Negative effects of vitamins on voles cast doubt on health supplement benefits

Vitamin C and vitamin E dramatically reduce the lifespan of voles, biologists have found, raising questions about the benefits of vitamins as a health supplement.

11 july 2013--A new paper published in the journal Biology Letters explains the research. The team fed field voles a diet supplemented with high levels of vitamin E or vitamin C from the age of two months in either warm or cold conditions and compared their longevity to groups of voles fed a regular diet.

High doses of dietary antioxidants such as vitamins are commonly suggested to slow the process of cellular ageing by lessening the damage to proteins, lipids and DNA caused by free radicals.

Previous research conducted by the team had shown that the longevity of mice could be extended by administering particular vitamin supplements, despite the supplements' limited effectiveness in reducing free radical damage.

However, the opposite was found to be true in voles. Voles in cold conditions fed supplements of vitamin E or vitamin C lived much shorter on average than those fed a regular diet. Similarly, in warm conditions, supplemented voles fed vitamin E or vitamin C lived much shorter than those fed a regular diet. Compared to animals on a regular diet, lifespan was reduced by 11% and 26% for vitamin E and C voles in the cold and by 17% and 18% for vitamin E and C voles in the warm. Despite the effect on the voles' lifespans, the researchers found that the vitamin supplements did have some effect in decreasing free radical damage.

Professor Colin Selman of the University of Glasgow's Institute of Biodiversity, Animal Health and Comparative Medicine, who was first author on the work, said: "When we began our research, we expected that voles' lifespans would be boosted by the vitamin supplements in a similar way to the mice we had tested previously, so we were surprised to see that was not the case. Our findings suggest that major differences exist in the effects of high doses of antioxidants on oxidative damage and lifespan across species."

Professor John Speakman, of the University of Aberdeen, who led the work, said: "It's unlikely that randomised controlled trials examining the effects of antioxidant supplementation on human lifespan would be possible, so we are dependent on the results of animal studies. It's impossible at this stage to extrapolate the results from this small amount of data we have on voles and mice but it does suggest that caution is warranted in the use of high doses of antioxidant vitamins."

More information: The paper, titled 'Deleterious consequences of antioxidant supplementation on lifespan in a wild-derived mammal', is published in Biology Letters and is available online atrsbl.royalsocietypublishing.org/content/9/4/20130432.full

Provided by University of Glasgow

Report warns of problems with multivitamins

NEW YORK, 11 april 2009-- More than 30 percent of multivitamins tested recently by ConsumerLab.com contained significantly more or less of an ingredient than claimed, or were contaminated with lead, the company reports.

ConsumerLab.com, based in White Plains, New York, is privately held and provides consumer information and independent evaluations of products that affect health and nutrition. According to the company, it is neither owned by nor has a financial interest in any companies that make, distribute or sell consumer products.

Several multivitamin products tested, including three for children, exceeded tolerable upper limits established by the Institute of Medicine for ingredients such as vitamin A, folic acid, niacin and zinc, according to the report posted on www.ConsumerLab.com.

For example, the Institute of Medicine sets a recommended daily allowance (RDA) of 1,300 international units (IU) of vitamin A for children ages 4 to 8 years and an upper tolerable limit of 3,000 IU. However, one multivitamin tested provided 5,000 IU of vitamin A.

In the short term, too much vitamin A may cause nausea and blurred vision, and, in the long-term, may lead to bone softening and liver problems.

Upper tolerable limits for niacin and zinc were also exceeded by some of the supplements for young children tested. Excess niacin may cause skin tingling and flushing and high levels of zinc may cause immune deficiency and anemia.

Tests turned up problems with some men's multivitamin products as well. Two of three men's multivitamins failed to pass testing. One contained too much folic acid, which may increase the risk of prostate cancer, while another was contaminated with lead.

Among four women's multivitamins tested, one provided only 66 percent of its claimed vitamin A; one of five seniors' multivitamins selected contained only 44 percent of its vitamin A; and among three prenatal vitamins, one was short on vitamin A.

Two out of five general multivitamins were short on ingredients: one provided only 50 percent of its claimed folic acid and the other was missing 30 percent of its calcium.

A vitamin water tested by ConsumerLab.com had 15 times its stated amount of folic acid, so drinking one bottle would exceed the tolerable limit for adults; less than half a bottle would put children over the limit, the company warns on its website.