Relationship Between Dietary Linolenic Acid and Coronary Artery Disease in the National Heart, Lung, and Blood Institute Family Heart Study.
Relationship Between Dietary Linolenic Acid and Coronary Artery Disease in the National Heart, Lung, and Blood Institute Family Heart Study.
Year: 2001
Authors: L Djousse, J S Pankow, J H Eckfeldt, A R Folsom, P N Hopkins, M A Province, Y Hong, R C Ellison.
Publication Name: Am. J. Clin. Nutr.
Publication Details: Volume 74; Page 612.
Abstract:
A growing body of evidence has demonstrated that an increase in dietary alpha-linolenic acid (ALA) intake is associated with lower incidence of and mortality from coronary artery disease (CAD). However, the mechanisms by which ALA exerts its protective effects against CAD in humans are not well understood. For instance, researchers are not clear whether the beneficial effects of ALA are modified by the ratio of linoleic to linolenic acid (LA:ALA), by the ratio of polyunsaturated to saturated fatty acids (P:S ratio), or by what degree dietary LA effects the conversion of ALA to longer chain PUFAs EPA and DHA. Thus, using participants from the National Heart, Lung, and Blood Institute (NHLBI) Family Heart Study, the purpose of this study was to assess the relationship between ALA intake and prevalent CAD, as well to examine whether this relationship was influenced by EPA and DHA intake, P:S ratio, and LA:ALA ratio. In addition, a secondary analysis by the researchers assessed the relationship between LA and CAD, after adjusting for ALA intake. A total of 4584 subjects (men=2024, women=2382) from the NHLBI Family Heart Study were assessed using a cross-sectional design. Of these participants, detailed analysis was reported for 4406 white subjects only. The 178 subjects omitted were African American and were not included in the detailed analysis due to limited available data on ALA and CAD in African Americans, as well as a higher prevalence of diabetes mellitus, smoking, mean systolic blood pressure, and higher HDL-cholesterol concentrations in this race in comparison to the white participants. The researchers believed that including data on the African American subjects would result in unstable estimations in stratified analyses. Of the remaining participants dietary assessment was carried out via a semi quantitative food-frequency questionnaire, and for each sex, age-and energy-adjusted quintiles for ALA were created. In addition, logistic regression was used to estimate prevalent odds ratios for CAD. Results demonstrated that after adjustment for age, linoleic acid, anthropometric, lifestyle, and metabolic factors, the prevalence odds ratios of CAD for lowest to highest quintile of ALA were 1.0, 0.77, 0.61, 058, and 0.60 for men and 1.0, 0.57, 0.52, 0.30, 0.42 for women. Thus, the researchers observed an inverse relationship between age and energy adjusted ALA intake and CAD in both men and women. In addition, linoleic acid intake was found to be inversely associated with prevalence odds ratio of CAD independent of ALA intake. Finally, the data suggest a synergistic relationship between both ALA and linoleic acid in terms of prevalence odds ratio of CAD. In conclusion, results from this study are consistent with previous findings that demonstrated that a higher intake of ALA possesses cardioprotective effects. Possible mechanisms for the protective effects of ALA may be attributed to ALA’s ability to raise the threshold for arrhythmia, as well as its conversion to EPA and DHA. EPA has been reported to have anti-thrombotic effects, lowers plasma triacylglyerol concentrations, and attenuates inflammation, all of which are important in protection against CAD. However, further studies are required to determine the exact mode of action.
