Objective: The objective was to examine the association between alpha-linolenic acid (ALA, 18:3n-3) intake and risk of ischemic heart disease (IHD) in healthy subjects and to see if this was modified by intake of n-3 LC-PUFA or linoleic acid (LA, 18:2n-6).
Experimental Design: This was a prospective cohort study of 3277 healthy Danish women and men free of known IHD.
Results: Four hundred seventy-one cases of IHD were observed during a median follow up period of 23.3 y. Higher intake of ALA was not significantly associated with decreased risk of IHD among women or men. Although the HR of IHD was stepwise decreased with increasing ALA intake in men [0.84 (95% CI: 0.62, 1.14) in the medium compared with the lowest tertile (reference) and 0.83 (95% CI: 0.56, 1.24) in the highest compared with the lowest tertile], this change was far from significant (P-trend: 0.39). No evidence of effect modification by n-3 LC-PUFA or LA was observed. High n-3 LC-PUFA intake, in comparison with low intake, was inversely associated with risk of IHD; this trend was significant in women (P = 0.04; HR: 0.62; 95% CI: 0.40, 0.97) but not in men (P = 0.15; HR: 0.74; 95% CI: 0.51, 1.06). No associations were observed between intake of LA and risk of IHD.
Authors’ Conclusion: This study suggests that there is no association between ALA intake and risk of IHD, but a high intake of n-3 LCPUFA had a significant cardioprotective effect in women.
Omega-3 Heart Health Benefit Questioned
Vedtofte MS Jakobsen MU Lauritzen L and Heitmann BL (published ahead of print Aug 24, 2011). Dietary alpha–linolenic acid, linoleic acid, and n-3 long-chain PUFA and risk of ischemic heart disease. Am J Clin Nutr doi: 10.3945/ajcn.111.018762.
What You Need To Know
The headline “Study Clouds Picture on Omega-3s and Heart Health” carried by the news media couldn’t be further from the truth. Beginning with the seminal investigations of Bang and Dyerberg (1980), there now exists data in both sexes across a wide range of ages demonstrating the utility of the long-chain omega-3s in primary prevention of cardiovascular events. In addition, the already substantial list of long-chain omega-3 recommendations from professional organizations and government bodies continues to grow because the science is so compelling.
What Else Should You Know?
In an ecological study conducted by Zhang et al. (1999), fish consumption was associated with a reduced risk from all-cause, ischemic heart disease and stroke mortality across 36 countries. Why wasn’t this study mentioned in the current publication?
In a case-control study nested in the Cardiovascular Health Study, Lemaitre et al. (2003) found a highly significant relationship between serum phospholipid n-3 LC-PUFA concentrations and risk of fatal ischemic heart disease. A one standard deviation increase above the mean serum phospholipid EPA+DHA concentration (3.3% to 4.1% of total fatty acids) was associated with a 68% reduction in the relative risk of fatal ischemic heart disease. Why wasn’t this study mentioned in the current publication?
Note that the authors’ conclusion “This study suggests that there is no association between ALA intake and risk of IHD, but a high intake of n-3 LCPUFA had a significant cardioprotective effect in women” is not in-line with the media’s portrayal of the study outcome.
Global Organization for EPA and DHA Omega-3s (2011). Omega-3 Heart Health Benefit Questioned [Peer commentary on the paper “Dietary alpha–linolenic acid, linoleic acid, and n-3 long-chain PUFA and risk of ischemic heart disease” by Vedtofte MS Jakobsen MU Lauritzen L and Heitmann BL (published ahead of print Aug 24, 2011). Am J Clin Nutr doi: 10.3945/ajcn.111.018762].
Bang HO and Dyerberg J. Lipid metabolism and ischemic heart disease in Greenland Eskimos. In: Draper H (ed.) Advances in Nutrition Research Volume 3. New York: Plenum Press, 1980:1–22.
Lemaitre RN King IB Mozaffarian D Kuller LH Tracy RP Siscovick DS (2003). n-3 polyunsaturated fatty acids, fatal ischemic heart disease, and nonfatal myocardial infarction in older adults: the Cardiovascular Health Study. Am J Clin Nutr 77:319–325.
Zhang J Sasaki S Amano K Kesteloot H (1999). Fish consumption and mortality from all causes, ischemic heart disease, and stroke: an ecological study. Prev Med 28:520-529.