Lower Vitamin C Means Higher Cancer Risk for Men
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
Death from heart disease also was high in men with the lowest vitamin C
levels, but that increase disappeared when other heart disease risk factors
were taken into account.
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.