In the News: Omega-3s & Blood Pressure; AREDS2 CVD Study Results

Hypertension Common in U.S.

According to the National Heart, Lung and Blood Institute (NHLBI), about 1 in 3 adults in the U.S. have hypertension. While the condition usually has no outward signs or symptoms, cardiac, vessel and renal damage can occur over time if left untreated. There is also increasing evidence to suggest that patients with systemic risk factors such as hyper-tension are at higher risk of AMD (1).

Meta-analysis: Omega-3 Fats & Blood Pressure

A meta-analysis (2) published online ahead of print in the American Journal of Hypertension suggests that consuming omega-3 supplements or omega-3 rich foods may be as effective as some lifestyle changes for reducing elevated blood pressure.

The meta-analysis, which included data from 70 randomized controlled trials (RCTs) that were greater than 3 weeks in duration, reports advantages for both normo- and hypertensives, with the greatest benefits seen in those with untreated high blood pressure.

The strongest effects of eicosapentaenoic and docosahexaenoic acids (EPA+DHA) were observed among untreated hypertensive subjects. The average reductions in systolic and diastolic pressures were 4.51 mm Hg and 3.05 mm Hg, respectively. For  perspective, studies in untreated hypertension show that reducing sodium decreases systolic pressure by 2-8 mm Hg, alcohol by 2-4 mm Hg, and that physical activity reduces systolic values by 4-9 mm Hg.

Blood pressure was also lowered among normo-tensive subjects (systolic pressure = - 1.25mm Hg; diastolic pressure = - 0.62mm Hg). Noting that blood pressure tends to rise with age, the NHLBI states that a healthy lifestyle can help some people delay or prevent this rise. The results of this meta-analysis suggest that consumption of omega-3 fats might help pre-hypertensives from becoming hypertensives. 

The study’s authors conclude that, overall, available evidence from RCTs indicates that ≥2 g of EPA+ DHA per day reduces systolic and diastolic pressures. Lower doses (between 1-2 g daily) may reduce systolic, though not diastolic pressure.

AREDS2 Cardiovascular Outcome Study

Results from the Cardiovascular Outcome Study (COS), an ancillary study of the Age-Related Eye Disease Study 2 (AREDS2), were published online ahead of print this month (3). The purpose of COS was to determine whether supplemental omega-3 fatty acids (EPA+ DHA) or lutein+ zeaxanthin taken along with AREDS nutrients reduce the rate of cardiovascular disease (CVD) in elderly participants with AMD.

Neither supplementation of omega-3 fatty acids nor lutein+ zeaxanthin reduced the risk of CVD events or CVD mortality. (Although a 25% reduction in CVD events was required to achieve statistical significance, an accompanying editorial opined that a reduction of 10-15% would have been “more prudent and realistic.”)

Despite the overall null results, pre-specified subgroup analyses suggest potential benefits for certain healthy people – specifically, those with no history of CVD or at low risk of developing the disease.

A significant 34% reduction in CVD risk was observed in those with no baseline history of hypertension.  Similar, though non-significant, trends of 19% and 18% reductions in risk were seen for participants with no history of CVD and no history of elevated cholesterol, respectively. The omega-3 supplements were also well tolerated with no adverse effects noted.

These observed protective effects support the notion that regular intake of omega-3 fatty acids may help reduce the risk of CVD among healthy populations.

References

1. Cheung CM, et al. Review. Is age-related macular degeneration a manifestation of systemic disease? J Intern Med. [Epub ahead of print] Mar, 2014. 
2. Miller PE, et al. Long-chain omega-3 fatty acids EPA and DH and blood pressure: A meta-analysis of randomized controlled trials. Am J Hyperten [Epub ahead of print] Mar, 2014.
3. AREDS2 Writing Group. Effect of long-chain ω-3 fatty acids and lutein+zeaxanthin supplements on cardiovascular outcomes. JAMA. Inter Med. [Published online] Mar, 2014.