British Journal of Nutrition

Full Papers

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

Janine Mukuddem-Petersena1a2 c1, Welma Stonehouse (Oosthuizen)a1a3, Johann C. Jerlinga1, Susanna M. Hanekoma1 and Zelda Whitea1

a1 School of Physiology, Nutrition and Consumer Science, North-West University (Potchefstroom Campus), Potchefstroom, South Africa

a2 School of Computer, Mathematical and Statistical Sciences, North-West University (Potchefstroom Campus), Potchefstroom, South Africa

a3 Institute of Food, Nutrition and Human Health, Massey University (Albany Campus), North Shore, Auckland, New Zealand


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 (P = 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 (P = 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.

(Received July 18 2006)

(Revised December 20 2006)

(Accepted January 03 2007)


Abbreviations: ATP III, National Cholesterol Education Program's Adult Treatment Panel III; BP, blood pressure; %E, percentage of total energy; HDL-C, HDL-cholesterol; LDL-C, LDL-cholesterol; S-hs CRP, serum high-sensitivity C-reactive protein; TC, total cholesterol