Abstract 3899: Alpha-linolenic Acid, Delta-6 Desaturase Gene Polymorphism, and Risk of Nonfatal Myocardial Infarction
A common deletion [T/−] in the promoter of delta-6 desaturase (FADS2), the rate-limiting step in the conversion of alpha-linolenic acid and linoleic acid into long-chain polyunsaturated fatty acids may affect their biosynthetic pathway and consequently modify the effect of alpha-linolenic acid on myocardial infarction (MI). We conducted a study among 1694 cases of a first nonfatal acute MI matched by age, sex and area of residence to 1694 population-based controls. Polyunsaturated fatty acids were quantified by gas-liquid chromatography from plasma and adipose tissue samples. Least square means from generalized linear models, and odds ratios (OR) and 95% confidence intervals (CI) from multiple conditional logistic regression models were estimated. The prevalence of the variant T/− allele was 48%. Eicosapentaenoic acid, gamma-linolenic acid, and arachidonic acid, decreased in adipose tissue and plasma with the number of copies of the variant allele with a monotonic trend (all p-value <0.05). The FADS2 deletion was not associated to MI and did not modify the association between adipose tissue alpha-linolenic acid and risk of MI. When the analysis was restricted to palm oil users (an oil naturally low in alpha-linolenic acid) a significant interaction (p=0.047) between alpha-linolenic acid, FADS2 and risk of MI was observed. Alpha-linolenic acid was protective only among the T/T carriers OR=0.39, 95%CI=(0.21, 0.73), but not among T/− or −/− (OR=0.86, 95%CI=(0.55, 1.34 and OR=0.96, 95%CI=(0.53, 1.76). The FADS2 deletion may prevent the conversion of alpha-linolenic acid into long chain polyunsaturated fatty acids and attenuate the protective association between alpha-linolenic acid and MI, among people with low intake of alpha-linolenic acid. Further studies on this polymorphism and others in the FADS2 gene are warranted to reassess the effect of n-3 and n-6 polyunsaturated fatty acids on coronary heart disease. These future studies will be of special importance in those populations where the intake of long-chain n-3 fatty acids from fish is very low.