However you choose to stay active, whether you're walking, going for a run, taking a bike ride, or working in your garden, some new research that says you can increase your energy level with zinc.

According to a recent U.S. Department of Agriculture study, zinc increases performance by helping the body get rid of carbon dioxide, which rises during exercise.

The study involved 14 active men in their 20s and 30s who were placed on a low-zinc diet of just 3.5 mg. a day.

After nine weeks the men in the study were asked to perform two types of exercise tests on a stationary bicycle. During one of the tests -- a 45 minute endurance ride -- four of the men had to stop. Blood tests revealed that they weren't getting the full effects of an enzyme called carbonic anhydrase. This is the enzyme that helps expel carbon dioxide from the body.

After six weeks, the men were given a high-zinc diet along with a 15 mg. zinc supplement and were asked to repeat the exercise tests. Their performance improved dramatically.

Past studies have associated low zinc levels with poor muscle strength, fatigue, and a lack of speed during exercise. So if you want to boost your own performance, try adding more zinc-rich foods, like red meat, oysters, and beans to your diet or consider taking a zinc supplement. Dr. Wright usually recommends 25 to 30 milligrams of zinc (picolinate or citrate). Just make sure to balance it with copper. Long-term zinc use can lead to copper depletion, so if you decide to take it, make sure to take 1 1/2 to 2 milligrams of copper every day too.

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Kava concerns

Q: I have been taking kava to relieve stress, but when I told a friend this she said that it causes liver damage. I have had no problems using it and I was puzzled by her comment. Could it be a problem?

JVW: I think the few problems that have been reported are tainting a long history of safe kava use. Like any product we ingest, moderation is the key.

In a few rare cases liver damage has been attributed to the herb. But there are many experts who feel the case against kava is not proven.

Apparently there are two ways to prepare kava extract, one using the solvent acetone and the other using ethanol. The acetone form is not widely sold in the United States. But in Germany and some other countries, the most popular kava products are made by using acetone as the extracting solvent.

I think the rare cases of liver damage that have been linked to kava stem from allergic reactions, perhaps exaggerated by the solvent used on the plant, and isolated cases of deficiencies in detoxifying enzymes. (In one Swiss case, the kava phytochemicals were believed to have sensitized the patient's immune cells to liver tissue, which they then attacked.)

More research needs to be done to explain the small number of cases where injury to the liver has been associated with kava use. In the meantime, it's a good idea to avoid long-term use of kava unless you are under close, clinical supervision. And avoid using the herb if you have pre-existing liver problems.

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What is...an enzyme?

Enzymes are proteins that act as catalysts for the biochemical processes that make the body run. There are thousands of enzymes, and every cell in the body produces them.

Yours in good health,
Amanda Ross
Editorial Director
Nutrition & Healing

Sources:

"Low dietary zinc decreases erythrocyte carbonic anhydrase activities and impairs cardiorespiratory function in men during exercise." American Journal of Clinical Nutrition 2005; 81: 1,045-1,051