The Effects of Chronic Almond Consumption in Adults with Different Body Fat Distributions on Carbohydrate and Lipid Metabolism

Stephanie R Hunter, Purdue University

Abstract

Acute feeding trials indicate that almond consumption can lower the glycemic response to a meal, evoke a second meal effect, and help lower glycemia throughout the day, especially when they are consumed at breakfast or as an afternoon snack. However, the literature is mixed with regard to the effect of almond consumption on HbA1c, hampering the acceptance of a beneficial role for almond consumption on glycemic control. Different body fat distributions carry different risks for insulin resistance, independent of body weight, and thus may respond differently to dietary interventions. Testing people with different body fat distributions may be a reason for the inconsistent evidence on almond consumption on HbA1c. This dissertation had two primary aims. The first primary aim was to determine the acute effect of almond consumption on the glycemic response to a meal tolerance test in adults with different body fat distributions. The second primary aim was to determine the chronic effect of almond consumption on fasting glucose, insulin, HbA1c, triglycerides, total cholesterol, LDL cholesterol, HDL cholesterol, body weight, body composition, appetite, and calculated HOMA-IR and HOMA-%β in adults with different body fat distributions. A secondary objective of this dissertation was to determine the effect of substituting almonds, a wholesome snack food, for a more traditional, less nutrient dense snack food on total diet quality. A 6-month randomized, controlled trial in 134 adults was conducted. Participants were randomly assigned to the almond or control treatment group based on their body fat distribution. Participants in the almond treatment group consumed 42.5 grams of almonds with their breakfast and as their afternoon snack every day, and were instructed not to consume any other nuts or nut products. Participants in the control treatment group continued their habitual breakfast and afternoon snack routines, but were instructed not to consume any nuts or nut products. Body composition was measured and blood samples were collected for determination of fasting glucose, insulin, HOMA-IR, HOMA-%β, HbA1c, triglycerides, total cholesterol, LDL cholesterol, HDL cholesterol, and meal stimulated glucose and insulin at months 0 and 6. Appetite and dietary intake data to assess total diet quality were collected at months 0, 2, 4 and 6 as was a blood sample for compliance testing. Body weight was measured every 2 weeks. An intention-to-treat and complier linear mixed model analysis with Bonferroni correction for pairwise comparisons was performed. The findings from this dissertation research demonstrate that compared to participants in the control treatment group who consumed their habitual breakfast and afternoon snacks without nuts or nut products, consumption of almonds every day for 6 months has no effect on body weight. However, participants with high android subcutaneous adipose tissue in the almond treatment group had a decrease in android fat mass percentage and an increase in android lean mass percentage, and tended to have an attenuation in gain of visceral adipose tissue mass compared to participants with high android subcutaneous adipose tissue in the control treatment group, but there were no effects in participants with high android visceral adipose tissue or high gluteal femoral adipose tissue. Participants who consumed almonds for 6 months had a higher seafood and plant protein score and fatty acid scores compared to the participants in the control treatment group, and total diet quality, measured by total HEI score, increased during the intervention compared to baseline in participants in the almond treatment group, but total diet quality was not higher in participants in the almond treatment group compared to participants in the control treatment group over time. There were no differences in appetite, fasting or meal stimulated glucose and insulin, HbA1c, fasting triglycerides, LDL cholesterol, HDL cholesterol, or HOMA-IR and HOMA-%β between participants in the almond and control treatment groups for any body fat distribution. Thus, testing people with different body fat distributions may not explain the mixed evidence of almond consumption on HbA1c.

Degree

Ph.D.

Advisors

Mattes, Purdue University.

Subject Area

Medicine|Pharmaceutical sciences|Public health

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