Natoli, S., P. McCoy, 2007. A review of the evidence: nuts and body weight. Asia Pac J Clin Nutr. 16 (4):588-597 588.
There is currently no single dietary or lifestyle intervention that is effective in long-term weight loss. Traditional weight loss diets tend to be low in total fat and therefore often restrict nut consumption. However, nuts are an important source of many vitamins, minerals, monounsaturated and polyunsaturated fatty acids. This paper reviewed all the available evidence from the literature in relation to nut consumption and body weight. The findings show that the role of nut consumption in body weight management is varied. Nuts, when included as part of an energy-controlled diet, were found in some instances to assist with weight loss. However, when nuts were added to an existing diet without controlling for energy intake, body weight increased, although to a lesser extent than theoretically predicted. There is limited evidence on the effect nut consumption has on type 2 diabetes, although available evidence indicates that nuts as part of a healthy diet do not cause weight gain and can have a positive influence on the fatty acid profile of a person with diabetes. This review shows there is a lack of evidence to support the restriction of nut consumption in weight management, indicating that further research is needed to assess the role of nuts in weight management.
Larsson, S.C., A. Wolk, 2007. Magnesium intake and risk of type 2 diabetes: a meta-analysis. J Intern Med. 262(2):208 – 214.
Objective. To assess the association between magnesium intake and risk of type 2 diabetes. Design. Meta-analysis of prospective cohort studies. Data Sources. We retrieved studies published in any language by systematically searching MEDLINE from 1966 to February 2007 and by manually examining the references of the original articles. Study Selection. We included prospective cohort studies reporting relative risks with 95% confidence intervals for the association between magnesium intake and incidence of type 2 diabetes. Results. The seven identified cohort studies of magnesium intake [from foods only (n = 4) or from foods and supplements combined (n = 3)] and incidence of type 2 diabetes included 286 668 participants and 10 912 cases. All but one study found an inverse relation between magnesium intake and risk of type 2 diabetes, and in four studies the association was statistically significant. The overall relative risk for a 100 mg day-1 increase in magnesium intake was 0.85 (95% CI, 0.79-0.92). Results were similar for intake of dietary magnesium (RR, 0.86; 95% CI, 0.77-0.95) and total magnesium (RR, 0.83; 95% CI, 0.77-0.89). There was no evidence of publication bias (P = 0.99). Conclusions. Magnesium intake was inversely associated with incidence of type 2 diabetes. This finding suggests that increased consumption of magnesium rich foods such as whole grains, beans, nuts, and green leafy vegetables may reduce the risk of type 2 diabetes.
Davis, L., W. Stonehouse, D.T. Loots, J. Mukuddem-Petersen, F.H. van der Westhuizen, S.M. Hanekom, J.C. Jerling, 2007. The effects of high walnut and cashew nut diets on the antioxidant status of subjects with metabolic syndrome. Eur J Nutr. 46:155-164.
Background Nut consumption is associated with a protective effect against coronary heart disease, partly due to its high antioxidant content. It is hypothesized that the inclusion of nuts in the diet will improve the antioxidant status of subjects with metabolic syndrome who may be vulnerable to impaired antioxidant status. Aim The effects of high cashew nut and high walnut diets on the antioxidant status of subjects with metabolic syndrome are investigated. Methodology Sixty-four volunteers (29 male and35 female, 45 ± 10y) with metabolic syndrome (diagnosed by using the ATP III criteria) received a prudent control diet, prepared in the metabolic kitchen of the North-West University, Potchefstroom campus (NWU-PC) for a period of 3 weeks (run-in). The participants were grouped according to gender and age and randomized into three groups, receiving either the walnut, cashew nut or the control diets for 8 weeks, while maintaining a stable body weight. Nuts provided 20% of daily energy intake. Fasting blood samples were taken after the run-in period (baseline) and at the end of the intervention period and analyzed for various antioxidant capacity markers. Results The oxygen radical absorbance capacity (ORAC) of the walnut and cashew nut diets were significantly higher than the control diet. Despite this, the walnut and cashew nut diets had no significant effects on serum ORAC, reduced (GSH), oxidized (GSSG) glutathione, GSH:GSSG or diacron reactive metabolites (dRom) (total oxidant status) levels compared to the control group. However, all three groups showed significant improvements in antioxidant status from baseline to end (GSSG and dRom levels decreased; GSG:GSSG ratio and ORAC levels increased). This may be due to a general increased antioxidant intake from the prudent diet compared to the habitual diets. Conclusion Although the inclusion of walnuts and cashew nuts into a prudent diet resulted in an increased antioxidant capacity (ORAC) of the nut diets, compared to the control diet, it did not improve the serum antioxidant profiles of subjects with metabolic syndrome.
Josse, A.R., C.W.C. Kendall, L.S.A. Augustin, P.R. Ellis, D.J.A. Jenkins, 2007. Almonds and postprandial glycemia – a dose-response study. Metabolism. 56(3):400-404.
