Loading up on burgers and deli meats may be tempting, but too much red meat could trigger metabolic changes that upset the body’s glucose balance.
Adding to a growing body of research published over the past two years connecting red-meat consumption to a variety of health problems, a new study appearing in the journal JAMA Internal Medicine documents an association between eating red meat and a greater risk for Type 2 diabetes. It’s only the latest investigation to link the popular protein to chronic diseases like obesity as well as to cognitive decline and even premature death.
Previous studies have also found that people who eat more red meat tend to have higher rates of diabetes, but in the latest analysis, Pan An, an assistant professor at the National University of Singapore, and his colleagues wanted to see if people who started eating more red meat would result in an elevated risk of the chronic condition over time. They studied long-term health data from three Harvard University cohorts that included over 26,300 men participating in the Health Professionals Follow-Up Study; more than 48,700 women in the Nurses’ Health Study; and slightly over 74,000 women from the Nurses’ Health Study II.
All the participants reported on their eating habits through food questionnaires, including their red-meat intake every four years for an average of 20 years of follow-up. During that time, 7,540 people developed Type 2 diabetes. And within each cohort, those who ate more red meat as the study progressed showed higher rates of diabetes than those whose consumption didn’t change.
Those who added more than half a serving of red meat per day from the time the study started showed a 48% greater risk of Type 2 diabetes at the next four-year checkup compared with participants who did not increase intake during that time. Adding more meat to their diet also tended to make them heavier, and that weight gain may have contributed to their higher risk of diabetes, say the authors. On the other hand, people who lowered their red-meat consumption by over half a serving each day from the start of the study enjoyed a 14% lower risk of having Type 2 diabetes over the course of the entire study compared with those who didn’t change how much red meat they ate (the benefits of cutting back on red meat, alas, took longer to unfold than the harms from eating more meat). Rates of diabetes were higher among people who consumed mostly processed meats such as deli fare and hot dogs compared with those who ate unprocessed red meat.
In a editorial accompanying the study, William J. Evans, of GlaxoSmithKline and Duke University in Durham, N.C., pointed out that the results don’t necessarily suggest that red meat is the culprit; instead, the saturated fats embedded in red meats that may be responsible for the health harms to the heart and for upsetting glucose balance:
A recommendation to consume less red meat may help to reduce the epidemic of [Type 2 diabetes]. However, the overwhelming preponderance of molecular, cellular, clinical and epidemiological evidence suggests that public health messages should be directed toward the consumption of high-quality protein that is low in total and saturated fat … These public health recommendations should include cuts of red meat that are also low in fat, along with fish, poultry and low-fat dairy products. It is not the type of protein (or meat) that is the problem: it is the type of fat.
Numerous studies documented that the high levels of saturated fat in red meat are primarily responsible for clogging up arteries, while other types of monounsaturated fats, like those in olive oil, are associated with many health benefits, including lower levels of inflammation. A study from Brigham and Women’s Hospital in March 2012 found that saturated fats and trans fats found in meat and butter were linked to poor cognitive function and memory in women over time, while “good” fats like the monounsaturated fats in avocados and olive oil were connected to better brain function.
(MORE: Vegetarians May Live Longer)
But it may be unfair to put the blame entirely on saturated fats. Another study, published in April, found that human-gut bacteria turn a red-meat compound called carnitine into an artery-clogging agent that in mice caused atherosclerosis, a recipe for blocked blood vessels and heart disease.
Overall, the data seem to hint that red meat may adversely affect health in a variety of different ways that haven’t yet been identified, while a plant-based diet may be beneficial in equally unexplained ways. One of the largest studies to date, for example, recently reported that vegetarians lived longer than their meat-eating counterparts, and the study authors speculate that the longevity may result not just from vegetarians’ avoidance of red meat, but the fact that they benefit from a variety of nutrients found in fruits and vegetables. A comparable British study of the vegetarian diet that included more 47,250 participants did not find the same improvement in longevity, however, which could reflect differences in the types of foods that U.S. and U.K. vegetarians favor; Americans tend to eat more fiber and vitamin C, for example, and both have been associated with lowering risk of cancer and other chronic diseases that can shorten life.
All of which leads nutrition experts to the conclusion that maintaining a healthy diet is not just about cutting out certain foods like red meat and high-fat fare, but making sure you substitute in the right nutritious options. Finding that magic formula for longevity and a disease-free life, however, remains a challenge.