People who consume moderately high levels of Vitamin C have reduced death rates, most notably from heart disease, the leading cause of death in the United States, according to a new UCLA study.
The epidemiological study of 11,348 adults found that men who consumed the most Vitamin C had a 42% lower death rate from all causes than men in the lowest-intake group. Women in the highest-intake group had a 10% lower overall death rate than women who consumed the lowest amounts.
This means that, on average, the men in the highest-intake group would be expected to live six years longer than those in the lowest group and the women one year longer, according to James E. Enstrom, an associate professor at the UCLA School of Public Health and the principal author of the study.
Vitamin C supplements have been touted as an aid to good health and longevity. Surveys indicate that about a quarter of American adults use vitamin supplements on a daily basis and that Vitamin C is the most frequent single vitamin in these supplements.
Many previous studies have suggested a similar link between Vitamin C intake and decreased death rates, but the new report is considered significant because of its size and its ability to control other factors that increase the risk of dying, such as cigarette smoking or a history of serious diseases.
"The studies taken as a whole indicate that if Vitamin C has an effect on human health at all, it is beneficial," Enstrom said. "There is virtually nothing showing that levels of Vitamin C intake in this study are harmful." The study is being published in the May issue of the journal Epidemiology.
Vitamin C, which is also known as ascorbic acid, is believed to prevent disease by neutralizing free radical molecules that can damage cells and contribute to cell aging.
According to Enstrom, the typical person in the highest Vitamin C intake group consumed about 300 milligrams a day--150 milligrams through diet and an additional 100 milligrams or more through a vitamin supplement. Most of those taking supplements used a multivitamin pill; only about 15% of those using Vitamin C pills consumed more than one gram a day.
These levels are considerably higher than the recommended dietary allowance of Vitamin C, which is 60 milligrams per day. But they are considerably less than the megadoses of Vitamin C that have been popularized by Nobel Prize winner Linus Pauling as a cancer treatment. Each day, the 91-year-old Pauling takes 18 grams of Vitamin C, which is 300 times the recommended daily allowance.
Vitamin C is deemed an essential vitamin because the human body cannot manufacture it. It is found in such foods as citrus fruits, tomatoes, potatoes, cabbage, green peppers and broccoli. An eight-ounce glass of orange juice contains about 100 milligrams of Vitamin C.
The study does not recommend how much Vitamin C should be consumed daily. The federal government recommends that people eat five or more servings each day of fruits and vegetables, which should be sufficient to boost daily Vitamin C intake to the 250-milligram range.
Five servings of fruits and vegetables provide "a very nice amount of both Vitamin C and other desirable nutrients," said Gladys Block, a professor of public health at UC Berkeley, who wrote an editorial about the study for the scientific journal.
But in a telephone interview Block cautioned that "Vitamin C is not the only thing that is important. . . . We do not want to give the impression that people can just go out and buy Vitamin C and they have taken care of everything, because there are many things in fruits and vegetables that they won't get in a pill."
Enstrom and two UCLA colleagues analyzed data collected as part of a large national health and nutrition survey organized by the National Center for Health Statistics. Data, including medical history, food consumption and vitamin supplements, was initially collected between 1971 and 1975 and then again between 1982 and 1984. Among the 11,348 adults, there were 1,800 deaths, including 929 cardiovascular deaths and 397 cancer deaths during the study period.
The data was analyzed by grouping the participants based on their Vitamin C intake and correcting for the influence of factors that influence death rates, such as age, sex, race, smoking, education and disease history.
Men in the high-intake group had a 45% lower risk of death from cardiovascular disease then men in the low-intake group, which was defined as less than 50 milligrams of Vitamin C a day. The comparable difference for women was 25%.