Flaxseed is emerging as one of the most effective nutritional medicines for lowering blood pressure.
In a study known as FlaxPAD, which involved 110 people with peripheral arterial disease, eating 30g of ground flaxseed per day, for 6 months, was associated with significant blood pressure reductions of 10/7 mm Hg blood pressure compared with placebo. In those with hypertension at the start of the trial (systolic blood pressure 140 mmHg or above) blood pressure improvements were even greater at 15/7 mmHg in those taking flaxseed. These results are astonishing, given that participants had significant hardening and furring up of the arteries, and the researchers concluded that flaxseed ‘induced one of the most potent antihypertensive effects achieved by a dietary intervention’.
Another recent study showed that flaxseed can also lower central blood pressure in the aorta – the largest artery in the body. In patients with high blood pressure, the average decrease in central blood pressures was 10/6 mm Hg compared with placebo.
When data from 14 earlier trials, involving 1004 people, were analysed, the overall result showed that flaxseed supplements reduced blood pressure by an average of 1.77/1.58 mm Hg. This seems a lot less dramatic, although a 2 mm Hg reduction in systolic blood pressure can lower the risk of stroke mortality by 10% and the mortality from ischemic heart disease by 7%.
However, not all these studies did used all the components of flaxseed. Six used flaxseed oil and 3 used flaxseed extracts containing concentrated lignans in capsule form, rather than ground or whole flaxseed which are recognised as producing the most pronounced reductions in blood pressure. Another consideration is that some studies only lasted 3, 4 or 6 weeks, and trials of longer durations, of at least 12 weeks, were shown to have the best response.
How does flaxseed lower blood pressure?
Flaxseeds are a rich source of the short-chain omega-3 fatty acid, alpha-linolenic acid, fibre, oestrogen-like plant hormones (lignans) and other antioxidant polyphenols. These have a variety of beneficial effects on the circulation, especially relating to cholesterol and glucose control, but the main antihypertensive effect of flaxseed is now thought to result from the high levels of alpha-linolenic acid. This omega-3 was found to block an enzyme called epoxide hydrolase which would otherwise generate substances known as oxylipins which are associated with a rise in blood pressure.
How to add flaxseed to your diet
Although flaxseed oil supplements are widely available, you will gain the best blood pressure lowering effect by eating ground or whole flaxseeds. Milling releases significantly more omega-3 and lignans for absorption than when eating the seeds whole.
Sprinkle the flaxseed on any meal, add to muesli, smoothies, deserts, and use in baking, too. Regular daily use of 30g was the dose used in clinical trials, with best results seen after 12 weeks.
|Linwoods Organic, Milled Flaxseed provides 5.8g omega-3 per 30g serving.
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A similar product in the US is Spectrum Organic Ground Flaxseed.
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|If you prefer to grind your own linseed (use a coffee grinder) for maximum freshness, whole seeds are also available.
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If you have high blood pressure, then following the so-called DASH diet – which is essentially a low-salt version of the Mediterranean diet, will also produce good results.
Image credits: HealthAliciousness.com/flickr;