The triglyceride paradox is related to lipoprotein size, visceral adiposity and stearoyl-CoA desaturase activity in black vs. white women

Authors: CHUNG, STEPHANIE - National Institutes Of Health (NIH); CRAVALHO, CELESTE - National Institutes Of Health (NIH); MEYERS, ABBY - National Institutes Of Health (NIH); COURVILLE, AMBER - National Institutes Of Health (NIH); YANG, SHANNA - National Institutes Of Health (NIH); MATTHAN, NIRUPA - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; MABUNDO, LILIAN - National Institutes Of Health (NIH); SAMPSON, MAUREEN - National Institutes Of Health (NIH); OUWERKERK, RONALD - National Institutes Of Health (NIH); GHARIB, AHMED - National Institutes Of Health (NIH); LICHTENSTEIN, ALICE - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; REMALEY, ALAN - National Institutes Of Health (NIH); SUMNER, ANNE - National Institutes Of Health (NIH)

Submitted to: Circulation Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/2/2019
Publication Date: 10/18/2019
Citation: Chung, S.T., Cravalho, C.K., Meyers, A.G., Courville, A.B., Yang, S., Matthan, N.R., Mabundo, L., Sampson, M.L., Ouwerkerk, R., Gharib, A.M., Lichtenstein, A.H., Remaley, A.T., Sumner, A.E. 2019. The triglyceride paradox is related to lipoprotein size, visceral adiposity and stearoyl-CoA desaturase activity in black vs. white women. Circulation Research. 126(1):94-108. https://doi.org/10.1161/CIRCRESAHA.119.315701.
DOI: https://doi.org/10.1161/CIRCRESAHA.119.315701

Interpretive Summary: In black women, triglyceride levels are normal in the presence of insulin resistance (diminished response to insulin). In white women, triglyceride levels are elevated in the presences of insulin resistance. Potential reasons for the metabolic advantage in black compared to white women may have to do with body fat distribution and/or differences in the body's ability to process dietary sugar. The aim of this study was to compare the response of black and white women to a high glucose drink. We found the drink resulted in black compared to white women having lower fasting and postprandial large, medium and small concentrations of plasma particles that carry triglyceride. In contrast, they were more insulin resistant. Lower fat in the abdominal region and lower activity of the enzyme that converts saturated to monounsaturated fatty acids appeared to be important mediators of the lower triglyceride concentrations, translating to a potential metabolic advantage. These findings support the value of additional investigation to determine whether the differences observed are significant mediators of different cardiometabolic disease risks in black and white women.

Technical Abstract: Rationale: In black women, triglycerides are paradoxically normal in the presence of insulin resistance. This relationship may be explained by race-related differences in central adiposity and stearoyl-CoA enzyme activity index. Objective: To compare fasting and postprandial triglyceride-rich lipoprotein particle (TRLP) concentrations and size in black compared to white pre- and post-menopausal women and determine the relationship between TRLP subfractions and whole-body insulin sensitivity, hepatic and visceral fat, and SCD-116 levels. Methods and Results: In 122 federally employed women without diabetes, 73 black (58 African American and 15 African immigrant) and 49 white; age 44+/-10 (mean+/-SD); BMI 30.0+/-5.6 kg/m^2 we measured lipoprotein subfractions using nuclear magnetic resonance. Hepatic fat was measured by proton MRS, insulin sensitivity index (SI) calculated by minimal modeling from a frequently-sampled intravenous glucose test, RBC fatty acid profiles by gas chromatography were used to estimate SCD-1 indices. Hepatic fat, SI, and SCD-1 were similar in black women and lower than in whites, regardless of menopausal status (P<0.01). Fasting and postprandial large, medium and small TRLPs, but not very small TRLPs, were lower in blacks (P<0.01). Fasting large, medium and very small TRLPs correlated with SI and SCD-1 activity in both groups (all r>/=0.4, P<0.01). In multivariate models, visceral fat, age, and SCD-1 were associated with total fasting TRLP concentrations (adjR^2= 0.39, P<0.01). Black women had smaller postprandial changes in large and medium TRLPs (P<0.01). Conclusions: Lower visceral fat and SCD-1 activity may contribute to the paradoxical association of lower fasting and postprandial TRLP subfractions despite greater insulin resistance in black compared to white pre- and post-menopausal 54 women. Similar concentrations of very small TRLPs are related to insulin resistance and could be important mediators of cardiometabolic disease risk in women.