Almonds, together with other nuts, reduce serum cholesterol levels and may reduce the risk of coronary heart disease. There is much current interest in the relation of coronary heart disease to postprandial events. We have therefore assessed the effects of varying amounts of almonds on the postprandial blood glucose response to a carbohydrate meal. Our aim was to assess the effect of adding almonds to a bread meal. Nine healthy volunteers (2 women, 7 men; mean age, 27.8 years; mean body mass index, 22.9 kg/m2) were randomly fed with 3 test meals and 2 white bread control meals on separate days. Subjects were fed the meals after a 10- to 12-hour overnight fast. Each meal contained 50 g of available carbohydrate from white bread eaten alone or with 30, 60, or 90 g (~1, 2, or 3 oz) of almonds. Capillary fingerprick blood samples for glucose analysis were obtained at 0, 15, 30, 45, 60, 90, and 120 minutes. Glycemic responses were assessed by calculating the incremental area under the 2-hour blood glucose curve. The addition of almonds to white bread resulted in a progressive reduction in the glycemic index of the composite meal in a dose-dependent manner for the 30-g (105.8 ± 23.3), 60-g (63.0 ± 9.0), and 90-g (45.2 ± 5.8) doses of almonds (r = 0.524, n = 36, P = .001). We conclude that, in addition to lowering serum cholesterol levels, almonds may also reduce the glycemic impact of carbohydrate foods with which they are eaten.
Jenkins J. D. A., C. W. C. Kendall, A. R. Josse, S. Salvatore, F. Brighenti, L. S. A. Augustin, P. R. Ellis, E. Vidgen, and A. V. Rao. 2006. Almonds decrease postprandial glycemia, insulinemia, and oxidative damage in healthy individuals. J Nutr. 136:1-6.
Strategies that decrease postprandial glucose excursions, including digestive enzyme inhibition, and low glycemic index diets result in lower diabetes incidence and coronary heart disease (CHD) risk, possibly through lower postprandial oxidative damage to lipids and proteins. We therefore assessed the effect of decreasing postprandial glucose excursions on measures of oxidative damage. Fifteen healthy subjects ate 2 bread control meals and 3 test meals: almonds and bread; parboiled rice; and instant mashed potatoes, balanced in carbohydrate, fat, and protein, using butter and cheese. We obtained blood samples at baseline and for 4 h postprandially. Glycemic indices for the rice (38 ± 6) and almond meals (55 ± 7) were less than for the potato meal (94 ± 11) (P < 0.003), as were the postprandial areas under the insulin concentration time curve (P < 0.001). No postmeal treatment differences were seen in total antioxidant capacity. However, the serum protein thiol concentration increased following the almond meal (15±14 mmol/L), indicating less oxidative protein damage, and decreased after the control bread, rice, and potato meals (-10 ± 8 mmol/L), when data from these 3 meals were pooled (P = 0.021). The change in protein thiols was also negatively related to the postprandial incremental peak glucose (r = -0.29, n = 60 observations, P = 0.026) and peak insulin responses (r = -0.26, n = 60 observations, P = 0.046). Therefore, lowering postprandial glucose excursions may decrease the risk of oxidative damage to proteins. Almonds are likely to lower this risk by decreasing the glycemic excursion and by providing antioxidants. These actions may relate to mechanisms by which nuts are associated with a decreased risk of CHD.
Rajaram, S., J. Sabate’, 2006. Nuts, body weight and insulin resistance. British Journal of Nutrition. 96, Suppl. 2, S79-S86.
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 favorably 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.
Mantzoros, C.S., C.J. Williams, J.E.Manson, J.B. Meigs, F.B. Hu, 2006. Adherence to the Mediterranean dietary pattern is positively associated with plasma adiponectin concentrations in diabetic women. Am J Clin Nutr. 84:328-35.
Background: Although the typical diet of the Mediterranean region has received much recognition over the past several years for its association with substantial health benefits, it remains unknown whether its favorable effects are mediated through changes in adiponectin concentrations. Objective: The objective was to determine whether adherence to a Mediterranean-type diet is associated with higher plasma adiponectin concentrations. Design: This study was a prospective and cross-sectional evaluation of plasma adiponectin concentrations and dietary data from 987 diabetic women from the Nurses’ Health Study who had no history of cardiovascular disease at the time blood was drawn in 1990. Results: Women who scored highest on a 9-point scale that measures adherence to a Mediterranean-type dietary pattern tended to be older, were less likely to be current smokers, had lower body mass indexes and waist circumferences, and had higher total energy intakes, physical activities, and plasma adiponectin concentrations than did women with the lowest scores. Median plasma adiponectin concentrations were 23% higher in women who most closely followed a Mediterranean-type diet than in low adherers after adjustment for age and energy intake (P < 0.01). Body composition, lifestyle, and medical history explained some, but not all, of the observed association between diet and adiponectin concentrations because high adherers tended to have greater adiponectin concentrations than did moderate or low adherers, even after adjustment for these variables. Conclusions: Our data suggest that, of the several components of the Mediterranean dietary pattern score, alcohol, nuts, and whole grains show the strongest association with adiponectin concentrations. Close adherence to a Mediterranean-type diet is associated with higher adiponectin concentrations.
