Impressive Antihypertensive Effect With Flaxseed

November 06, 2012

LOS ANGELES — Adding flaxseed to the diets of patients with peripheral arterial disease (PAD) resulted in large drops in blood pressure (BP) of around 10 mm Hg systolic and 7 mm Hg diastolic after six months, according to the results of a double-blind, placebo-controlled study.

"This reduction of SBP and DBP after administration of dietary flaxseed is the largest decrease in BP ever shown by any dietary intervention," said Dr Delfin Rodriguez (University Hospital Holguin, Cuba) speaking here today at the American Heart Association 2012 Scientific Sessions. Such reductions would be expected to result in around a 50% fall in the incidence of stroke and a 30% reduction in MI, he added.

This reduction of SBP and DBP after administration of dietary flaxseed is the largest decrease in BP ever shown by any dietary intervention.

Rodriguez explained that the trial, FLAX-PAD, was conducted in PAD patients because they happened to have a clinic for the disease in their center and, as around 75% of PAD patients have concomitant hypertension, "it was an easy population to study."

Subgroup analyses of only the PAD patients with hypertension showed a greater reduction in SBP, of about 15 mm Hg, in these patients than in the study population as a whole and a similar reduction in DBP, he noted.

"Flaxseed represents a particularly attractive strategy for controlling hypertension in economically disadvantaged communities and countries, and its BP-lowering effects compare favorably with those of antihypertensive drugs and lifestyle modifications, such as a low-salt diet and weight loss," he noted.

Flaxseed Is Antiatherogenic, Anti-Inflammatory, and Antiarrhythmic

Rodriguez said that he and his colleagues chose to study flaxseed because animal studies have shown it has antiatherogenic, anti-inflammatory, and antiarrhythmic effects and may reduce circulating cholesterol and trans-fatty acid levels.

They randomized 110 patients with PAD and an ankle-brachial index (ABI) <0.9 to milled flaxseed (30 g/day) in the form of bagels, muffins, and buns (n=58) or placebo products (n=52), made from wheat with a similar flavor, for one year.

Baseline characteristics were similar between the two groups, with hypertension being highly prevalent--around three-quarters of the PAD patients had high blood pressure, and 80% were taking antihypertensive medications. BP measurements were based on an average of three readings taken in the sitting position with a mercury sphygmomanometer by a trained nurse.

Rodriguez reported six-month results. "We obtained an important decrease in SBP and DBP using flaxseed compared with placebo," he observed, noting that the reductions were statistically significant (p=0.04 for SBP and p=0.004 for DBP). SBP in the placebo group increased by ~3 mm Hg and DBP remained the same over the six-month period.

He added that the results out to one year are in the process of being analyzed and will be presented at a future date. This includes trying to figure out which particular constituents of flaxseed may be responsible for the antihypertensive effects, he noted. The flaxseed group exhibited a twofold increase in plasma alpha-linolenic acid and a 10-fold increase in enterolactone levels (p=0.003), but levels of these compounds did not change in the placebo group.

"Flaxseed has different components, including alpha-linolenic acid, enterolignans, and fiber, and all have been shown to decrease BP. We think we are seeing a synergistic effect of different compounds," he commented.

The authors reported no conflicts of interest.