title: Racial differences between African-American and white women in insulin resistance and visceral adiposity are associated with differences in apoCIII containing apoAI and apoB lipoproteins.
abstract: BACKGROUND
  African-Americans have higher HDL, less visceral adipose tissue (VAT) and lower triglyceride (TG) and apoCIII concentrations than whites, despite being more insulin-resistant. We studied in African-American and white women the influences of insulin resistance and VAT on the apoAI concentrations of two HDL subspecies, one that contains apoCIII that is associated with increased risk of coronary heart disease (CHD) and one that does not have apoCIII that is associated with decreased CHD; and on the apoCIII concentrations of HDL and of the apoB lipoproteins.
  
  
  METHODS
  The participants were 32 women (14 African-Americans, 18 white) of similar age (39 ± 12 vs. 42 ± 11y). Mean BMI was 34 kg/m(2) in the African-Americans compared to 30 in the whites. A standard diet (33% fat, 52% carbohydrate, 15% protein) was provided 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.
  
  
  RESULTS
  After controlling for SI, African-Americans have a higher mean apoAI level in HDL with apoCIII compared with whites (12.9 ± 2.8 and 10.9 ± 2.9 mg/dL, respectively, P = 0.05). SI was associated with higher apoAI in HDL with apoCIII, whereas VAT was not associated with this HDL subspecies. This pattern of results was reversed for apoCIII concentrations in apoB lipoproteins. After adjusting for SI, African-Americans had lower apoCIII in apoB lipoproteins. SI was associated with lower apoCIII in total apoB lipoproteins, whereas VAT was associated with higher apoCIII in all the apoB lipoproteins. Additional adjustment for VAT tended to reduce the difference in apoCIII between the groups.
  
  
  CONCLUSIONS
  African-American women have a higher HDL with apoCIII level than whites when controlled for insulin sensitivity. African-Americans have lower insulin sensitivity. Insulin sensitivity is associated with higher levels of HDL with apoCIII. ApoCIII levels in VLDL are lower in African-American women than whites, also affected by insulin sensitivity which is associated with low apoCIII in VLDL. VAT has a strong association with apoCIII in apoB lipoproteins but not with apoAI in HDL with apoCIII.
  
  
  BACKGROUND
  ClinicalTrials.gov Identifier: NCT00484861.
authors.affiliation: Department of Nutrition, Harvard School of Public Health, 665 Huntington Avenue, Building 1, Room 201, Boston, MA 02115 USA.
authors.forename: Liyun
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Nutrition, Harvard School of Public Health, 665 Huntington Avenue, Building 1, Room 201, Boston, MA 02115 USA ; Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA USA.
authors.forename: Frank M
authors.initials: FM
authors.lastname: Sacks
authors.affiliation: Department of Nutrition, Harvard School of Public Health, 665 Huntington Avenue, Building 1, Room 201, Boston, MA 02115 USA.
authors.forename: Jeremy D
authors.initials: JD
authors.lastname: Furtado
authors.affiliation: Diabetes, Endocrinology and Obesity Branch, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD USA.
authors.forename: Madia
authors.initials: M
authors.lastname: Ricks
authors.affiliation: Nutrition Department, Clinical Center, National Institutes of Health, Bethesda, Maryland.
authors.forename: Amber B
authors.initials: AB
authors.lastname: Courville
authors.affiliation: Diabetes, Endocrinology and Obesity Branch, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD USA.
authors.forename: Anne E
authors.initials: AE
authors.lastname: Sumner
keywords: African-Americans; ApoAI; ApoB lipoproteins; ApoCIII; Coronary heart disease; HDL; Insulin resistance; Visceral adipose tissue