Key Findings:
Research published after 2008 on dietary ALA intake, ALA tissue levels, and cardiovascular health in humans was assessed. The studies consistently showed an increase in blood ALA levels after ALA supplementation, starting at low doses (<2 g/d). ALA supplementation also increased blood levels of EPA, but not of DHA, indicating conversion of ALA to EPA through elongation and desaturation. Short-term trials (6–12 weeks) in generally healthy individuals mostly showed no or inconsistent effects of ALA intake (1.2–3.6 g/d) on blood lipids, LDL oxidation, lipoprotein (a), and apolipoproteins A-I and B. There is observational evidence that a high ALA status may be related to a lower risk of metabolic syndrome. Long-term treatment with high ALA doses had a beneficial effect on body weight and blood LDL cholesterol, which warrants confirmation in future trials. Recent data provide support that ALA could protect against atherosclerosis.
ABSTRACT:
There is a large body of scientific evidence that has been confirmed in randomized controlled trials indicating a cardioprotective effect for omega-3 fatty acids from fish. For alpha-linolenic acid (ALA), which is the omega-3 fatty acid from plants, the relation to cardiovascular health is less clear. We reviewed the recent literature on dietary ALA intake, ALA tissue concentrations, and cardiovascular health in humans. Short-term trials (6–12 weeks) in generally healthy participants mostly showed no or inconsistent effects of ALA intake (1.2–3.6 g/d) on blood lipids, low-density lipoprotein oxidation, lipoprotein (a), and apolipoproteins A-I and B. Studies of ALA in relation to inflammatory markers and glucose metabolism yielded conflicting results. With regard to clinical cardiovascular outcomes, there is observational evidence for a protective effect against nonfatal myocardial infarction. However, no protective associations were observed between ALA status and risk of heart failure, atrial fibrillation, and sudden death. Findings from long-term trials of ALA supplementation are awaited to answer the question whether food-based or higher doses of ALA could be important for cardiovascular health in cardiac patients and the general population. (Author’s abstract)
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