July 18, 2000 -- Guys, here's another reason to drink your orange juice: A new study has found that men with low blood levels of vitamin C may have an increased risk of dying of cancer. Women who were low in vitamin C seemed to be spared this risk.
These findings echo those of earlier studies showing "that low vitamin C levels put people at risk," lead researcher Catherine M. Loria, PhD, tells WebMD. In those studies, however, the risk is shared by both sexes. Loria isn't certain why these data singled out men.
Loria, an epidemiologist at the National Heart, Lung, and Blood Institute, and her colleagues analyzed data gathered between 1976 and 1980 for the National Health and Nutrition Examination Survey II, a snapshot of the nutritional status of the U.S. population.
In all, more than 9,000 men and women aged 30 to 75 participated. In 1992, the authors followed up with those subjects, looking at their weight, intake of vitamins A and E, blood pressure, diabetes status, and patterns of smoking and alcohol consumption, as well as their levels of vitamin C. More than 7,000 of the original subjects were available for the follow-up study.
During the 12- to 16-year follow-up period, approximately 800 men and 600 women died. The investigators found that men with the lowest blood levels of vitamin C had a 57% higher risk of dying of cancer than did men whose vitamin C was highest. In women, on the other hand, there was no relationship between vitamin C levels and the risk of death from either cancer or heart disease.
"I'm not sure why we didn't see [an increased cancer mortality risk] in women," Loria says. One possible explanation is that women tend to have higher vitamin C levels than men. Also, she says, vitamin C seems to confer its greatest protection against cancers like lung cancer, which, unlike breast or prostate cancer, are not related to hormone levels. Since men were more likely to develop non-hormone-related cancers, they also would be more likely to suffer the consequences of having too little vitamin C.
For example, in this study prostate cancer was responsible for only 7% of the cancer mortality in men, while breast cancer caused 20% of the cancer deaths in women. On the other hand, lung and other cancers of the respiratory tract produced 47% of the cancer mortality in men, compared to 19% in women.
These data "seem to say there's an effect on mortality" when the intake of vitamin C and, possibly other vitamins, is low, says Gail Frank, RD, DrPh, a spokeswoman for the American Dietetic Association.
When people improve their diets, "these types of articles tell us there's a payoff," Frank says. But "doing megadoses of a single vitamin is not the way [to address the situation]," she warns, because it could alter the way the body metabolizes the vitamin. "What we do have in common with two decades ago [when the data were first collected] is the number of servings of fruits and vegetables we have coming in. That has not changed. I continue to be concerned that in the adult population we have not increased our intake of the recommended five servings a day." Frank is a professor of nutrition at California State University in Long Beach.
"Recent surveys suggest that most people [still] aren't getting enough fruits and vegetables, including children, and that's alarming," says nutritionist Ruth Frechman, RD, who reviewed the paper for WebMD. "When my clients go to the grocery store, I suggest that they try [a fruit or vegetable] they've never had before. I also urge them to go to local farmers' markets" to sample locally grown produce. Frechman is a nutrition counselor in Burbank, Calif., and spokeswoman for the California Dietetic Association. Neither she nor Frank was involved in the study.
Loria agrees. "These findings are consistent with dietary guidelines to eat at least five servings of fruits and vegetables a day. Otherwise, people are potentially at risk of developing some chronic diseases," she says. She recommends getting vitamins from foods rather than supplements because food "has many other nutrients, as well as fiber. Certainly, the best approach is to eat a healthy diet."
- A new study shows that men with lower levels of vitamin C have a greater chance of dying from cancer.
- Experts advise getting your daily dose of vitamins from food, rather than from supplements, because food contains many nutrients, as well as fiber.
- Even though guidelines recommend eating five servings of fruits and vegetables each day, most adults in the U.S. do not meet this goal.