Effects of Almond Intake on Atherogenic Dyslipidemia of the Metabolic Syndrome

Metabolic syndrome includes a cluster of cardiovascular disease (CVD) risk factors including insulin resistance, abdominal obesity, high blood pressure and an atherogenic lipoprotein phenotype characterized by increased plasma triglycerides, low HDL-C, and increased levels of small LDL particles. While lifestyle intervention remains the cornerstone for its management, the optimal dietary macronutrient distribution for improving blood lipids and CVD risk remains a topic of controversy. While both low carbohydrate diets and weight reduction are effective for managing atherogenic dyslipidemia, long-term compliance is low, and it becomes imperative to identify alternative dietary approaches.

Increased consumption of almonds has been shown to lower LDL-C, an effect that exceeds that predicted from changes in fatty acid intake. However, although LDL-C lowering by almonds has been demonstrated in patients with diabetes, there have been no trials in non-diabetic patients with metabolic syndrome. Moreover, there is limited information of the effects of almond intake on LDL particle subclasses.

The overall objective of the present study is to determine whether lipoprotein measures of CVD risk in individuals with the metabolic syndrome are reduced by almond supplementation in a diet with overall macronutrient content that conforms to current guidelines. Our main hypothesis is that in these individuals, almond consumption can reduce levels of small and medium LDL particles without the need to restrict dietary carbohydrates to levels below those currently recommended.

This hypothesis will be tested by comparing the lipoprotein effects of an almond-supplemented diet (20%E) with those of two reference diets that do not contain almond products: one with similar content of carbohydrate, protein, and fat (standard reference), and the other in which carbohydrate content is reduced by substitution of protein and monounsaturated fat (low-carbohydrate reference).

We will provide the diets for 3 weeks each in a randomized 3-period crossover design to 40 individuals with atherogenic dyslipidemia of the metabolic syndrome. We will test whether the almond supplemented diet will result in lower levels of lipoprotein measures of CVD risk, specifically LDL-C and small and medium LDL particles, compared to either the standard or low-carbohydrate reference diets.