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Why Antioxidant Supplements May Harm, Not Help

A new study from researchers at University of Bonn and Harvard gives a plausible explanation for the negative effects of antioxidant vitamins that have been reported in several previous studies. They show that people who take 1000 mg/day of vitamin C and 400 IU/day of vitamin E do not gain the benefits of increased insulin sensitivity when they exercise (Proceedings of the National Academy of Sciences, May 12, 2009). Here's a detailed explanation of this important finding:

• When blood sugar levels rise too high, sugar sticks on the surface of cell membranes and can never get off; it is converted in a series of chemical reactions to sorbitol that destroys cells.

• Contracting muscles help to prevent this damage by removing sugar so fast from the bloodstream that blood sugar levels do not rise too high.

• Food is converted to energy to power your muscles by a series of chemical reactions that shuffle electrons from molecule to molecule.

• This occurs primarily in the mitochondria, small energy- producing chambers in cells, that number anywhere from a few to thousands in each cell.

• As electrons are shuffled to produce energy, extra electrons can accumulate. They can either end on hydrogen atoms to form water and become harmless, or they can end up on oxygen atoms to form free radicals that can damage cells. This can cause cancers, heart attacks and other life-shortening conditions.

• Exercise speeds up the reactions that turn food into energy. So exercise increases the production of free radicals.

• The body responds to this increased production of free radicals during exercise by producing tremendous numbers of antioxidants that sop up the free radicals and render them harmless.

• Exercise prolongs life and prevents heart attacks and cancers by causing the body to dispose of free radicals by the increased production of antioxidants.

• This new study explains that if you exercise and take antioxidant vitamins C and E, you prevent your own body from making large amounts of antioxidants during exercise, so more free radicals (oxidants) accumulate in your body and more cells are damaged.

This study reinforces the recommendations I have given for years: Exercise every day, and get the antioxidant vitamins and other nutrients your body needs from foods, not from pills. Eat a wide variety of foods including large amounts of fruits, vegetables, whole grains, beams, nuts and other seeds.


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Dear Dr. Mirkin: How can I tell if I'm improving my level of fitness?

The best way is to race and see how much faster you become. However, you don't need to do that. You can also use a simple test called Heart Rate Recovery. Tim Noakes, a former marathon runner, followed competitive bicycle racers through a four-week very-intense training program and showed that a simple test that can be done by anyone, Heart Rate Recovery, was as accurate as a measurement of improvement as more sophisticated and expensive tests, such as peak power output, VO(2max) or a 40-km time trial (European journal of applied physiology, March 2009).

This test should be done only by people who have no hidden heart disease, since exercising to your maximum can cause a heart attack in people who have damaged hearts. Exercise as hard as you can, close to the fastest your heart can beat, for at least a few minutes. Use a heart rate monitor to check your pulse just before you stop and then again one minute later. If you are fit, your heart rate will drop 30 beats or more in the first minute. As your level of fitness improves, your heart rate recovery increases also.


Dear Dr. Mirkin: My blood pressure was 145/95 in my doctor's office but when I checked it at home that night it was 115/75. Should I take medication to lower my blood pressure?

That's a decision between you and your doctor, but be sure he is aware of the latest research. This month, a study from Brazil shows that the people who are most likely to suffer heart attacks, strokes and premature deaths are those whose blood pressures do not dip below 120/80 before they go to bed and when they first wake up (Archives of Internal Medicine, May 13, 2009). Most healthy people have their blood pressure dip in the evening. More on blood pressure


Recipe of the Week:

Shrimp Confetti Chowder

You'll find lots of recipes and helpful tips in The Good Food Book - it's FREE

June 22nd, 2013
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About the Author: Gabe Mirkin, MD

Sports medicine doctor, fitness guru and long-time radio host Gabe Mirkin, M.D., brings you news and tips for your healthful lifestyle. A practicing physician for more than 50 years and a radio talk show host for 25 years, Dr. Mirkin is a graduate of Harvard University and Baylor University College of Medicine. He is board-certified in four specialties: Sports Medicine, Allergy and Immunology, Pediatrics and Pediatric Immunology. The Dr. Mirkin Show, his call-in show on fitness and health, was syndicated in more than 120 cities. Read More
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