Dietary linolenic acid and fasting glucose and insulin: the National Heart, Lung, and Blood Institute Family Heart Study.

OBJECTIVE: To assess whether dietary linolenic acid is associated with fasting insulin and glucose. RESEARCH METHODS AND PROCEDURES: In a cross-sectional design, we studied 3993 non-diabetic participants of the National Heart, Lung, and Blood Institute Family Heart Study 25 to 93 years of age. Linolenic acid was assessed through a food frequency questionnaire, and laboratory data were obtained after at least a 12-hour fast. We used generalized linear models to calculate adjusted means of insulin and glucose across quartiles of dietary linolenic acid.
RESULTS: From the lowest to the highest sex-specific quartile of dietary linolenic acid, means +/- standard error for logarithmic transformed fasting insulin were 4.06 +/- 0.02 (reference), 4.09 +/- 0.02, 4.13 +/- 0.02, and 4.17 +/- 0.02 pM, respectively (trend, p < 0.0001), after adjustment for age, sex, energy intake, waist-to-hip ratio, smoking, and high-density lipoprotein-cholesterol. When dietary linolenic acid was used as a continuous variable, the multivariable adjusted regression coefficient was 0.42 +/- 0.08. There was no association between dietary linolenic acid and fasting glucose (trend p = 0.82). DISCUSSION: Our data suggest that higher consumption of dietary linolenic acid is associated with higher plasma insulin, but not glucose levels, in non-diabetic subjects. Additional studies are needed to assess whether higher intake of linolenic acid results in an increased insulin secretion and improved glucose use in vivo.