Effects of a high walnut and high cashew nut diet on selected markers of the metabolic syndrome: a controlled feeding trial

Abstract

We investigated the effects of a high walnut diet and a high unsalted cashew nut diet on selected markers of the metabolic syndrome. In a randomized, parallel, controlled study design, sixty-four subjects having the metabolic syndrome (twenty-nine men, thirty-five women) with a mean age of 45 (SD 10) years and who met the selection criteria were all fed a 3-week run-in control diet. Hereafter, participants were grouped according to gender and age and then randomized into three groups receiving a controlled feeding diet including walnuts, or unsalted cashew nuts or no nuts for 8 weeks. Subjects were required to have lunch at the metabolic ward of the Nutrition Department of the North-West University (Potchefstroom Campus). Both the walnut and the unsalted cashew nut intervention diets had no significant effect on the HDL-cholesterol, TAG, total cholesterol, LDL-cholesterol, serum fructosamine, serum high-sensitivity C-reactive protein, blood pressure and serum uric acid concentrations when compared to the control diet. Low baseline LDL-cholesterol concentrations in the cashew nut group may have masked a possible nut-related benefit. Plasma glucose concentrations increased significantly (P¼ 0·04) in the cashew nut group compared to the control group. By contrast, serum fructosamine was unchanged in the cashew nut group while the control group had significantly increased (P¼ 0·04) concentrations of this short-term marker of glycaemic control. Subjects displayed no improvement in the markers of the metabolic syndrome after following a walnut diet or a cashew nut diet compared to a control diet while maintaining body weight.

A randomized controlled trial of the effects of a prudent diet on cardiovascular risk factors, gene expression, and DNA methylation - the Diet and Genetic Intervention (DIGEST) Pilot study

“…We felt that food provision was the best way to ensure high adherence to the dietary principles, but our design fell short of the conventional approach to a controlled feeding study in a few respects. We were not able to admit participants for a hospital stay or metabolic ward for the duration of the study [23], we could not provide cooked meals for participants [24], and we did not have the facilities to have participants eat at least 1 meal per day on site [22]. Notwithstanding these challenges, provision of food without observation of participant eating occasions or inpatient admission has been shown to result in high adherence to dietary advice in settings similar to ours [21].…”

The impact of pistachio intake alone or in combination with high-carbohydrate foods on post-prandial glycemia

“…In addition, some studies have found a significant reduction in fasting insulin (Casas-Agustench et al, 2011;Tapsell et al 2009) or a significant improvement in insulin resistance (Casas-Agustench et al, 2011). However, none have reported a significant reduction in glycated proteins as a marker of long-term glycemic control (Lovejoy et al, 2002;Scott et al, 2003;Tapsell et al, 2004;Estruch et al, 2006;Mukuddem-Petersen et al, 2007;Casas-Agustench et al, 2011;Tapsell et al, 2009;Ma et al, 2010). In light of recent evidence showing that the combination of the 2 h post-meal glucose levels and fasting blood glucose allow for better estimation of risk both for diabetes and CVD than the fasting blood glucose alone (Sorkin et al, 2005;International Diabetes Federation, 2007); further studies that examine the effect of nuts on post-meal glycemia are warranted.…”

Health Benefits of Nut Consumption

“…A Mediterranean diet supplemented with 30 g of mixed nuts (walnuts, almonds and hazelnuts) per day also showed beneficial effects on the lipid profile compared with advice on a low-fat diet in diabetic and non diabetic participants in the PREDIMED study, a randomized trial of dietary intervention for the primary prevention of cardiovascular disease [80]. Of note, two randomized trials that used cashews or walnuts [81] and mixed nuts [82] compared to control diets in obese patients with the metabolic syndrome failed to show the predictable cholesterol lowering-effect, which supports the findings of the pooled analysis [69] (Figure 3) regarding the inverse association between cholesterol responses to nut feeding and BMI. There may be a mechanistic explanation for decreased lipid responsiveness to dietary intervention in patients with the metabolic syndrome.…”