Background and aim: Homocysteine, a methionine metabolite, is suggested to be a risk factor for cardiovascular diseases (CVD). To date, the effects of dietary intake of methionine, the key amino acid in homocysteine metabolism, on CVD have not been studied. Our aim was to examine the effects of dietary methionine intake on the risk of acute coronary events.
Methods and results: We examined the effects of dietary methionine intake, assessed with 4-d food record, on acute coronary events in a prospective cohort study consisting of 1981 coronary disease free men from eastern Finland, aged 42-60 years at baseline in 1984-89, in the Kuopio Ischaemic Heart Disease Risk Factor (KIHD) Study. During an average follow-up time of 14.0 years, 292 subjects experienced an acute coronary event. In a Cox proportional hazards model adjusting for age, examination years, BMI, urinary nicotine metabolites and protein intake (excluding methionine) the relative risks of acute coronary event in the three highest quarters of dietary methionine intake were 1.31 (95% CI: 0.92, 1.86), 1.31 (95% CI: 0.88, 1.96) and 2.08 (95% CI: 1.31, 3.29) as compared with the lowest quarter. Further adjustments did not change the results. However, opposite association was observed with total protein intake, which tended to decrease the risk.
Conclusions: The main finding of this study is that long-term, moderately high dietary methionine intake may increase the risk of acute coronary events in middle-aged Finnish men free of prior CHD. More prospective research is needed to confirm the role of dietary methionine in the development of CVD, and whether its effects are independent of homocysteine.