Fatty Acid Metabolism Differs by Ethnicity

Julia H Goedecke, Elin Chorell, Paul J van Jaarsveld, Ulf Risérus, Tommy Olsson
The Journal of Clinical Endocrinology & Metabolism, Volume 106, Issue 1, January 2021, Pages e140–e151
https://doi.org/10.1210/clinem/dgaa696

Abstract

Purpose

Genetic differences in desaturase genes and consequently fatty acid metabolism have been reported. The aims were to examine ethnic differences in serum fatty acid composition and desaturase indices, and assess the ethnic-specific associations with insulin sensitivity (IS) and liver fat in black and white South African (SA) women.

Methods

In this cross-sectional study including 92 premenopausal black (n = 46) and white (n = 46) SA women, serum fatty acid composition was measured in cholesteryl ester (CE) and nonesterified fatty acid (NEFA) fractions. Desaturase activities were estimated as product-to-precursor ratios: stearoyl-CoA desaturase-1 (SCD1-16, 16:1n-7/16:0); Δ-5 desaturase (D5D, 20:4n-6/20:3n-6), and Δ-6 desaturase (D6D, 18:3n-6/18:2n-6). Whole-body IS was estimated from an oral glucose tolerance test using the Matsuda index. In a subsample (n = 30), liver fat and hepatic IS were measured by ¹H-magnetic resonance spectroscopy and hyperinsulinemic euglycemic clamp, respectively.

Results

Despite lower whole-body IS (P = .006), black women had higher CE D5D and lower D6D and SCD1-16 indices than white women (P < .01). CE D6D index was associated with lower IS in white women only (r = –0.31, P = .045), whereas D5D index was associated with higher IS in black women only (r = 0.31, P = .041). In the subsample, D6D and SCD1-16 indices were positively and D5D was negatively associated with liver fat (P < .05). Conversely, CE SCD1-16 was negatively associated with hepatic IS (P < .05), but not independently of liver fat.

Conclusions

Ethnic differences in fatty acid–derived desaturation indices were observed, with insulin-resistant black SA women paradoxically showing a fatty acid pattern typical for higher insulin sensitivity in European populations.

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