Battling blood sugar: environment and diet are factors in rising adult-onset diabetes. (Your Health).

Seventeen million Americans have diabetes, and the incidence of new cases has increased 32 percent since 1990, according to the U.S. Centers for Disease Control and Prevention. People are being diagnosed at younger and younger ages. Experts are still searching for the cause, but most say it is related to high-fat diets and a lack of exercise. "It's really mirroring the increasing trend of obesity," says Dr. Francine Kaufman, president of the American Diabetes Association. Many scientists believe diets heavy in highly refined carbohydrates and environmental factors also play a significant role.

Dioxin exposure may be the most significant environmental risk factor for adult-onset, or Type II, diabetes. Dioxin is a chemical byproduct of industrial processes that use chlorine, from plastic production to waste incineration. It accumulates in fatty tissue and causes several health problems, even at low levels. Dioxin is an endocrine disrupter, and diabetes is a disease of the endocrine system.

An Agent Named Orange

The most intensive studies of diabetes and dioxin focus on Vietnam veterans who sprayed the dioxin-laced herbicide Agent Orange. As compared to a control group, veterans with the highest exposures were found to be 50 percent more likely to develop adult-onset diabetes.

Veteran Rick Weidman says he was exposed to Agent Orange. "I was a medic and we sprayed it from backpacks," Weidman says. "It got on your hands, soaked into your clothes and blew into your mouth." Weidman, who now suffers from a degenerative eye disease, says nobody in the field knew Agent Orange had dioxin in it. "No safety precautions were taken," he adds.

A report published by the National Academy of Sciences' Institute of Medicine, Veterans and Agent Orange: Update 2000, further strengthened the case for a link between diabetes and dioxin, says epidemiologist David Strogatz of the State University of New York at Albany. For example, some of the original studies continued to show a stronger association over time, even after adjustment for other risk factors such as obesity.

The National Institutes of Health showed a connection between dioxin exposure and diabetes in Vietnam veterans who did not work directly with Agent Orange. "Those with higher background levels of dioxin had a greater risk for diabetes," says Dr. Arnold Schecter, a professor at the University of Texas School of Public Health.

Background Dioxin

It's still unclear whether the background levels of dioxin we encounter in everyday life could be contributing to the rising number of diabetes cases, experts say. But Schecter says it makes sense to reduce your dioxin exposure just in case. The U.S. Environmental Protection Agency (EPA) estimates we absorb approximately five parts per trillion of dioxin in our bodies from the air, water and food.

High-fat meats, fish and dairy products are laden with the most dioxin, Schecter says, so cut back on those first. Schecter studied a group of 30-year vegans and found they had extremely low levels of dioxin. Under a low-fat dioxin elimination plan, it takes three to 11 years to cut the amount of the chemical in your system in half, he says.

The real solution is to prevent factories from dumping dioxin into the environment in the first place, says Monica Rohde, director of the Stop Dioxin Campaign for the Center for Health, Environment and Justice. So far, industry has been arguing the science doesn't prove dioxin is a health threat, Rohde says. "The Vietnam veterans' experience has helped show there's a link," she adds. The center is lobbying the EPA to release its dioxin reassessment, which will spell out risks. "Let's keep studying it, but let's also put some policy in place to reduce the level of dioxin accumulating in people," Rohde says.

Redefining Your Diet

When it comes to diabetes, however, fast food and too much television can be more toxic than dioxin, says Dr. Rich Jackson, senior investigator at Harvard University's Joslin Diabetes Center. While sometimes genetics can work against you, the best way to avoid developing diabetes is to eat right and exercise more. In one study, Jackson found that walking 20 minutes per day helped subjects reduce their incidence of diabetes by 50 percent.

The magazine Taste for Life wrote last year, "Adult-onset diabetes can't develop without a steady supply of carbohydrates." The publication proposed a possible link between diabetes and "the modern American diet of highly processed snacks, white bread, refined pasta, sweetened cereals and candy bars, which cause abnormal elevations of blood glucose."

Taste for Life advises consumers to minimize such processed foods, and also to limit soft drinks and partially hydrogenated vegetable oils (like corn oil). In contrast, a diet rich in whole fruits and vegetables may help prevent onset diabetes. Specifically, alpha-lipoic acid, vitamin C and trivalent chromium (as in the form chromium picolinate) are thought to be preventative. The herbs milk thistle seed, American ginseng and dandelion root may also help keep blood sugar levels in balance. CONTACT: Center for Health, Environment and Justice, [phone], www.chej.org.

MELISSA KNOPPER is a Denver-based freelance science writer.