α-Linolenic Acid and Nonfatal Acute Myocardial Infarction

Baylin et al 1 found an inverse relation between ␣-linolenic acid in adipose tissue and nonfatal acute myocardial infarction (AMI).This relation is controversial mainly for nonfatal AMI, 2-4 given that ␣-linolenic acid may be largely antiarrhythmic, but this issue has not been adequately studied in European populations.In America and northern Europe, the major dietary sources of ␣-linolenic acid are rapeseed and canola oils.In Italy, these oils are scarcely consumed, and major dietary sources of ␣-linolenic acid include olive and mixed-seed oils, butter, cheese, and rabbit meat.Thus, although average intake of ␣-linolenic acid in Italy is comparatively high, data in this population with different dietary sources would be interesting.We analyzed the relation between ␣-linolenic acid and nonfatal AMI in a case-control study conducted between 1995 and 1999 in Milan, Italy. 5Cases consisted of 507 patients in hospital with a first episode of nonfatal AMI and 478 control patients admitted to the same hospitals for acute conditions unrelated to AMI risk factors (34% traumas, 30% nontraumatic orthopedic disorders, 14% surgical conditions, and 22% miscellaneous other diseases).Interviews, which were conducted in the hospital using a structured questionnaire, included information on sociodemographic factors, anthropometric variables, tobacco, alcohol, other lifestyle habits, medical history, physical activity, and family history of AMI.Information on diet was based on a validated food frequency section, including intake frequency and portion size of 78 foods and additional questions on the type and amount of fats for seasoning and cooking; the intake of ␣-linolenic acid was computed using an Italian food composition database. 5 The odds ratios (OR) were derived using unconditional multiple logistic regression, including terms for age, sex, and selected AMI confounding factors. 5 Compared with the lowest quintile of intake (Ͻ1.03 g/day) the age-and sex-adjusted OR for the subsequent quintiles of ␣-linolenic acid were 0.70, 0.69, 0.83, and 0.93, and the multivariate OR were 0.71, 0.70, 0.86, and 1.03 (95% CI, 0.55 to 1.92); the upper cut points for the 2nd, 3rd, and 4th quintiles were 1.24, 1.49, and 1.89 (g/day), respectively.In our study, the food frequency questionnaire was satisfactorily valid and reproducible, 5 cases and controls were interviewed in the same hospitals and came from the same geographical area, participation was Ͼ95%, and a different recall of major sources of ␣-linolenic acid intake on the basis of the disease status is unlikely.Thus, these data do not support a relation between ␣-linolenic acid intake and risk of nonfatal AMI in this Italian population.