Effects of Almond Intake on Atherogenic Dyslipidemia of the Metabolic Syndrome

• Change in Total and LDL cholesterol [ Time Frame: 3 weeks, 8 weeks, 13 weeks ] [ Designated as safety issue: No ]
  Change in total and LDL cholesterol between each of the 3 test diets
• Change in small and medium LDL particles [ Time Frame: 3 weeks, 8 weeks, and 13 weeks ] [ Designated as safety issue: No ]
  Change in small and medium LDL particles between each of the 3 test diets
• Change in apolipoprotein B [ Time Frame: 3 weeks, 8 week, 13 weeks ] [ Designated as safety issue: No ]
  Change in apolipoprotein B between each of the 3 test diets

• Change in total/HDL-cholesterol ratio [ Time Frame: 3 weeks, 8 weeks, 13 weeks ] [ Designated as safety issue: No ]
  Change in total/HDL-cholesterol ratio between each of the 3 test diets
• Change in LDL peak particle diameter [ Time Frame: 3 weeks, 8 week, 13 weeks ] [ Designated as safety issue: No ]
  Change in LDL peak particle diameter between each of the 3 test diets
• Change in plasma triglycerides [ Time Frame: 3 weeks, 8 weeks, 13 weeks ] [ Designated as safety issue: No ]
  Change in plasma triglycerides between each of the 3 test diets
• Change in HDL-cholesterol [ Time Frame: 3 weeks, 8 weeks, 13 weeks ] [ Designated as safety issue: No ]
  Change in HDL-cholesterol between each of the 3 test diets
• Change in large HDL particles [ Time Frame: 3 weeks, 8 weeks, 13 weeks ] [ Designated as safety issue: No ]
  Change in large HDL particles between each of the 3 test diets
• Change in apolipoprotein AI [ Time Frame: 3 weeks, 8 weeks, 13 weeks ] [ Designated as safety issue: No ]
  Change in apolipoprotein AI between each of the 3 test diets
• Change in HOMA-IR [ Time Frame: 3 weeks, 8 weeks, 13 weeks ] [ Designated as safety issue: No ]
  Change in homeostatic model assessment insulin resistance (HOMA-IR) after each of the 3 test diets

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.

• Metabolic Syndrome
• Dyslipidemia
• Hypertriglyceridemia

• Other: Standard reference diet
  50% energy as carbohydrate, 15% energy as protein, 35% energy as total fat
• Other: Almond supplemented diet
  50% energy as carbohydrate, 15% energy as protein, 35% energy as total fat, 20% energy from almonds
• Other: Low carbohydrate reference diet
  26% energy from carbohydrate, 29% energy from protein, 45% energy from total fat

• Active Comparator: Standard Reference Diet
  Intervention: Other: Standard reference diet
• Experimental: Almond Supplemented Diet
  Intervention: Other: Almond supplemented diet
• Active Comparator: Low Carbohydrate Reference Diet
  Intervention: Other: Low carbohydrate reference diet

Inclusion Criteria:

• Age 20 or older
• Plasma triglycerides ≥ 150mg/dL and plasma HDL-C < 40 mg/dL (men) or < 50 mg/dL (women) and at least one additional metabolic syndrome criteria: waist circumference > 102 cm (men) or > 88 cm (women), blood pressure ≥ 130/≥ 85 mmHg, or fasting glucose ≥ 110mg/dL.
• Fasting blood sugar (FBS) < 126 mg/dl
• Weight stable for > 3 months.

Exclusion Criteria:

• History of coronary heart disease, cerebrovascular disease, peripheral vascular disease, bleeding disorder, liver or renal disease, diabetes, lung disease, HIV, or cancer (other than skin cancer) in the last 5 years.
• Taking hormones or drugs known to affect lipid metabolism or blood pressure.
• Systolic blood pressure > 160 mm Hg and diastolic blood pressure > 95 mm Hg.
• Body mass index (BMI) > 35 kg/m2
• User of nicotine products or recreational drugs
• Refusal to abstain from alcohol or dietary supplements during the study.
• Total- and LDL-C > 95th percentile for sex and age.
• Fasting triglycerides > 500 mg/dl
• Abnormal thyroid stimulating hormone (TSH) levels.
• Pregnant or breast-feeding