By Julie Steenhuysen

CHICAGO (Reuters) - 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, Australian researchers reported on Tuesday.

"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.

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 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.

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," Tiganis said in an e-mail.

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.

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

But he said 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 said.

An estimated 23.6 million people in the United States and 246 million people globally have diabetes. Most have type 2, the kind linked with a poor diet and lack of exercise.

(Editing by Maggie Fox)

• More News on Antioxidants
• More News on Diabetes

Related MedlinePlus Pages:

• Antioxidants
• Diabetes