Antihypertensives:Keeping blood pressure in check safely

There are literally scores of ways to reduce high blood pressure (BP) without having to take recourse to drugs.

The high incidence of hypertension in the West and its virtual absence in many developing countries is thought to be mainly due to diet. Meat appears to be a major culprit. In a recent Oxford University survey, meat eaters had an average of 4 mmHg higher BP than vegans (Public Health Nutr, 2002; 5: 645-54). The US recently launched a campaign using a diet called DASH (Dietary Approaches to Stop Hypertension) to reduce BP. It is high in fruits, nuts and vegetables, emphasises fish and chicken rather than red meat, and is low in saturated fats and refined carbohydrates. Tested against a diet high in fruit and vegetables, the DASH diet was slightly better, with an average overall BP decrease of 5 mmHg and a staggering 11 mmHg drop in hypertensives (Clin Cardiol, 1999; 22: 6-10).

This result is as good as or even better than what many drugs offer, leading researchers to recommend the DASH diet as a first-line treatment for hypertension (Hypertension, 2001; 38: 155-8). This is yet another example of the medical establishment belatedly accepting what healthfood campaigners have been advocating for decades.

The only controversial aspect of the DASH diet is salt, which has long been thought to play a major role in high blood pressure, though doctors seem to be having a hard time proving it. Some studies show that it causes hypertension, but most don’t (JAMA, 1998; 279: 1383-91). The bottom line is that there is no evidence that reducing either salt or sodium helps people to live longer (Curr Hypertens Rep, 2002; 4: 329-32).

Other minerals, however, are important. People with hypertension are consistently found to be lacking in magnesium, and diets naturally high in magnesium, potassium and calcium are known to reduce BP substantially (Nutr Health Aging, 2001; 5: 144-9). So, should people with hypertension take magnesium supplements? A 20-year-old study believes they should, having discovered that magnesium supplements lowered BP by 12 mmHg (BMJ, 1983; 286: 1847-9). But the latest evidence is not as convincing. Nevertheless, magnesium supplements are recommended for anyone with a magnesium deficiency or who is taking diuretics (Mol Aspects Med, 2003; 24: 107-36).

It is also known that a diet high in sugar impedes potassium uptake, and BP usually decreases when sugar is excluded (J Am Coll Nutr, 1987; 5: 79).

Higher dietary fibre can also lower BP. When more than 30 people switched to a diet of mostly raw high-fibre foods for six months, their diastolic BP plummeted by an impressive 18 mmHg (South Med J, 1985; 78: 841).

But there’s an easier way to achieve nearly the same dramatic reductions – take vitamin C. Dr Balz Frei and colleagues at the Linus Pauling Institute recently tested 45 people with moderate-to-severe hypertension (average 155/87 mmHg) in a double-blind placebo-controlled trial. Patients took either 500 mg/day of vitamin C or a placebo. After a month, BP dropped by 9 per cent with vitamin C, bringing their average BP down to 142/79 mmHg. However, vitamin C did not reduce BP in those whose BP was in the normal range – unlike diuretics, which can reduce BP to dangerously low levels (see lower box, p 2). How does vitamin C do this? ‘We’re not sure of the mechanism,’ says Frei. ‘One theory is that the antioxidant properties of vitamin C protect the body’s level of nitric oxide, a natural compound which relaxes blood vessels and helps maintain a normal, healthy blood pressure’ (Lancet, 1999; 354: 2048-9).

Another possible antihypertensive micronutrient is vitamin B. There’s mounting evidence that homocysteine is a major factor in cardiovascular disease. This naturally occurring amino acid is thought to indirectly cause atherosclerosis (fatty deposits in the arteries) and hypertension. Two key discoveries have been made in the lab: high homocysteine (above 12 mmol/L) is related to low blood levels of vitamin B; and B vitamins can detoxify homocysteine (J Cardiovasc Pharmacol, 2003; 42: 453-61). The recommended dose is vitamin B as folic acid (800 mcg/day) plus B6 and B12 in a daily multivitamin (Am Acad Fam Physicians, 2001; November).

Coenzyme Q10 (CoQ10) is another naturally occurring enzyme with dramatic effects on hypertension. This was first discovered in the 1950s by US nutritionists, who detected this antioxidant deep within body cells and found that it played a vital role in converting nutrients into energy (J Am Chem Soc, 1959; 81: 4007-10). Japanese doctors were the first to take up the new nutrient supplement and found it to greatly benefit heart patients, reporting significant improvements in 75 per cent of cases of congestive heart failure, angina and hypertension (J Molec Med, 1977; 2: 431-60). In 1985, a group of American doctors at the University of Texas began giving CoQ10 to their hypertensive patients. Eight years and more than 400 patients later, they announced their astounding results. A daily dose of 75-600 mg of CoQ10 had improved hypertension to such an extent that, within six months, 97 per cent of these patients could stop taking their conventional drugs (Mol Aspects Med, 1994; 15 [Suppl]: 165-75).

However, it was only recently that the truly extraordinary value of CoQ10 has been acknowledged. Two years ago, US government doctors mounted a full-scale, randomised, placebo-controlled trial where they gave 80 hypertensive patients 60 mg of CoQ10 twice a day for 12 weeks. Systolic BP dropped by 18 mmHg, with no side-effects. ‘CoQ10 may be safely offered to hypertensive patients as an alternative treatment option,’ they concluded (South Med J, 2001; 94: 1112-7). But alternative to what? Certainly not to prescription drugs, which are generally hard put to achieve such a degree of reduction and only with the added penalty of a whole raft of side-effects.

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Written by What Doctors Don't Tell You

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