Abstract
This study determined the associations of serum insulin and estrogen with fatty acid
composition, fatty acid product/substrate ratios used as indexes of desaturase enzyme
function, and platelet aggregation in obese and lean women. Thirty women were classified
as obese (n = 8) or lean (n = 21) based on body mass index. Obese women were characterized
by higher insulin levels (p < 0.05) but fasting glucose levels did not differ (p >
0.05) from lean women. Insulin positively correlated with increased C20:4n6/C18:3n6
(index of Δ5-desaturase) (p < 0.05) and C20:4n6/C18:2n6 (index of overall n6 pathway
activity) (p < 0.01) in serum, and the n6 pathway in platelets (p < 0.01), but there
was no correlation for insulin with platelet C18:3n6/C18:2n6 (index of Δ6-desaturase
activity). Insulin was also positively related (p < 0.01) to aggregation as measured
by impedance and negatively related to lag time (p < 0.05). Platelets of obese women
aggregated more (p < 0.05) compared to lean women and began aggregating faster (p
< 0.05), suggesting the possibility that the obese women were at greater risk for
enhanced blood clotting. Plasma estrogen was correlated with age (p < 0.05) but not
for other variables studied (p > 0.05). Insulin, but not estrogen, appears to influence
desaturase activity, as demonstrated by increased desaturase function associated with
hyperinsulinemia in obese women.
Key words
Desaturase - Insulin - Estrogen - Obesity