Salas-Salvado’, J., M. Bullo’, A. Pe’rez-Heras, E. Ros, 2006. Dietary fiber, nuts and cardiovascular diseases. British Journal of Nutrition. 96, Suppl. 2, S45-S51.
Dietary fiber has a range of metabolic health benefits. Through a variety of mechanisms, dietary fiber, and the viscous variety in particular, slows down gastric emptying and intestinal transit, decreases the rate of intestinal carbohydrate absorption, and increases fecal bile acid excretion. Therefore, consumption of some types of soluble fiber can enhance satiety, which is associated with a lower BMI, and reduce blood cholesterol and the postprandial glucose response. Surprisingly, the consumption of insoluble fiber from whole grains, though metabolically inert, has been associated with a reduction in the risk of developing coronary heart disease and diabetes in epidemiological studies. The likely reason is that whole grains, like nuts, legumes and other edible seeds, contain many bioactive phytochemicals and various antioxidants. After cereals, nuts are the vegetable foods that are richest in fiber, which may partly explain their benefit on the lipid profile and cardiovascular health.
Gillen, L.J., L.C. Tapsell, C.S. Patch, A. Owen, M. Batterham, 2005. Structured dietary advice incorporating walnuts achieves optimal fat and energy balance in patients with type 2 diabetes mellitus. J Am Diet Assoc. 105:1087-96.
Objective A cardioprotective dietary fat profile is recommended for the treatment of type 2 diabetes. The clinical feasibility of advice strategies targeting specific fatty acid intakes and the extent to which they can be achieved by free-living populations needs to be tested. Walnuts, with high n-3 polyunsaturated fatty acid (PUFA) content, may help optimize fatty acid intakes, but regular consumption might increase total fat and energy intakes. This study examined whether advice that refers to a total dietary pattern inclusive of walnuts would result in low-fat energy-controlled diets with optimal dietary fat proportions for patients with type 2 diabetes mellitus. Research design and methods A parallel-design, controlled trial was completed by 55 free-living men and women with established type 2 diabetes mellitus. Participants were randomly assigned to one of three groups: low-fat (general advice), modified low-fat (total diet advice using exchange lists to differentiate PUFA-rich foods), walnut-specific (modified low fat including 30 g walnuts/day). Dietary intakes and clinical outcomes were measured at baseline, and at 3 and 6 months. Dietary goals were: less than 10% of energy from saturated fat, 7% to 10% of energy from PUFA, adequate n-3 PUFA (≥2.22 g α-linolenic acid, ≥0.65 g eicosapentaenoic acid [EPA]+docosahexaenoic acid [DHA]) and n-6 to n-3 ratio less than 10. The proportion of subjects achieving dietary goals and major food sources of fat were determined. Results At baseline, dietary intakes were not significantly different between groups. No group and few individuals (10%) were consuming adequate PUFA, with meat the main source of dietary fat (22% total dietary fat). At 3 and 6 months, energy and macronutrient intakes were similar among groups. The walnut group, however, was the only group to achieve all fatty acid intake targets (P<.01), and had the greatest proportion of subjects achieving targets (P<.05). Walnuts were the main source of dietary fat (31%) and n-3 PUFA (50%), while 350 g oily fish/day provided a further 17% n-3 PUFA consumed by this group. Conclusions Specific advice for the regular inclusion of walnuts in the context of the total diet helps achieve optimal fat intake proportions without adverse effects on total fat or energy intakes in patients with type 2 diabetes mellitus.
Lopez-Ridaura, R., W.C. Willett, E.B. Rimm, S. Liu, M.J. Stampfer, J.E. Manson, F.B. Hu, 2004. Magnesium intake and risk of type 2 diabetes in men and women. Diabetes Care. 27(1): 134-40.
Objective: To examine the association between magnesium intake and risk of type 2 diabetes. Research Design and Methods: We followed 85,060 women and 42,872 men who had no history of diabetes, cardiovascular disease, or cancer at baseline. Magnesium intake was evaluated using a validated food frequency questionnaire every 2–4 years. After 18 years of follow-up in women and 12 years in men, we documented 4,085 and 1,333 incident cases of type 2 diabetes, respectively. Results:After adjusting for age, BMI, physical activity, family history of diabetes, smoking, alcohol consumption, and history of hypertension and hypercholesterolemia at baseline, the relative risk (RR) of type 2 diabetes was 0.66 (95% CI 0.60–0.73; P for trend<0.001) in women and 0.67 (0.56–0.80; P for trend <0.001) in men, comparing the highest with the lowest quintile of total magnesium intake. The RRs remained significant after additional adjustment for dietary variables, including glycemic load, polyunsaturated fat, trans fat, cereal fiber, and processed meat in the multivariate models. The inverse association persisted in subgroup analyses according to BMI, physical activity, and family history of diabetes. Conclusions: Our findings suggest a significant inverse association between magnesium intake and diabetes risk. This study supports the dietary recommendation to increase consumption of major food sources of magnesium, such as whole grains, nuts, and green leafy vegetables.
