Effects of Almond Intake on Atherogenic Lipoprotein Particles

Effects of Almond Intake on Atherogenic Lipoprotein Particles in Individuals With Increased Abdominal Adiposity

Increased abdominal adiposity is a key feature of metabolic syndrome, which describes a cluster of cardiovascular disease (CVD) risk factors that also includes insulin resistance, 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 managing obesity and metabolic syndrome, 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 abdominal obesity. 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 increased abdominal adiposity 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 increased abdominal adiposity. 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.

Study Overview

• Status: Completed
• Conditions: Dyslipidemia; Obesity, Abdominal
• Intervention / Treatment: Other: Standard reference diet; Other: Almond supplemented diet; Other: Low carbohydrate reference diet

• Study Type: Interventional
• Enrollment (Actual): 24
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • California
    • Berkeley, California, United States, 94705
      • Cholesterol Research Center

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 20 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Age 20 or older
• Increased abdominal adiposity as defined by waist circumference ≥102 for men or ≥88 for women.
• 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) > 38 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 > 50mg/dl and > 500 mg/dl
• Abnormal thyroid stimulating hormone (TSH) levels.
• Pregnant or breast-feeding

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Single

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Standard Reference Diet	Other: Standard reference diet; 50% energy as carbohydrate, 15% energy as protein, 35% energy as total fat
Experimental: Almond Supplemented Diet	Other: Almond supplemented diet; 50% energy as carbohydrate, 15% energy as protein, 35% energy as total fat, 20% energy from almonds
Active Comparator: Low Carbohydrate Reference Diet	Other: Low carbohydrate reference diet; 26% energy from carbohydrate, 29% energy from protein, 45% energy from total fat

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Total and LDL cholesterol	Change in total and LDL cholesterol between each of the 3 test diets	3 weeks, 8 weeks, 13 weeks
Change in small and medium LDL particles	Change in small and medium LDL particles between each of the 3 test diets	3 weeks, 8 weeks, and 13 weeks
Change in apolipoprotein B	Change in apolipoprotein B between each of the 3 test diets	3 weeks, 8 week, 13 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in total/HDL-cholesterol ratio	Change in total/HDL-cholesterol ratio between each of the 3 test diets	3 weeks, 8 weeks, 13 weeks
Change in LDL peak particle diameter	Change in LDL peak particle diameter between each of the 3 test diets	3 weeks, 8 week, 13 weeks
Change in plasma triglycerides	Change in plasma triglycerides between each of the 3 test diets	3 weeks, 8 weeks, 13 weeks
Change in HDL-cholesterol	Change in HDL-cholesterol between each of the 3 test diets	3 weeks, 8 weeks, 13 weeks
Change in large HDL particles	Change in large HDL particles between each of the 3 test diets	3 weeks, 8 weeks, 13 weeks
Change in apolipoprotein AI	Change in apolipoprotein AI between each of the 3 test diets	3 weeks, 8 weeks, 13 weeks
Change in HOMA-IR	Change in homeostatic model assessment insulin resistance (HOMA-IR) after each of the 3 test diets	3 weeks, 8 weeks, 13 weeks

Collaborators and Investigators

• Sponsor: UCSF Benioff Children's Hospital Oakland
• Collaborators: Almond Board of California

Publications and helpful links

General Publications

• Williams PT, Bergeron N, Chiu S, Krauss RM. A randomized, controlled trial on the effects of almonds on lipoprotein response to a higher carbohydrate, lower fat diet in men and women with abdominal adiposity. Lipids Health Dis. 2019 Apr 3;18(1):83. doi: 10.1186/s12944-019-1025-4.

Study record dates

Study Major Dates

• Study Start: April 1, 2013
• Primary Completion (Actual): February 1, 2016
• Study Completion (Actual): April 1, 2016

Study Registration Dates

• First Submitted: April 26, 2012
• First Submitted That Met QC Criteria: February 13, 2013
• First Posted (Estimate): February 15, 2013

Study Record Updates

• Last Update Posted (Actual): November 6, 2017
• Last Update Submitted That Met QC Criteria: October 31, 2017
• Last Verified: October 1, 2017

More Information

Terms related to this study

• Keywords: Cholesterol; Diet; Carbohydrate; Almond
• Additional Relevant MeSH Terms: Metabolic Diseases; Overnutrition; Nutrition Disorders; Lipid Metabolism Disorders; Obesity; Dyslipidemias; Obesity, Abdominal
• Other Study ID Numbers: MM2222