DAN Debunks Antioxidants Before Diving

You may have seen the study making the rounds in publications and on the Internet earlier this year about how antioxidants can reduce hazards to divers’ cardiovascular systems while underwater. The doctors at Divers Alert Network say it’s much ado about nothing.

In a study published in the Journal of Physiology, researchers at the University of Split School of Medicine in Croatia said vitamins C and E can particularly lower divers’ risk for acute endothelial dysfunction, which is the inability of arteries to dilate fully and release nitric oxide, something that can lead to heart attacks and strokes. They gave standard oral doses of vitamins C (two grams) and E (265 milligrams) to divers two hours before a 30-minute dive to 100 feet. Doing cardiovascular tests before and after the dive with ultrasound, they found divers’ pulmonary artery and heart functions were unaffected, and that the vitamins had a positive effect on the vascular endothelium, a layer of cells that regulates and stimulates blood flow throughout the body. Their conclusion: Popping a multivitamin before going underwater can prevent some of diving’s negative effects on your cardiovascular system.

Not so, says Jake Freiberger, M.D., DAN’s associate medical director. The measurement of arteries’ ability to dilate fully and coagulate is purely a research tool, and endothelial dysfunction is a non-specific term. “Chronic endothelial dysfunction is probably bad, but this study did not show that,” he says. Even though the study showed a relationship between endothelial dysfunction and diving, it did not prove that diving was the cause. “I would categorize this as something that happens alongside of something else. The bottom line here is that this is not very meaningful.”

Freiberger recommends that divers not load up on antioxidants anyway, in light of recent reports showing that big doses may not be so beneficial. Results of a study of 232,000 people published in the Journal of the American Medical Association suggest that too much beta carotene, vitamin A, and vitamin E can increase one’s mortality risk, but the effect of vitamin C is still unclear.