumption has also been shown to decrease the plasma concentration of CRP; IL-6 and some endothelial markers in recent clinical trials.
Legume and soy food intake and the incidence of type 2 diabetes in the Shanghai Women's Health Study.
BACKGROUND: It has been postulated that a diet high in legumes may be beneficial for the prevention of type 2 diabetes mellitus (type 2 DM). However; data linking type 2 DM risk and legume intake are limited. OBJECTIVE: The objective of the study was to examine the association between legume and soy food consumption and self-reported type 2 DM. DESIGN: The study was conducted in a population-based prospective cohort of middle-aged Chinese women. We followed 64;227 women with no history of type 2 DM; cancer; or cardiovascular disease at study recruitment for an average of 4.6 y. Participants completed in-person interviews that collected information on diabetes risk factors; including dietary intake and physical activity in adulthood. Anthropometric measurements were taken. Dietary intake was assessed with a validated food-frequency questionnaire at the baseline survey and at the first follow-up survey administered 2-3 y after study recruitment. RESULTS: We observed an inverse association between quintiles of total legume intake and 3 mutually exclusive legume groups (peanuts; soybeans; and other legumes) and type 2 DM incidence. The multivariate-adjusted relative risk of type 2 DM for the upper quintile compared with the lower quintile was 0.62 (95% CI: 0.51; 0.74) for total legumes and 0.53 (95% CI: 0.45; 0.62) for soybeans. The association between soy products (other than soy milk) and soy protein consumption (protein derived from soy beans and their products) with type 2 DM was not significant. CONCLUSIONS: Consumption of legumes; soybeans in particular; was inversely associated with the risk type 2 DM.
Including walnuts in a low fat/modified fat diet improves hdl cholesterol-to-total cholesterol ratios in patients with type 2 diabetes
OBJECTIVE: The aim of this study was to examine the effect of a moderate-fat diet inclusive of walnuts on blood lipid profiles in patients with type 2 diabetes. RESEARCH DESIGN AND METHODS: This was a parallel randomized controlled trial comparing three dietary advice groups each with 30% energy as fat: low fat; modified low fat; and modified low fat inclusive of 30 g of walnuts per day. Fifty-eight men and women; mean age 59.3 +/- 8.1 years; started the trial. Dietary advice was given at baseline with monthly follow-up and fortnightly phone calls for support. Body weight; percent body fat; blood lipids; HbA1c; total antioxidant capacity; and erythrocyte fatty acid levels were measured at 0; 3; and 6 months. Data were assessed by repeated-measures ANOVA with an intention-to-treat model. RESULTS: The walnut group achieved a significantly greater increase in HDL cholesterol-to-total cholesterol ratio (P=0.049) and HDL (P=0.046) than the two other treatment groups. A 10% reduction in LDL cholesterol was also achieved in the walnut group; reflecting a significant effect by group (P=0.032) and time (P=0.036). There were no significant differences between groups for changes in body weight; percent body fat; total antioxidant capacity; or HbA1c levels. The higher dietary polyunsaturated fat-to-saturated fat ratio and intakes of omega-3 fatty acids in the walnut group were confirmed by erythrocyte biomarkers of dietary intake. CONCLUSIONS: Structured "whole of diet" advice that included 30 g of walnuts/day delivering substantial amounts of polyunsaturated fatty acid improved the lipid profile of patients with type 2 diabetes.
Nuts; body weight and insulin resistance.
Traditionally; nuts have been considered a staple food; but because of their high energy and fat content are not considered good for body weight control or insulin sensitivity. Frequent consumption of nuts reduces the risk of coronary artery disease and type-2 diabetes and nut-enriched diets favourably alter blood lipids in normal and hypercholesterolemic individuals under controlled and free-living dietary conditions. However; whether or not frequent consumption of nuts can cause weight gain and impair insulin sensitivity is not fully understood. Review of the available data to date suggests that adding nuts to habitual diets of free-living individuals does not cause weight gain. In fact; nuts have a tendency to lower body weight and fat mass. In the context of calorie-restricted diets; adding nuts produces a more lasting and greater magnitude of weight loss among obese subjects while improving insulin sensitivity. Further studies are needed to clarify the effect of long-term (>/= year) consumption of nuts on body weight and their role in altering insulin sensitivity both in normal and type-2 diabetics. In the meantime; there is sufficient evidence to promote the inclusion of nuts as part of healthy diets.
Dietary cis-monounsaturated fatty acids and metabolic control in type 2 diabetes.
Whether low-fat; high-carbohydrate (CHO) diets or moderately high-fat; high-monounsaturated fatty acid (MUFA) diets are preferable for the treatment and prevention of diabetes has been a matter of debate. High-fat diets based on MUFA-rich oils or whole foods have been compared with high-CHO diets for effects on several cardiovascular risk outcomes in diabetic subjects. Early studies using metabolic diets with wide differences in total fat content (15-25% of energy) generally found a beneficial effect of MUFA diets on glycemic control and serum lipids. Recent studies using prescribed diets with a difference of
Omega-3 polyunsaturated fatty acid intake and islet autoimmunity in children at increased risk for type 1 diabetes.
