Understanding and Overcoming high blood pressure

How to use food to regulate hypertension

There are a number of changes you can make to your diet to help regulate your blood pressure (BP). Maintaining a sufficient amount of dietary fiber is paramount in regulating blood pressure. A 2005 meta-analysis of 25 trials found that soluble or insoluble fiber intake resulted in a reduction of around 1 mm Hg in systolic or diastolic BP. More recently, in a high-quality trial it was shown that adding 30 g/day milled flaxseed to the diets of 110 patients with peripheral arterial disease resulted in relatively large drops in BP of 10 mm Hg systolic and 7 mm Hg diastolic after 6 months.3 These impressive results may have been the result of both the fixed oil in the milled flax contributing to the hypotensive effect, as well as the fiber. Alpha-linolenic acid (found in flaxseed oil) has been shown to reduce BP in clinical studies, albeit at relatively high doses.4

Blood Pressure

Beets (red beet, Beta vulgaris) are probably the richest dietary source of nitrate. After ingestion, the nitrate in beets (best taken as the raw juice or baked, as other methods tend to leach the nitrate out) acts as a reservoir (via nitrite formation) for the production of the local microvascular hormone nitric oxide. In the blood vessel wall and red blood cells, nitrite is reduced to nitric oxide and other nitrogen oxides, which leads to vasodilation, maintenance of BP and protection against ischaemia-reperfusion injury.5 In other words, BP is lowered and tissue nutrition is improved.

A number of herbs are used traditionally to help lower BP. They’re not supported by modern clinical evidence, but often work well in practice. Valerian is one example. Whether this herb acts as a peripheral or central vasodilator, or if the activity is due to a general calming effect on the nervous system, is not known. It is usually prescribed for stressed patients.1 Cramp bark, as the name suggests, relaxes smooth muscle. For dandelion, the leaves have diuretic activity and high levels of potassium and can be useful especially for the in the elderly.2 Antioxidant herbs, such as grape seed, turmeric and pine bark, could also be of value and will help to address other cardiovascular risk factors.

Beets substantially lowered blood pressure!

Clinical trials have established the benefit of beet juice in lowering BP. For example, the results of a randomized, controlled, single blind, crossover trial investigating the effect of beet juice (study 1) and beet-enriched bread (study 2) on BP in healthy men were published in 2012. In both studies, the baseline BP was within the normal range: an average of about 130 mm Hg for systolic BP, and 80 mm Hg for diastolic BP. Participants also consumed a low-nitrate and low-nitrite diet one day prior, and did not take any vitamin or mineral supplements. Ambulatory BP was measured over a 24-hour period following consumption of beet or controls. The beets substantially lowered blood pressure. For example, the juice resulted in a 13.1 mm Hg reduction in systolic BP and a 16.6 mg Hg reduction in diastolic BP.

Total urinary nitrate/nitrite concentrations were measured as an indicator of systemic nitric oxide production. Concentrations increased in accordance with the reductions in BP after consumption of beet juice and bread.18 Subsequently a  meta-analysis was conducted of 16 placebo controlled clinical trials investigating the effect of inorganic nitrate or beet juice on BP.6  Treatment was associated with reductions in systolic (4.4 mm Hg) and diastolic (1.1 mm Hg) BPs. This effect of nitric oxide production from dietary nitrate can be accentuated by sunlight exposure.7

Flavanol-rich chocolate is a BP super food

Much maligned as an unhealthy indulgence, chocolate or cocoa (Theobroma cacao) taken in certain forms (with low sugar particularly) is emerging as a new super food. One of its benefits is the lowering of BP, and there is high-level evidence to support this. In 2012, members of the Cochrane Collaboration published their systematic review and meta-analysis of the impact of cocoa on BP.8 Twenty studies met the inclusion criteria. Meta-analyses of the 20 studies involving 856 mainly healthy participants revealed a statistically significant BP-reducing effect of flavanol-rich cocoa products in short-term trials of 2 to 18 weeks’ duration. The mean reduction in systolic BP was 2.77 mm Hg (p=0.005) and the mean drop in diastolic BP was 2.20 mm Hg (p = 0.006). Trials provided participants with 30 to 1080 mg of flavanols (mean 545.5 mg) in 3.6 to 105 g of cocoa products per day. In half of the trials, the active group consumed 500 to 750 mg of flavanols per day. The easiest way to consume clinically relevant quantities of flavanol-rich cocoa is via 85% chocolate, at around 20 to 40 g per day.

Turn to tea to lower BP

Herbal teas (other than green or black tea above) are also a relevant addition to the treatment mosaic for BP. One of the best-studied teas in this regard is from Hibiscus sabdariffa, sometimes known as roselle or rosella, but also called sour tea. A good quality US study published in 2010 examined the hypotensive activity of a Hibiscus tisane using a randomized, double blind, placebo-controlled trial.9 Sixty-five pre- or mildly hypertensive adults not taking BP-lowering drugs drank either three 240 mL servings of brewed Hibiscus tea or a placebo tea for 6 weeks. By the end of the trial, systolic BP was lowered by an average of 7.2 ± 11.4 mm Hg. While diastolic BP was lower, this was not different to placebo. Participants with a higher systolic BP at baseline showed a greater response to the Hibiscus tea. Other clinical trials on Hibiscus have also found a lowering of BP, but were of poorer quality.10

A dash of salt?

The DASH (Dietary Approach to Prevent Hypertension) protocol is high in fruit, vegetables, whole grains, low-fat dairy products, fish, chicken and lean meats.11 In one trial, DASH lowered systolic/diastolic BP by 6.9/3.7 mm Hg.

Sodium reduction is controversial, but only in that severe restriction can have adverse effects.12

The recent Cochrane Collaboration review and meta-analysis considered this, concluding that a modest salt reduction (about 4 g/day) causes a significant fall in BP (4.18 mm Hg for systolic).13

A complete hypertension intervention

Given the mosaic nature of hypertension a truly rational treatment approach will:

  • Be broad-based to cover the multiple factors
  • Combine treatments that add together to give the needed reduction in BP
  • Protect the vascular endothelium and microcirculation
  • involve diet, herbs (as previously discussed) and supplements (especially magnesium and vitamin C, which are supported by high-level clinical evidence), and lifestyle modification

In terms of diet, this 8-point dietary plan is recommended:

•  The key elements of the DASH guidelines

•  As part of this, berries and other fruit and vegetable juices

•  Cocoa (say 85% chocolate, 20 g/day, about 2/3 oz)

•  Green tea and hibiscus tea – several cups per day of each

•  Garlic as 1 to 2 fresh, crushed raw cloves/day

•  Beet as juice or supplement (at least 10 oz of juice per day)

•  Fiber, especially 30g/day (1 oz) of freshly milled flaxseeds

•  Reduce salt to 3 g/day

Lifestyle modification is important, particularly focusing on exercise, weight loss (especially fat around the belly), stress reduction, adequate sleep and moderate alcohol intake.

It’s hard work and requires focus, but the health benefits will extend well beyond just lowering BP. Not many people want to take drug medications all their life?

In summary, most of the dietary, lifestyle or herbal interventions noted above will only likely have a small effect on BP, of the order of a few mm Hg. But given that hypertension is a mosaic disease, and each intervention is more than likely to address a different piece in the mosaic, it is reasonable to assume that their effects will be additive. Hence, 10 measures (dietary, lifestyle and supplements) that each reduce systolic BP by say 2.5 mm Hg will result in a total reduction of around 25 mm Hg, a clinically significant outcome. In other words, hypertension is a mosaic disease that can be effectively managed by a well-targeted complex intervention.

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