Despite the prevalence of hypertension (high blood pressure), a cure still eludes medical researchers. Hypertension medication can be lifesaving, but it does not correct the underlying cause of the disorder. Indeed, for most cases of hypertension the cause is not known. At one time, it was thought that a rise in blood pressure was a normal and necessary part of the ageing process, which is why hypertension not caused by some other underlying disease was called essential hypertension. Increased blood pressure was thought to be essential to maintain adequate circulation in older adults.

But blood pressure does not increase with age in many other cultures, especially in nonindustrialised countries. Yet 50% of all Americans have hypertension by age 74. What is it about the western way of life that makes us so prone to hypertension? Can an understanding of the relationship between life-style and the development of hypertension help us prevent this disorder?

Hypertension appears to have both genetic and environmental causes. Many risk factors for the development of hypertension have been identified. Unmodifiable risk factors include:

• family history of hypertension (people whose parents or siblings developed hypertension are at increased risk)
• age (risk increases with age)
• ethnicity (black Americans have greater risk)
• gender (men have more hypertension between the ages of 18 and 54, and women have more hypertension after age 65).

People who fall into a high-risk group should not worry. (Worrying will only increase your blood pressure.) A wellness life-style can significantly reduce a person's risk of developing hypertension and decrease its severity should it develop. Life-style change is particularly effective in helping to lower blood pressure for those with borderline or mild hypertension, 80% of hypertensives.

A healthful diet can help prevent hypertension. Almost everyone has heard that minimising sodium intake is important. Sodium sensitivity often develops with age, so even though excess sodium does not currently raise your blood pressure, it may in the future. Anyone at risk for hypertension, and indeed anyone planning to grow old, may benefit from not acquiring a taste for salty food. Animal studies also suggest that salty diets may damage arteries even without causing an increase in blood pressure. In one study, rats fed high-salt diets experienced only a slight rise in blood pressure, but all died much earlier than littermates on a low salt diet. Autopsies revealed a great deal of arterial damage, including atherosclerosis, and associated damage to brain cells supplied by the damaged arteries. Epidemiological studies support the dangers of a high-salt diet as well. For example, people who live in northern Japan consume high-salt diets and also have a very high incidence of stroke.

Some studies have found that an increased intake of calcium and potassium helps lower blood pressure. Calcium is found in dairy products, dark green vegetables, and calcium enriched products such as some brands of orange juice and soy milk. Potassium is found in many fruits and vegetables.

An adequate intake of magnesium may also help regulate blood pressure. In animal studies, magnesium deficiency increases vascular muscle tone, thus increasing peripheral resistance to blood flow. Magnesium is found in legumes, nuts, whole grains, and meat.

Alcohol consumption has been strongly associated with hypertension: The greater the alcohol intake, the greater one's risk of hypertension. Many people find that their blood pressure improves when they decrease their alcohol consumption. Caffeine is a stimulant and increases blood pressure, so consumption should be limited if one has or is at risk for developing hypertension.

People who are more than 20% above their desirable weight have twice as much hypertension. Extra fat in the abdominal region is more strongly associated with hypertension than excess fat in the hips and thighs. A small weight loss can significantly decrease blood pressure, even if the person does not lose all of the extra weight.

Abdominal obesity is also associated with insulin resistance. People with insulin resistance produce enough insulin, but the insulin receptors located in the cell membrane are not sensitive enough to respond correctly, and blood insulin levels rise. Insulin stimulates sympathetic nervous system activity, similar to the stress response that causes blood pressure to rise. Insulin may also lead to fluid retention, which increases blood pressure. Weight loss often helps restore insulin sensitivity.

Nicotine is a potent vasoconstrictor, so here's one more reason not to smoke. When a cigarette is smoked, nicotine enters the blood immediately, and vasoconstriction occurs systemically. The more nicotine and the more frequently one smokes, the greater the vasoconstriction. Smokers usually have chronically elevated blood nicotine levels and increased vascular resistance.

Many studies have found that regular aerobic exercise can normalise blood pressure in People with borderline hypertension. Epidemiological studies have also found that exercise can improve the health of people with this condition. In fact, one study showed that hypertensives who exercised regularly had almost the same mortality rates as people with normal blood pressure.

Exercise may exert this protective effect partly by contributing to a person's weight control efforts. Regular aerobic exercise may also lead to decreased vascular resistance, perhaps by increasing parasympathetic output (the relaxation response) when the person is at rest.

Insulin sensitivity improves for many hours after exercise. As mentioned above, this could prevent the sympathetic nervous system activity and fluid retention that could contribute to high blood pressure.

Many people find that exercise helps them relax and decreases their stress reactivity. Things don't upset them as easily. Several studies have demonstrated an association between stress and hypertension, so exercise may be helpful because it reduces a person's stress response.

It has been hypothesised that chronic stress may lead to a chronic elevation in sympathetic nervous system activity. This includes an elevation in the hormones associated with the stress response, including epinephrine and norepinephrine, which might cause chronic high blood pressure. Stress management techniques can help a person learn relaxation skills that decrease sympathetic output and thus reduce blood pressure.