Vitamin E gives mice a longer, more acrobatic life

17:00 02 September 2005
NewScientist.com news service
Gaia Vince

Vitamin E improved the acrobatic prowess of mice given a tightrope walking test, well into old age

Vitamins face tough safety tests in Europe
High doses of vitamin E may help mice live longer, according to a new study by Spanish and Argentinean researchers.

Male mice given the vitamin lived an average 40% longer than their peers and showed a much higher level of acrobatic prowess when they performed on a high-wire tightrope, the researchers found. The improvements were due to the vitamin’s antioxidant properties, they say.

The mice used in the study were of a strain with accelerated ageing, with an average lifespan of 61 weeks. At 28 weeks of age half of the study’s 300 mice were given daily supplements of vitamin E, equivalent to a dosage of about 1.2 - 2.2 grams per day in humans (a level which is as much as five times the upper limit recommended by the US national dietary guidelines).

The mice that had received vitamin E supplements lived an average 85 weeks – 40% longer than normal. No negative side effects of the high dose were observed by the researchers.

Free radicals
But long life is not necessarily associated with quality, so Ana Novarro and colleagues from the University of Cadiz in Spain, and Alberto Boveris and colleagues from the University of Buenos Aires in Argentina, looked at the creatures’ abilities to perform various tests.

They found that those on the vitamin E diet were better than the others at crossing a 50 centimetre-high wire tightrope and negotiating a T-shaped maze. And as they reached a grand old age (78 weeks), the differences were more stark – while those on a normal diet deteriorated rapidly, the mice given regular vitamin E continued to perform well, performing up to 45% better at tests.

“The vitamin acted as an antioxidant in the mice, slowing the ageing process,” Boveris explains. They found that the mice that had received vitamin E showed reduced levels of free radical mediated reactions and oxidative damage in their mitochondria, the cell’s power packs, than other mice.

“Normally in ageing there is an increase in products of oxidation, but the mice on vitamin E actually showed a reduction. And the protective effects were particularly noticeable in the brain,” Boveris says. He admits that he has increased his personal intake of the vitamin to 400 mg per day.

Hastening death
The researchers also found that vitamin E supplements were “able to prevent the decrease in the activities of brain enzymes that are mitochondrial markers of ageing” by substantial levels.

The findings contrast with those of a small 2004 meta-study into daily doses of vitamin E in humans, which found that the supplement may hasten death in high doses. The lead author of that study, Edgar Miller from Johns Hopkins University School of Medicine in Baltimore, US, suggested that in high doses the vitamin could increase bleeding and stroke risk in people taking blood thinning drugs, or that it may become a “turncoat” free radical and damage the proteins and fats it usually protects.

Boveris and Novarro are about to begin a new study in mice to see if they can repeat their results with smaller doses of vitamin E.

The new research appears in the online edition of the American Journal of Physiology-Regulatory, Integrative and Comparative Physiology.

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High doses of vitamin E may hasten death
15:00 10 November 2004
NewScientist.com news service
Maggie McKee

Taking high doses of vitamin E may increase a person’s overall risk of dying in any given year, according to a controversial new analysis. The US researchers say the finding - whose cause is unknown - suggests people should stop taking high doses of the popular supplement.

Earlier studies suggest vitamin E, an antioxidant, has either no effect on mortality rates or lowers the risk of dying from cardiovascular disease. And unlike some other antioxidants, such as vitamin A, vitamin E does not accumulate in the body, potentially becoming toxic.

So US dietary guidelines, while not recommending vitamin E supplements, set a high upper limit of 1500 international units (IU) for their daily intake. Most of the 25% of US adults who take vitamin E supplements take them in large doses - greater than 400 IU per day.

"People take high doses because they think they’re going to live longer," says lead author Edgar R. Miller, a physician at Johns Hopkins University School of Medicine in Baltimore, Maryland. "But this research doesn’t support that. The death rate is higher with high doses."

Vitamin overdose
Miller says previous studies have been small and not taken dosage into account. But he and his colleagues analysed the dosage levels and death rates of about 136,000 people in 19 clinical trials conducted around the world.

They found that the risk of dying within five years rose by about 5% in the 11 trials with vitamin E doses of at least 400 IU per day. The effect of low-dose supplements, however, lowered the risk of death by less than 1%. The researchers presented their results on Wednesday at a meeting of the American Heart Association in New Orleans, Louisiana. They will publish the work in the Annals of Internal Medicine.

But the authors caution that the results may not apply to the population at large because the high-dose trials were small and their participants tended to have chronic health problems such as heart disease. And because most of the studies did not note the cause of death, the authors say they cannot conclude anything about the underlying mechanism.

But they list four possible causes. Vitamin E is an anti-coagulant, so it may increase the risk of bleeding - which contributes to strokes - in people already taking blood-thinning drugs. Or it could be down to the irregular way people take the supplement. Withdrawal symptoms, such as chest pain, may start when people stop their daily regime.

Rogue compound
Or, say the researchers, vitamin E could become a “turncoat” free radical at high doses, damaging the very proteins and fats it usually protects.

Maret Traber, a nutritionist at Oregon State University in Corvallis, who helped develop the US guidelines for vitamin E, says the turncoat effect has been seen in test tubes. But she notes that the human body may contain enough other antioxidants to neutralise a rogue vitamin compound immediately.

"It’s kind of like a little spark flying out of the fireplace - the vitamin E radical never stays around long enough to actually do any damage," Traber told New Scientist.

Finally, the researchers say the type of vitamin E in supplements could displace other antioxidants - including another form of vitamin E found in many foods, disrupting the balance of antioxidant systems.

"It’s difficult to figure out why vitamin E should cause death," says Traber, who points out that the new analysis looked only at studies in which people died.

But Stephen Bent, a physician who studies herbal supplements at the University of California in San Francisco, says: "Most of the evidence really hasn’t panned out that vitamin E is a very beneficial supplement. So to think that high doses might be harmful is not that surprising."

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