Key Findings:
The research supports the role of ALA in flaxseed in producing hypotensive effects in patients with high blood lipids levels (who are at increased risk of developing hypertension). ALA at a level of 8g/d (one tablespoon of flax oil) fed for 12 weeks resulted in a significant reduction of blood pressure of approximately 5mm Hg or 3–6% and was also significantly different from the control, LA-enriched diet. The hypotensive effect produced by ALA was found to be clinically relevant, and could contribute to the reductions on CVD risk found in people who consume flaxseed and flax oil.
ABSTRACT:
OBJECTIVE: Alpha-linolenic acid (ALA) is the natural precursor of the cardioprotective long-chain n-3 fatty acids. Available data indicate a possible beneficial effect of ALA on cardiovascular disease (CVD), but the response of various CVD risk factors to increased ALA intake is not well characterized. The purpose of the present study was to examine the effect of increased ALA intake on blood pressure in man. DESIGN, SETTING, SUBJECTS AND INTERVENTIONS: We used a prospective, two-group, parallel-arm design to examine the effect of a 12-week dietary supplementation with flaxseed oil, rich in ALA (8 g/day), on blood pressure in middle-aged dyslipidaemic men (n=59). The diet of the control group was supplemented with safflower oil, containing the equivalent n-6 fatty acid (11 g/day linoleic acid (LA); n=28). Arterial blood pressure was measured at the beginning and at the end of the dietary intervention period. RESULTS: Supplementation with ALA resulted in significantly lower systolic and diastolic blood pressure levels compared with LA (P=0.016 and P=0.011, respectively, from analysis of variance (ANOVA) for repeated measures). CONCLUSIONS: We observed a hypotensive effect of ALA, which may constitute another mechanism accounting in part for the apparent cardioprotective effect of this n-3 fatty acid. (Authors Abstract)