No Consensus on Vitamin C’s Benefits

Nutrition experts recommend that Americans take enough Vitamin C to prevent scurvy, a condition that causes anemia and bleeding gums.

The recommended daily allowance, 60 milligrams, is set to accomplish that goal by the U.S. Food and Nutrition Board.

But debate continues whether Vitamin C in larger doses helps prevent cancer, heart disease and colds.

The interest in Vitamin C’s role in cancer prevention largely rests on its ability to disrupt processes in the body that can lead to cancer.

According to this theory, cancer can be promoted by substances called free oxygen radicals, a byproduct of normal cell metabolism. Antioxidants are substances that interfere with free radicals; vitamins C and E are the best known antioxidants.

Support for this theory has led many health experts to recommend that people increase their servings of fruits and vegetables, which are high in vitamins C and E.

But Linus Pauling’s claim that a huge dose of Vitamin C, many times the RDA, can be used to treat cancer is unconfirmed. Despite several studies by Pauling and colleagues that cancer patients consuming high doses live longer, other studies have not verified the claims.

“We know of unequivocal harm from massive doses,” says Dr. Victor Herbert, a researcher at the Mount Sinai School of Medicine. “There is no objective evidence that massive doses have any benefit whatsoever.”

Although not toxic, Herbert says, high doses of Vitamin C can lead to diarrhea, nutritional imbalances, kidney stones and arrhythmia.

And, after years of testing, there is scant evidence to show that Vitamin C can prevent colds, although some researchers say it can ease symptoms.

As for Vitamin C and heart-disease prevention, studies are conflicting, says Patricia Hausman, a nutritionist and vitamin expert:

“Antioxidant properties could very well play a role in heart disease. My advice is to stay very open-minded about it.”

Despite a lack of hard evidence for Vitamin C’s powers, Hausman thinks the current RDA should be higher to reflect what research suggests about its cancer prevention value.

“The current RDA is lagging decades behind our knowledge and our research,” she says. “And it reflects, more than anything, the resistance to change that exists in this profession.”