Research has examined the relationship between omega-3 fatty acids—particularly docosahexaenoic acid (DHA)—and blood pressure using a range of study designs.
A double-blind, placebo-controlled crossover study published in the Journal of Nutrition (2007; 137(4):973–978) evaluated the effects of low-dose DHA supplementation on blood pressure. The study included 38 male participants who were randomized to receive either 700 micrograms of DHA per day or placebo for three months. After a four-month washout period, the groups were crossed over so that participants received the alternate intervention.
During periods of DHA supplementation, average diastolic blood pressure was approximately 3.3 mm Hg lower compared with placebo. Heart rate was also modestly reduced, by an average of 2.1 beats per minute, during DHA supplementation.
Observational data have reported similar associations. A cross-sectional epidemiological study published in Hypertension (2007; 50:313–319) examined dietary intake and blood pressure in 4,680 participants. Blood pressure measurements were obtained eight times across four clinical visits. The investigators reported an inverse relationship between omega-3 fatty acid intake from food sources and blood pressure levels.
Earlier synthesized evidence has also addressed this question. A meta-analysis published in the Archives of Internal Medicine (June 28, 1993; 153:1429–1438) reviewed studies examining fish-oil consumption and blood pressure. Among 11 studies involving individuals with normal blood pressure, omega-3 fatty acid intake was associated with modest reductions in blood pressure. An additional six studies involving individuals with hypertension also reported blood pressure reductions, with the greatest effects observed in participants with higher baseline blood pressure.
Together, these studies describe consistent associations between omega-3 fatty acid intake and modest reductions in blood pressure across controlled trials, population studies, and pooled analyses, with effects varying by dose, baseline blood pressure, and study design.
