Red meat raises diabetes risk: how to lower it

By Deborah Kotz, Globe Staff

If you’re worried about getting diabetes, you may be watching your diet, trying not to eat too many bagels, muffins, and other processed carbohydrates -- but have you ever thought of skipping the steak, hot dog, or burger? A study published today in the American Journal of Clinical Nutrition suggests that eating as little as one serving a day of red meat increases your risk of type 2 diabetes, the kind that typically affects adults and often occurs when cells stop responding to the hormone insulin.

“We found that one serving per day of processed meat like a hot dog or sausage was associated with a 50 percent increased risk of diabetes” compared with people who ate processed meat less than once a month, said study co-author Dr. Frank Hu, a professor of nutrition and epidemiology at the Harvard School of Public Health. “That’s pretty high.”

Unprocessed meat, including steak, hamburgers, and pork chops, raised diabetes risk by 20 percent in those who ate at least four ounces a day, compared with those who ate that amount once a week.

Study participants had about a 7 percent risk, on average, of developing Type 2 diabetes over course of the studies ranging from 14 years to 28 years; a 50 percent increase in risk would raise that to a 10.5 percent risk, while a 20 percent increase in risk would raise it to 8.4 percent.

There are scientific reasons to explain the finding, which was gleaned from dietary surveys of more than 200,000 participants in the Harvard Nurses’ Health and the Health Professionals Follow-up studies. The high iron content of red meat can increase inflammatory chemicals, which can destroy insulin-producing beta cells, said Hu. The nitrates in processed meats may also be toxic to beta cells, which could explain why processed meats contributed even more to risk. Whether the high saturated fat content contained in red meat also contributes to an increase in inflammation remains unknown.

Lastly, those who ate the most red meat also tended to eat fewer fruits and vegetables and were more likely to smoke and be obese. While the study used statistical methods to account for all of these lifestyle factors -- which also contribute to Type 2 diabetes risk -- it’s tough to account for all the variables when observing the habits of populations and drawing conclusions from them. As the researchers themselves admitted at the end of the study, “observed associations do not necessarily mean causation.”

In fact, some, like science writer Gary Taubes, may take strong issue with the finding since they strongly believe that sugar is largely to blame for the sharp increase in diabetes that’s occurred in our nation. (Read more about this in the raging debate on why we get fat.)

But Hu contends the finding sends a clear message that Americans should be emphasizing more of a plant-based diet and looking for other sources of protein such as nuts, fish, low-fat dairy, and poultry. “I think we should change our mindset in terms of protein sources in our diet.”

For example, a July study in the same journal found that eating three servings of low-fat dairy products every day led to a decrease in inflammatory chemicals that are associated with metabolic syndrome, a condition that frequently leads to diabetes. “This not only decreases diabetes risk, but heart disease risk as well,” he added.

Exercise -- especially resistance training -- may also have a big impact in helping to prevent diabetes. Each 10 percent increase in muscle can decrease your type 2 diabetes risk by 12 percent, according to a study published in the Journal of Clinical Endocrinology and Metabolism.

“Muscle helps the hormone insulin work better,” Hu explained, “so you get better glucose uptake from your blood,” which means blood sugar levels are less likely to rise to dangerously high levels.

Avoiding smoking can also lower your diabetes risk by keeping blood sugar levels on a more even keel. And managing stress may aid prevention efforts as well since the stress hormone cortisol appears to play a role in the accumulation of visceral fat -- the kind that produces inflammation and is linked to diabetes.