The purpose of this study is to determine whether a daily supplement of 30 grams of walnut is effective in the treatment of metabolic syndrome (MetS).

Metabolic syndrome (MetS), a constellation of metabolic abnormalities including central obesity, dyslipidemia, elevated blood pressure and hyperglycemia, is associated with the development of type 2 diabetes and CVD. It has become one of the major public health challenges in China due to rapidly nutrition transition and the nature of obesity epidemic. Treatment of MetS in China is very important for the prevention of the epidemic of its consequences (such as CVD and type 2 diabetes).

Compelling evidence from recent human studies has demonstrated that diet and lifestyle modifications are effective means in MetS management. Walnut is a complex food source containing high amounts of polyunsaturated fatty acids (PUFA), as well as plant protein, Vitamin E and other substances that may have an impact on health. Therefore, the aim of this study is to investigate the effect of walnut supplementation on the management of MetS in adult Chinese men and women in a randomized, controlled clinical trial. A total of 200 participants with MetS (defined by NCEP-ATPⅢ criteria) will be randomly assigned to a walnut-supplemented diet (30 grams/day) or an isocaloric control diet for 12 weeks. Effects of walnut supplementation will be evaluated by measuring metabolic profile (BMI, blood pressure, total cholesterol, triglyceride, LDL-C and HDL-C, fasting glucose and insulin, HbA1C), inflammatory markers (CRP and IL-6), markers of endothelial function (E-selectin, ICAM-1 and VCAM-1), and fatty acid profile.

Inclusion Criteria:

• With metabolic syndrome. Metabolic syndrome was defined based upon the updated National Cholesterol Education Program Adult Treatment Panel III criteria for Asian-Americans as presenting at least 3 of the following components: 1) waist circumference ≥ 90 cm for men or ≥ 80 cm for women; 2) triglycerides ≥1.7mmol/l; 3) HDL cholesterol <1.03 for men or <1.30 for women; 4) blood pressure ≥130/85 mmHg, or current use of antihypertentive medications; 5) fasting glucose ≥5.6mmol/l or previously diagnosed type 2 diabetes or on oral antidiabetic agents or insulin.
• Being able to comply with the specified feeding conditions
• Being able to eat walnuts
• Being between the ages of 35 and 60 years

Exclusion Criteria:

• Pregnancy or lactation
• Use of insulin
• Severe kidney disease
• Cardiovascular diseases, stroke, cancer and psychological disorders
• Walnut allergies or frequently eating walnuts or other nuts (>90 grams/week)
• Drug or alcohol abuse.