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Open Access Research

ApoC-III and visceral adipose tissue contribute to paradoxically normal triglyceride levels in insulin-resistant African-American women

Anne E Sumner1*, Jeremy D Furtado2, Amber B Courville3, Madia Ricks1, Novie Younger-Coleman4, Marshall K Tulloch-Reid4 and Frank M Sacks2

Author Affiliations

1 Diabetes, Endocrinology and Obesity Branch, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA

2 Harvard School of Public Health, Boston, MA, USA

3 Nutrition Department, Clinical Center, National Institutes of Health, Bethesda, MD, USA

4 Tropical Medicine Research Institute, University of the West Indies, Kingston, Jamaica

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Nutrition & Metabolism 2013, 10:73  doi:10.1186/1743-7075-10-73

Published: 23 December 2013

Abstract

Background

African-Americans are more insulin-resistant than whites but have lower triglyceride (TG) concentrations. The metabolic basis for this is unknown. Our goal was to determine in a cross-sectional study the effect of insulin resistance, visceral adipose tissue (VAT) and the apolipoproteins, B, C-III and E, on race differences in TG content of very low density lipoproteins (VLDL).

Methods

The participants were 31 women (16 African-American, 15 white) of similar age (37 ± 9 vs. 38 ± 11y (mean ± SD), P = 0.72) and BMI (32.4 ± 7.2 vs. 29.3 ± 6.0 kg/m2, P = 0.21). A standard diet (33% fat, 52% carbohydrate, 15% protein) was given for 7 days followed by a test meal (40% fat, 40% carbohydrate, 20% protein) on Day 8. Insulin sensitivity index (SI) was calculated from the minimal model. VAT was measured at L2-3. The influence of race, SI, VAT and apolipoproteins on the TG content of VLDL was determined by random effects models (REM).

Results

African-Americans were more insulin-resistant (SI: 3.6 ± 1.3 vs. 5.6 ± 2.6 mU/L-1.min-1, P < 0.01) with less VAT (75 ± 59 vs. 102 ± 71 cm2, P < 0.01). TG, apoB and apoC-III content of light and dense VLDL were lower in African-Americans (all P < 0.05 except for apoC-III in light VLDL, P = 0.11). ApoE content did not vary by race. In REM, VAT but not SI influenced the TG concentration of VLDL. In models with race, SI, VAT and all apolipoproteins entered, race was not significant but apoC-III and VAT remained significant determinants of TG concentration in light and dense VLDL.

Conclusions

Low concentrations of apoC-III and VAT in African-Americans contribute to race differences in TG concentrations.

Trial registration

ClinicalTrials.gov Identifier: NCT00484861

Keywords:
ApoC-III; Visceral adipose tissue; Triglyceride; Apoliprotein C-III; Visceral adiposity; Insulin resistance; African-Americans; Health disparities