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Antioxidants may raise diabetes risk

Australian researchers have found that antioxidants may increase your risk of developing diabetes in the early stages.

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

Antioxidants are protective proteins that 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 says 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 says.

Removing protective mechanism

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 become more diabetic," says Tiganis.

He says 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," says Tiganis.

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

But he says other studies have suggested that antioxidants can shorten lifespan in both worms and humans. And clinical trials in people have shown that taking antioxidants does not protect healthy people from developing diabetes.

"My belief is that individuals who are otherwise healthy should not take antioxidants, but rather eat healthy and exercise," he says.

According to the 2004-05 Australian National Health Survey, 582,800 people (approximately 3% of the population) reported having type 2 diabetes.