Associations between plasma polyunsaturated fatty acids, plasma stearoyl‐CoA desaturase indices and body fat

Stearoyl‐CoA desaturase (SCD)‐1 deficient mice are resistant to obesity and plasma SCD indices are related to obesity in humans. Both n‐3 and n‐6 polyunsaturated fatty acids (PUFA) regulate expression of the SCD enzymes. Whether higher plasma PUFA were associated with lower SCD indices in humans was examined.

Population‐based study of 2,021 elderly subjects from the Hordaland Health Study. Using multivariate linear regression, the cross‐sectional associations among plasma PUFA, estimated SCD indices (from fatty acid profiles in plasma total lipids), and fat mass measured by dual‐energy X‐ray absorptiometry were explored. Two plasma SCD indices were used: SCD‐16 (16:1n‐7/16:0) and SCD‐18 (18:1n‐9/18:0).

Plasma total, n‐6 and n‐3 PUFA were inversely associated with both SCD indices (P < 0.001 for all). Among the individual PUFA, 18:2n‐6 showed the strongest association with SCD‐16 (partial r = −0.59, P < 0.001) followed by 20:5n‐3 (partial r = −0.13; P < 0.001). Plasma total, n‐6 and n‐3 PUFA were inversely associated with body fat (P < 0.001 for all); the associations were markedly attenuated following adjustment for SCD‐16.

The epidemiological data are in line with animal studies and suggest that PUFA may decrease SCD1 activity in humans, with possible reduction in body fat.