Medical Edge Newspaper Column

Controlling High Blood Pressure: What Works and What Doesn't

Jan. 21, 2007
Dear Mayo Clinic:
I'm taking L-arginine and L-citrulline because I read that they will normalize blood pressure and reduce the risk of strokes. Is this true? -- Glen Cove, N.Y.

Answer:
It's very good that you are paying attention to high blood pressure, which doctors consider the leading treatable risk factor for cardiovascular disease and stroke. But there are well-proven treatments and unproven treatments, and you are currently pursuing the latter.

In theory, using L-arginine and L-citrulline would seem to make sense, given that a major cause of high blood pressure in most people is a stiffening of the arteries. Nitric oxide helps to counteract this stiffening, and the amino acid L-arginine is a source of nitric oxide. L-citrulline, another amino acid, is in turn a source of L-arginine.

One might think that flooding the system with these two chemicals, which are widely available in supplement form, would reduce blood pressure and the subsequent risk of stroke. Unfortunately, there is no evidence that either of these outcomes actually occurs in humans.

Moreover, the indiscriminate use of supplements can cause problems of their own. For one thing, there is the issue of quality. Because they are not officially considered drugs, supplements are not regulated by the U.S. Food and Drug Administration, so you don't know what is actually contained in the product you've purchased. For another, because these supplements haven't been shown to reduce high blood pressure, their use as a substitute for proven treatments can be harmful.

Blood pressure is determined by the amount of blood your heart pumps and the degree of resistance to blood flow in your arteries, which normally are flexible. Arteries that stiffen offer greater resistance to blood flow and produce higher blood pressure. The resulting damage to blood vessels over time can result in deposits of fat in the artery wall (atherosclerosis) or an enlarged, bulging blood vessel (aneurysm) caused by weakened tissue. These conditions can lead to stroke -- an interruption of blood flow to part of the brain or bleeding into the brain -- which can cause serious damage and loss of brain function.

The best "treatment" for high blood pressure is to prevent it from happening in the first place. And while we cannot alter certain risk factors such as age, race, gender and family history, others are very much within our control. The three most important "lifestyle" changes you can make are: keeping your weight down (greater body mass means more blood is needed to maintain your tissues, and the increased flow creates extra force on artery walls); being more physically active (which reduces one's risk of being overweight); and minimizing salt intake (in many people, sodium leads to fluid retention and increased blood pressure). Other desirable lifestyle changes include sufficient potassium intake (to help balance sodium levels), stress reduction, not smoking and avoiding excessive consumption of alcohol.

Sometimes, lifestyle changes alone can't sufficiently lower blood pressure, in which case you may also need medication. The major drug classes include diuretics (which help your body eliminate sodium and water); angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, and calcium channel blockers (which help relax blood vessels); and beta blockers (which cause the heart to beat more slowly and less forcefully). While these and others are proven therapies, there is no one best treatment for everyone. Decisions depend on individual response and medical history.

It is important to discuss with your doctor the roles that both lifestyle changes and medications can play. Maintaining lifestyle changes may improve the effectiveness of the medications you are taking and allow for fewer drugs or lower dosages. Your doctor might also recommend the use of multiple drugs. In fact, low-dose medications in combination can lower blood pressure as well as larger doses of one drug, and with fewer side effects.

-- Stephen C. Textor, M.D., Nephrology and Hypertension, Mayo Clinic, Rochester, Minn.