Flashback Friday: Flaxseeds for Hypertension

A recent article in the journal Meat Science acknowledged that “a sector of the population perceives meat as a food that is detrimental to their health” because of studies associating meat consumption with heart disease and cancer. “For these reasons, these meat consumers look for healthier food alternatives as a means to maintain good health;” so, this represents a good opportunity for the industry to develop some new products. Natural foods could be added to meat to reach those health-oriented consumers by boosting antioxidant levels, for example. Foods like flax seeds and tomatoes are healthy, associated with reduced risks of cancer and cardiovascular disease. So, by making flax seed-tomato burgers, they figure they can reduce saturated fat intake and maybe eat less sugar somehow? It’s like their flax seed-fed pork idea, to produce “enriched lard.” Wouldn’t it be easier to just cut out the middle-pig and eat flax seeds ourselves?

Flax seeds have been described as a “miraculous defense against some critical maladies.” I’m a fan of flax, but this title seemed a bit over exuberant; I figured something just got lost in translation. But then, I saw this study, and realized maybe that title was not too far off.

Rarely do we see a dietary study of this caliber. A prospective, double-blinded, placebo-controlled, randomized trial—you know how hard that is in a nutrition study? For drugs it’s easy, you have two identical looking pills: one’s active, one’s placebo, and until the end of the study neither the researcher nor the patient has any idea which is which, hence, double blind. But people tend to notice what they’re eating. So, how did they sneak a quarter cup of ground flax seeds into half of the people’s diets without them knowing? They created all these various flax- or placebo-containing foods, and even added bran and molasses to match the color and texture; so, it was all a big secret–until six months later, when they broke the code to see who ate which.

Why test it on hypertension? Because having a systolic blood pressure over 115—that’s the top number—may be the single most important determinant for death in the world today. If you take a bunch of older folks, most of them on an array of blood pressure pills and don’t improve their diet at all, despite the drugs, they may start out, on average, hypertensive and stay hypertensive six months later. But those who were unknowingly eating ground flax seeds every day dropped their systolic blood pressure about ten points, and their diastolic, the lower number, by about seven points. That might not sound like a lot, but a drop like that could cut stroke risk 46%, heart disease 29%, and that ten-point drop in the top number could have a similar effect on strokes and heart attacks. And for those who started out over 140, they got a 15-point drop. “In summary, flaxseed induced one of the most potent antihypertensive effects ever achieved by a dietary intervention.” In other words, the magnitude of this decrease in blood pressure demonstrated by dietary flax seeds, is as good or better than any other nutritional interventions, and comparable to many drugs, which can have serious side effects. And they’re not exaggerating about the comparable to drugs bit. The flax seeds dropped systolic and diastolic up to 15 and 7. Compare that to powerful ACE inhibitors, like Vasotec, which may drop pressures only 5 and 2. Calcium channel blockers, like Norvasc or Cardizem, 8 and 3–half of what the flax can do. Side effects include… Compare this list to the side effect of flax seeds–its pleasant nutty flavor.

During the six-month trial, there were strokes and heart attacks in both groups. Even if the flax seeds can cut risk in half, though, any avoidable risk is unacceptable. Isn’t high blood pressure just inevitable as we get older? No. The prevalence of hypertension does increase dramatically with age, but not for everyone. People who eat more plant-based diets or keep their salt intake low enough tend not to exhibit any change in blood pressure with advancing age. So, flax is great, but always better to prevent the disease in the first place.

To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Katie Schloer.

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• S Czernichow, A Zanchetti, F Tumbull, F Barzi, T Ninomiya, A P Kengne, H J Lambers Heerspink, V Perkovic, R Huxley, H Arima, A Patel, J Chalmers, M Woodward, S Macmahon, B Neal, Blood Pressure Lowering Treatment Trialists Collaboration. The effects of blood pressure reduction and of different blood pressure-lowering regimens on major cardiovascular events according to baseline blood pressure: meta-analysis of randomized trials. J Hypertens. 2011 Jan;29(1):4-16.
• Norvasc (amlodipine besylate) tablets label. Food and Drug Administration.
• T D Turner, C Mapiye, J L Aalhus, A D Beaulieu, J F Patience, R T Zilstra, M E Dugan. Flaxseed fed pork: n-3 fatty acid enrichment and contribution to dietary recommendations. Meat Sci. 2014 Jan;96(1):541-7.
• M Valenzuela Melendres, J P Camou, N G Torrentera Olivera , E Alvarez Almora, D Gonzalez Mendoza, L Avendano Reyes. Response surface methodology for predicting quality characteristics of beef patties added with flaxseed and tomato paste.
• S Akhtar, T Ismail, M Riaz. Flaxseed - a miraculous defense against some critical maladies. Pak J Pharm Sci. 2013 Jan;26(1):199-208.
• D Rodriguez-Leyva, W Weighell, A L Edel, R Lavallee, E Dibroy, R Pinneker, T G Maddaford, B Ramjiawan, M Aliani, R Guzman, G N Pierce. Potent Antihypertensive Action of Dietary Flaxseed in Hypertensive Patients. Hypertension. 2013 Dec;62(6):1081-9.

Images thanks to John and Anni Winings via Flickr.