People who regularly eat red meat may have a higher risk of type 2 diabetes later in life, suggest scientists, who after analysing data on 217 000 health professionals, found that those who regularly eat processed meats like bacon, Vienna sausages, and cold meats like polony, have an even greater risk.
However, cutting down on red meat and making other lifestyle changes could help reduce risks, according to Xiao Gu, a nutrition researcher at the Harvard TH Chan School of Public Health and an author of the study, which was published in The American Journal of Clinical Nutrition.
Rates of diabetes are rising in the United States and worldwide, reports The New York Times.
For their study, Gu and his colleagues analysed 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 of beef, pork or lamb every day – had a 62% 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% of the participants were women, and 90% 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. Swopping 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 it’s also high in saturated fat, and “depending on the processing, can be high in sodium and preservatives”.
“None of these is 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,” 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.
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, Mathur said.
A cup of cooked lentils, for example, contains 6.6mg 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, he added.
Study details
Red meat intake and risk of type 2 diabetes in a prospective cohort study of United States females and males
Xiao Gu, Jean-Philippe Drouin-Chartier, Frank Sacks, Frank Hu, Bernard Rosner, Walter Willett.
Published in The American Journal of Clinical Nutrition on 19 October 2023
Abstract
Background
Studies with methodological advancements are warranted to confirm the relation of red meat consumption to the incidence of type 2 diabetes (T2D).
Objective
We aimed to assess the relationships of intakes of total, processed, and unprocessed red meat to risk of T2D and to estimate the effects of substituting different protein sources for red meats on T2D risk.
Methods
Our study included 216,695 participants (81% females) from the Nurses’ Health Study (NHS), NHS II, and Health Professionals Follow-up Study (HPFS). Red meat intakes were assessed with semiquantitative food frequency questionnaires (FFQs) every 2 to 4 y since the study baselines. We used multivariable-adjusted proportional hazards models to estimate the associations between red meats and T2D.
Results
Over 5 483,981 person-years of follow-up, we documented 22,761 T2D cases. Intakes of total, processed, and unprocessed red meat were positively and approximately linearly associated with higher risks of T2D. Comparing the highest to the lowest quintiles, hazard ratios (HR) were 1.62 (95% confidence interval [CI]: 1.53, 1.71) for total red meat, 1.51 (95% CI: 1.44, 1.58) for processed red meat, and 1.40 (95% CI: 1.33, 1.47) for unprocessed red meat. The percentage lower risk of T2D associated with substituting 1 serving/d of nuts and legumes for total red meat was 30% (HR = 0.70, 95% CI: 0.66, 0.74), for processed red meat was 41% (HR = 0.59, 95% CI: 0.55, 0.64), and for unprocessed red meat was 29% (HR = 0.71, 95% CI: 0.67, 0.75); Substituting 1 serving/d of dairy for total, processed, or unprocessed red meat was also associated with significantly lower risk of T2D. The observed associations became stronger after we calibrated dietary intakes to intakes assessed by weighed diet records.
Conclusions
Our study supports current dietary recommendations for limiting consumption of red meat intake and emphasises the importance of different alternative sources of protein for T2D prevention.
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