Association between the intake of α-linolenic acid and the risk of CHD

Abstract

The intake of the mainly plant-derived n-3 PUFA α-linolenic acid (ALA) has been reported to be associated with a lower risk of CHD. However, the results have been inconsistent. Therefore, the objective of the present study was to examine the association between the intake of ALA and the risk of CHD. Potential effect modification by the intake of long-chain n-3 PUFA (n-3 LCPUFA) was also investigated. Data from eight American and European prospective cohort studies including 148 675 women and 80 368 men were used. The outcome measure was incident CHD (CHD event and death). During 4-10 years of follow-up, 4493 CHD events and 1751 CHD deaths occurred. Among men, an inverse association (not significant) between the intake of ALA and the risk of CHD events and deaths was observed. For each additional gram of ALA consumed, a 15 % lower risk of CHD events (hazard ratios (HR) 0·85, 95 % CI 0·72, 1·01) and a 23 % lower risk of CHD deaths (HR 0·77, 95 % CI 0·58, 1·01) were observed. No consistent association was observed among women. No effect modification by the intake of n-3 LCPUFA was observed.

Figure 1

Study-specific and combined risk of coronary heart (CHD) events for each additional g/d intake of alpha-linolenic acid (ALA) in men and women in the Pooling Project of Cohort Studies on Diet and Coronary Disease. Data are given as hazard ratios (HR) and 95% confidence intervals (CI) by using Cox proportional hazards regression. The multivariate model was adjusted for age at baseline and the calendar year in which the baseline questionnaire was returned, smoking habits, body mass index, physical activity, educational level, history of hypertension, alcohol intake, total energy intake, fibre intake, monounsaturated fatty acid, trans fatty acid, saturated fatty acid, linoleic acid and n-3 LCPUFA intake. Within each study HRs with 95% CI for the incidence of a CHD event and CHD death were calculated by using Cox proportional hazard regression. The squares and horizontal lines represent the study-specific HRs and 95% CI, respectively. The area of the squares reflects the study-specific weight. The “total square” represents the pooled HRs and 95% CI. ARIC, Atherosclerosis risk in Communities Study; ATBC, Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study; FMC, Finnish Mobile Clinic Health Examination Survey; HPFS, Health Professionals Follow-up Study; IWHS, Iowa Women's Health Study; NHS, Nurses' Health Study; VIP, Västerbotten Intervention Program; WHS, Women's Health Study.

Figure 2

Study-specific and combined risk of coronary heart (CHD) death for each additional g/d intake of alpha-linolenic acid (ALA) in men and women in the Pooling Project of Cohort Studies on Diet and Coronary Disease. Data are given as hazard ratios (HR) and 95% confidence intervals (CI) by using Cox proportional hazards regression. The multivariate model was adjusted for age at baseline and the calendar year in which the baseline questionnaire was returned, smoking habits, body mass index, physical activity, educational level, history of hypertension, alcohol intake, total energy intake, fibre intake, monounsaturated fatty acid, trans fatty acid, saturated fatty acid, linoleic acid and n-3 LCPUFA intake. Within each study HRs with 95% CI for the incidence of a CHD event and CHD death were calculated by using Cox proportional hazard regression. The squares and horizontal lines represent the study-specific HRs and 95% CI, respectively. The area of the squares reflects the study-specific weight. The “total square” represents the pooled HRs and 95% CI. ARIC, Atherosclerosis risk in Communities Study; ATBC, Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study; FMC, Finnish Mobile Clinic Health Examination Survey; HPFS, Health Professionals Follow-up Study; IWHS, Iowa Women's Health Study; NHSb, Nurses' Health Study; VIP, Västerbotten Intervention Program; WHS, Women's Health Study.

Figure 3

Risk of coronary (CHD) event associated with each 1 g/d of alpha-linolenic acid (ALA) intake, among men and women with a long-chain n-3 fatty acid (n-3 LCPUFA) intake below (black circle) or above (white triangle) the median intake (women: 0.15 g/d; men: 0.26 g/d). Data are given as hazard ratios (HR) by using Cox proportional hazards regression and error bars indicate 95% confidence intervals (CI). The model was adjusted for age at baseline and the calendar year in which the baseline questionnaire was returned, smoking habits, body mass index, physical activity, educational level, history of hypertension, alcohol intake, total energy intake, fibre intake, monounsaturated fatty acid, trans fatty acid, saturated fatty acid, linoleic acid intake.