What to know about the link between red meat and type 2 diabetes

Knvul Sheikh, The New York Times

People who regularly eat red meat may have a higher risk of Type 2 diabetes later in life, according to a large study published in October in The American Journal of Clinical Nutrition. Those who often consume processed meats, like bacon, hot dogs, and lunch meat, have an even greater risk.

Cutting down on red meat and making other lifestyle changes could help many people reduce their risk of Type 2 diabetes, said Xiao Gu, a nutrition researcher at the Harvard T.H. Chan School of Public Health and an author of the study. More than 37 million Americans have diabetes, and 90 to 95 percent of those people have Type 2 diabetes. Rates of the disease — which can also damage the heart, kidneys and eyes — are rising in the United States and across the globe.

For the new study, Dr. Gu and his colleagues analyzed data on nearly 217,000 health professionals who had participated in three large studies spanning several decades. The participants answered detailed questions about their diets and medical histories every two to four years.

After adjusting for other factors, including physical activity and alcohol intake, the researchers found that the more servings of red meat that people ate, the more likely they were to develop diabetes.

Those who ate the greatest amount — roughly two full servings, or about six ounces, of beef, pork or lamb every day — had a 62 percent higher risk of Type 2 diabetes compared with people who ate the least, which was about two servings per week.

The study does not show that eating red meat directly causes Type 2 diabetes; it only shows an association between how much red meat you eat and your risk of disease. More than 80 percent of the participants were women, and 90 percent were white; the researchers found only a weak link between red meat and Type 2 diabetes in Asian and Hispanic people, because the number of participants in these categories was so low.

But the study’s findings echo other research that raises concerns about eating large amounts of red meat, and suggest that dietary changes could make an impact. Swapping just one serving of meat per day with plant-based sources of protein — like nuts and legumes — or with a dairy product like yogurt also lowered diabetes risk, according to the study.

Why might red meat be harmful to your health?

“Red meat has pros and cons,” said Dr. Ruchi Mathur, an endocrinologist at Cedars-Sinai in Los Angeles who was not involved in the study. It’s a valuable source of protein, vitamins like B12, and minerals such as selenium. But red meat is also high in saturated fat, and “depending on the processing, can be high in sodium and preservatives,” Dr. Mathur said. “None of these are good for our health.”

Previous research has linked saturated fat to insulin resistance in overweight and obese adults. And in animal studies, high levels of sodium and chemical preservatives like nitrates and nitrites, found in cured meats, have been shown to increase inflammation and damage cells in the pancreas, which makes insulin. People develop Type 2 diabetes when their bodies are unable to produce enough insulin.

Red meat also has high levels of a type of iron called heme, which researchers believe can affect insulin production.

“But the debate is far from settled,” Dr. Mathur said. Most studies showing a link between red meat and diabetes in humans have been observational and have relied on people accurately reporting what they ate over the course of a year. People who eat more red meat and are more likely to have diabetes also tend to have a higher body mass index and be less physically active, and they are more likely to be smokers, though researchers try to control for these factors through mathematical models.

What do the findings mean for your diet?

If you eat red meat every day, it might be a good idea to scale back. “The lower you go, the better,” Dr. Gu said, adding that one serving a week is a good goal.

Although most Americans eat more red meat than nutrition experts recommend, data suggest that we are eating a little less beef and a little more fruit than we did in the 1970s, when the first study included in the new research began. But consumption of refined carbohydrates and sweetened beverages, which can also contribute to diabetes, has increased.

If you decide to eat less red meat, what you substitute for it is “extremely important,” Dr. Gu said.

Previous research has suggested that eating poultry instead of processed meats could decrease diabetes risk. Seafood and soy-based products like tofu can also be healthy, high-protein alternatives, as can plant-based sources of protein such as beans, lentils, nuts and whole grains. Many of these can also help add non-heme iron to your diet, Dr. Mathur said. A cup of cooked lentils, for example, contains 6.6 milligrams of iron — more than the amount found in a serving of beef. Consider adding vitamin C from some lemon juice, tomatoes, or bell peppers to your meals to help your body absorb non-heme iron.

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