CONTEXT: Cod liver oil supplements in infancy have been associated with a decreased risk of type 1 diabetes mellitus in a retrospective study. OBJECTIVE: To examine whether intakes of omega-3 and omega-6 fatty acids are associated with the development of islet autoimmunity (IA) in children. DESIGN; SETTING; AND PARTICIPANTS: A longitudinal; observational study; the Diabetes Autoimmunity Study in the Young (DAISY); conducted in Denver; Colorado; between January 1994 and November 2006; of 1770 children at increased risk for type 1 diabetes; defined as either possession of a high diabetes risk HLA genotype or having a sibling or parent with type 1 diabetes. The mean age at follow-up was 6.2 years. Islet autoimmunity was assessed in association with reported dietary intake of polyunsaturated fatty acids starting at age 1 year. A case-cohort study (N = 244) was also conducted in which risk of IA by polyunsaturated fatty acid content of erythrocyte membranes (as a percentage of total lipids) was examined. MAIN OUTCOME MEASURE: Risk of IA; defined as being positive for insulin; glutamic acid decarboxylase; or insulinoma-associated antigen-2 autoantibodies on 2 consecutive visits and still autoantibody positive or having diabetes at last follow-up visit. RESULTS: Fifty-eight children developed IA. Adjusting for HLA genotype; family history of type 1 diabetes; caloric intake; and omega-6 fatty acid intake; omega-3 fatty acid intake was inversely associated with risk of IA (hazard ratio [HR]; 0.45; 95% confidence interval [CI]; 0.21-0.96; P = .04). The association was strengthened when the definition of the outcome was limited to those positive for 2 or more autoantibodies (HR; 0.23; 95% CI; 0.09-0.58; P = .002). In the case-cohort study; omega-3 fatty acid content of erythrocyte membranes was also inversely associated with IA risk (HR; 0.63; 95% CI; 0.41-0.96; P = .03). CONCLUSION: Dietary intake of omega-3 fatty acids is associated with reduced risk of IA in children at increased genetic risk for type 1 diabetes.
Long-term adoption of a Mediterranean diet is associated with a better health status in elderly people; a cross-sectional survey in Cyprus
BACKGROUND: There is increasing evidence that there are protective health effects from diets which are high in fruits; vegetables; legumes; and whole grains; and which include fish; nuts; and low-fat dairy products. We sought to investigate the association of Mediterranean diet on clinical status of 150 elderly men and women. METHODS: During 2004 - 2005; we studied 53 men and 97 women; aged 65 to 100 years; from various areas of Cyprus. A diet score that assesses the inherent characteristics of the Mediterranean diet was developed for each individual (range 0-55). Adoption of the Mediterranean diet was evaluated against the presence of cardiovascular risk factors like hypertension; diabetes; hypercholesterolemia and obesity. RESULTS: 26% of men and 18% of women had diabetes; 60% of men and 58% of women had hypertension; 60% of men and 68% of women had hypercholesterolemia; and 34% of men and 52% of women were obese. More than 90% of the participants reported consistency in their dietary habits for at least the past 3-4 decades. A significant inverse correlation was observed between diet score and the number of the investigated risk factors (rho= -0.26; p< 0.001). When we took into account age; sex; smoking habits; and physical activity status; we observed that a 10-unit increase in the diet score was associated with 21% lower odds of having one additional risk factor in women (p< 0.001) and with 14% lower odds in men (p = 0.05). CONCLUSION: Adherence to a Mediterranean diet is associated with reduced odds of having hypercholesterolemia; hypertension; diabetes and obesity among elderly people.
Diets high and low in glycemic index versus high monounsaturated fat diets: effects on glucose and lipid metabolism in NIDDM.
OBJECTIVE: To examine the relative effects of high and low glycemic index (GI) carbohydrates; and monounsaturated fats on blood glucose and lipid metabolism in NIDDM subjects. SUBJECTS: Fourteen male and seven female variably controlled NIDDM subjects recruited by advertisement. SETTING: Free living outpatients. RESEARCH DESIGN: A repeated measures; within-subject design was used such that each subject consumed three diets: (a) a high-GI diet (53% CHO -21% fat; 63 GI units (glucose= 100)); (b) a low-GI diet (51% CHO -23% fat; 43 GI units); and (c) a high-mono high-GI diet (42% CHO -35% fat; 59 GI units) in random order and cross-over fashion for four weeks. Approximately 45% energy was provided as key foods which differed in published GI values and specifically excluded legumes. Dietary fibre intake was > 30 g/d on each diet. At the end of each dietary intervention; we measured fasting plasma lipids; glucose; insulin; total glycated plasma protein; fructosamine; LDL and HDL particle size as well as 24 h urinary excretion of glucose and C-peptide. RESULTS: HDL-cholesterol was higher on the low-GI and high-mono high-GI diets compared to the high-GI diet (P < 0.05 for overall diet effect). There were no other significant differences in metabolic control between diets; even when adjusted for BMI; glucose control or gender. Body weight and saturated fat intake remained stable between dietary interventions. CONCLUSION: High-mono high-GI and high-CHO; low-GI diets are superior to high-CHO; high-GI diets with respect to HDL metabolism but no effect was noted on glucose metabolism in variably controlled NIDDM subjects.