07 October 2009

Antioxidants may up diabetes risk

Instead of protecting against diabetes, antioxidants may actually increase the chances of getting diabetes, at least in the early stages, hints research conducted in mice.


Instead of protecting against diabetes, antioxidants – compounds in foods and supplements that prevent cell damage – may actually increase the chances of getting diabetes, at least in the early stages, hints research conducted in laboratory mice.

"In the case of early type 2 diabetes... our studies suggest that antioxidants would be bad for you," Tony Tiganis of Monash University in Australia, whose study appears in the journal Cell Metabolism, said in a statement.

He cautioned that the study was in mice and more study in people is needed.

A delicate balance
Antioxidants can prevent cell damage caused by charged particles known as reactive oxygen species. This oxidative stress is thought to add to the progression of several diseases, including type 2 diabetes.

Because antioxidants fight oxidative stress, they have become a popular food supplement. But Tiganis said the picture appears to be a bit more complicated.

"We think there is a delicate balance, and that too much of a good thing – surprise, surprise – might be bad," he said.

Mice become 'more diabetic'
Tiganis' team studied the effects of oxidative stress in mice fed a high-fat diet for 12 weeks. One group of mice lacked an enzyme known as Gpxl, which helps counter oxidative stress.

They found mice that lacked the enzyme were less likely to develop insulin resistance – an early sign of diabetes – than normal mice. But when they treated the enzyme-deficient mice with an antioxidant, "they lost this advantage and became more 'diabetic," Tiganis said in an email.

He said oxidative stress may be working not to damage the body but to inhibit enzymes that hurt the body's ability to use insulin early on in the development of diabetes, and that antioxidants remove this protective mechanism.

"Our work suggests that antioxidants may contribute to early development of insulin resistance, a key pathological hallmark of type 2 diabetes," Tiganis said.

Beware of taking antioxidants
Other studies have suggested that antioxidants can shorten lifespan in both worms and humans. And clinical trials in people have shown that taking antioxidants doesn't protect healthy people from developing diabetes.

"My belief is that individuals who are otherwise healthy shouldn't take antioxidants, but rather eat healthy and exercise," he said.

Health24's DietDoc, Dr Ingrid van Heerden, echoed Tiganis in saying that the study was conducted with mice and that all research results obtained with experimental animals can't be directly extrapolated to humans. "Confirmation must come from human studies before the findings are applied to humans," she told Health24 in an e-mail.

"The general approach used by dieticians and nutritionists nowadays is that healthy individuals don't need to take supplements (vitamins, minerals, antioxidants, etc) as some research in humans indicates that excessive intakes of any supplement can be potentially harmful," she furthermore commented. "Nutrients should be obtained from a balanced, varied diet."

(Reuters Health, October 2006)

Read more: Antioxidants: powerful protectors


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