Relation between Dietary Linolenic Fatty Acid and Coronary Heart Disease in the NHLBI Family Heart Study
Epidemiologic studies suggest that higher consumption of alpha linolenic acid, eicosapentaenoic acid, and docosahexanoic acid is associated with lower risk of coronary heart disease (CHD). Little is known about the influence of the linoleic-to-linolenic ratio on the relation of linolenic acid to CHD. We used data collected on 4,406 participants of the NHLBI Family Heart Study (mean age of 52 years)to examine the relation between dietary linolenic acid and prevalent coronary heart disease and to determine if such a relation was influenced by fish consumption and linoleic-to-linolenic ratio. Dietary linolenic acid was assessed by semiquantitative food frequency questionnaire. We used generalized estimating equations to estimate the odds ratios of coronary heart disease across age- and energy-adjusted quintiles of linolenic acid. From the lowest to the highest quintile of linolenic acid, the prevalence odds ratios (95 % CI) of coronary heart disease were 1.00 (referent), 0.77 (0.49-1.21), 0.51 (0.32-0.81), 0.52 (0.33-0.84), and 0.48 (0.30-0.76), respectively, for men (p for trend 0.0009) and 1.00, 0.55 (0.29-1.04), 0.75 (0.41-1.38), 0.43 (0.21-0.88), and 0.40 (0.20-0.82), respectively, for women (p for trend 0.015), controlling for age, energy intake, anthropometric, lifestyle, and metabolic factors. This association was observed across all categories of fish consumption frequency. When stratified by tertiles of linoleic-to-linolenic ratio (ranges of 2.3-8.4, 8.5-11.1, and 11.2-64.0), a statistically significant inverse relation between linolenic acid and CHD was observed only in the lowest tertile of linoleic-to-linolenic ratio (p for trend 0.0001, 0.39, and 0.13, respectively, for the first, second, and third tertile of linoleic-to-linolenic ratio). In conclusion, these data suggest an inverse relation between dietary linolenic acid intake and prevalent coronary heart disease in both sexes, independent of fish consumption. A lower ratio of linoleic-to-linolenic fatty acid might be necessary to observe the benefits of linolenic acid on coronary heart disease.