Researchers at Vanderbilt University and the National Institutes of Health say that recommended daily allowance of vitamin C for healthy young women should be raised from 75 to 90 milligrams a day.
Eating a variety of fruits and vegetables can more than satisfy the recommended allowance, said Dr. Mark Levine, lead author of a new study supporting the increase for women.'We've been recommending, as have other groups, that both men and women consume at least five varied servings of fruits and vegetables a day,Levine said. `That's where the benefit is in cancer prevention, increasing life span and perhaps in preventing heart disease.
Vitamin C is an anti-oxidant and has been touted as a way to fight off the common cold and cancer. In the study of healthy young women, however, the vitamin did not change the level of isoprostanes, compounds that may play a role in cell and tissue damage caused by free radicals and other highly reactive molecules.
That does not mean that the vitamin isn't important in less healthy people, including smokers, who tend to have higher levels of isoprostanes, said Dr. Jason Morrow, professor of medicine and pharmacology at Vanderbilt. That research has yet to be done, he added.
Morrow and Dr. Jackson Roberts, also a professor of medicine and pharmacology at Vanderbilt, discovered isoprostanes in 1990. Since then, the compounds have become the best measure of oxidant stress,a damaging process accelerated by smoking and other conditions that may contribute to heart disease and cancer, he said.
The recommended daily allow-ance of vitamin C was raised last year by the National Academy of Sciences from 60 milligrams a day for both sexes to 75 milligrams for women and 90 milligrams for men. That recommendation was based only on studies in men, however. It assumed that women, who tend to have less muscle than men, would need less vitamin C, said Levine, chief of molecular and clinical nutrition at the National Institute of Diabetes and Digestive and Kidney Diseases.