Adipose tissue fatty acids and risk of myocardial infarction - a case-control study

Objectives: To study the association between content in adipose tissue of v ery long-chain n-3 fatty acids, tr-ans fatty acids, linoleic acid and alpha -linolenic acid and risk of a first myocardial infarction. Design and subjects: A case-control design among 100 patients and 98 popula tion controls both men and postmenopausal women, age 45-75 y. Adipose tissu e fatty acids were determined by gas-liquid chromatography. Intake data wer e obtained through interview using a validated food frequency questionnaire . Results: Dietary intake and adipose tissue content of the fatty acids studi ed correlated significantly. Adipose tissue contents of eicosapentaenoic ac id (20:5n-3), docosapentaenoic acid (22:5n-3) and docosahexaenoic acid (22: 6n-3) were significantly lower while those of trans fatty acids, linoleic a nd alpha-linolenic acid were significantly higher in patients than in contr ols. Age and sex adjusted odds ratios (OR) were significantly reduced with increasing quintiles of very long-chain n-3 fatty acids, thus the OR in the fifth compared to the first quintile was 0.23 (95% CI 0.08-0.70). After fu rther adjustment for waist-to-hip ratio, smoking, family history of CHD and content of trans fatty acids, the OR in the highest quintile was 0.17 (95% CI 0.04-0.76) and the P for trend 0.016. Age and sex adjusted OR was incre ased in the fifth compared to the first quintile of trans fatty acids (OR 2 .81, 95% CI 1.16-6.84), linoleic acid (OR 2.10, 95% CI 0.87-5.07) and alpha -linolenic acid (OR 1.96, 95% CI 0.83-4.61), and P for trend was 0.002. 0.0 05 and 0.020, respectively. The trends remained significant after adjustmen t for waist-to-hip ratio, smoking, and family history of coronary heart dis ease. Trans fatty acids, linoleic acid and alpha-linolenic acid in adipose tissue were strongly correlated, indicating a common source, most likely ma rgarine. When each of these fatty acid species were adjusted for the two ot hers the trends were no longer significant. Conclusion: Intake of very long-chain n-3 Fatty acids as reflected in adipo se tissue content is inversely associated with risk of myocardial infarctio n. Trans fatty acids, linoleic and alpha-linolenic acid were intercorrelate d and associated with increased risk. It is suggested that the increased ri sk may be connected to trans fatty acids or to some other factor associated with margarine consumption.