Professor: Antioxidants bad for diabetes

Antioxidants - the compounds that prevent cell damage and aging may contribute to the development of diabetes, according to a new study led by Professor Tony Tiganis of Monash University.

Antioxidant supplements are designed to eliminate reactive oxygen species (ROS) aka free radicals and hydrogen peroxide in our body, which in large amounts can cause chronic disease.

But strangely enough, they might be doing more harm than good, as the research suggests that ROS may have a protective effect early in the development of Type Two diabetes.

“Insulin is the primary hormone responsible for lowering blood glucose after a meal,” explained Professor Tiganis. “In Type 2 Diabetes, insulin resistance develops; a condition where the response to insulin in diminished.

“Our studies indicate that low levels of ROS early in disease progression may promote the insulin response and thus prevent the onset of insulin resistance.”

Tiganis and his team studied the effects of ROS in two groups of mice fed a high-fat diet for 12 weeks.

One group of mice lacked an enzyme that prevented them from eliminating ROS as they otherwise would have.

The results showed that mice lacking the enzyme were less likely to develop insulin resistance, an early sign of diabetes, than the normal group of mice.

However when the enzyme deficient mice were treated with an antioxidant, they lost this benefit, leaving the mice with more signs of diabetes.

“Under normal circumstances ROS may be working not to damage the body but to inhibit enzymes that serve to turn off the insulin signal,” Tiganis explained.

Although the studies were conducted in mice, Tiganis said the study provides a cautionary note to the use of antioxidants in humans.

“Taking antioxidant supplements in otherwise healthy individuals is a practice that should be discouraged,” he said.

“A healthy diet that includes a natural source of antioxidants, and exercise, which is a natural source of ROS, is recommended.”

Tiganis added that eating a balanced diet of antioxidant-rich fruit and vegetables is unlikely to reach the antioxidant levels that may cause harm.

The professor’s study, which appears in the journal, Cell Metabolism is not the first to show the negative effects of antioxidants.

Studies in worms and some clinical trials in humans have also suggested that antioxidants can shorten life span.

“Clinical studies have not provided any clear evidence for the beneficial action of antioxidants in the prevention of Type 2 diabetes or for that matter cancer,” Tiganis added.

The professor and his team will continue their research to determine when the amount of ROS goes from being beneficial to detrimental. They are also planning to conduct further studies in humans in the near future.