By Allison Knott, RD
As with most nutrition topics, there is the constant desire to find the magic bullet – the one food, or group of foods, that will improve our health and lengthen our lives. However, those who study nutrition know a single food is never the answer, but that a diet based on variety is important to health and well-being. You wouldn’t know this, though, when a recent study connecting red meat and mortality was released in March. The headlines read, “Death By Bacon” and “Will Red Meat Kill You?” From CNN to the Huffington Post, every major news organization was reporting on a hot new study from Harvard.
Published in the Archives of Internal Medicine, researchers examined two prospective cohort studies, The Nurses’ Health Study and the Health Professionals Follow-up Study for an association between red meat consumption and mortality. The researchers concluded “…a higher intake of red meat was associated with a significantly elevated risk of total, [cardiovascular disease] CVD and cancer mortality.” Further, according to researcher An Pan, PhD in the Department of Nutrition at Harvard School of Public Health, “In the study population, if all the patients reduced their total red meat intake to less than 0.5 servings per day we estimate a 7-9% reduction in total mortality.”
Study participants submitted dietary intakes at baseline and again every four years in the form of a self-reported food frequency questionnaire between 1980 and 2006. Total red meat consumption ranged from less than one serving to slightly more than two servings per day at baseline and decreased over time (one serving was equal to three ounces in the study population). In addition to the association between red meat and mortality, the results also showed no statistically significant difference between processed and unprocessed red meat and total mortality. However, one would be mistaken in assuming that cutting red meat from the diet would have a direct effect on lifespan. More importantly, it is the other foods consumed in the diet that are most likely to have the greatest effect. The study researchers found that people eating higher amounts of red meat were not eating the other things that have been shown to improve longevity like whole grains, fruits and vegetables. “The question is not whether we should eat red meat or not,” explained Dr. Pan in a brief interview March 15th, “people can eat it definitely, but in the current American diet we are eating it too much and those with a higher red meat intake need to reduce it. Also, people need to limit processed red meats and replace red meat with a healthier source of protein.”
What role does red meat have in the diet?
Alice H Lichtenstein, Senior Scientist and Director in the Cardiovascular Nutrition Laboratory at the Jean Mayer USDA HNRCA at Tufts University, shed some light on the study findings.
“The bottom line is that this study shows an association and cannot address the question of whether there is a cause and effect relationship,” explained Dr. Lichtenstein. “We know that people who consume diets that are higher in red meat frequently engage in other dietary habits that can be associated with increased risk of cancer, cardiovascular disease, and mortality.” The study confirmed, people consuming the most red meat were also more likely to be current smokers, to drink alcohol, have a higher body mass index, and to be less physically active. “There is an attempt to statistically correct for all those factors,” explained Dr. Lichtenstein, “but you may be left with residual confounding, or factors that cannot necessarily be corrected for.” For example, the group eating the highest amount of red meat reported eating 700-800 calories on average more per day. Since the average body mass index (a measure of height compared to weight) were relatively similar across the groups, does that suggest that perhaps one group more completely reported their food intake? Were that the case, how would it affect data interpretation? So, while those study participants who ate a higher amount of red meat reduced their red meat consumption over time, they were additionally engaging in other activities that would increase their total mortality, as well as eating lower amounts of whole grains, fruits, vegetables, and fish.
Does this mean red meat leads to death? No. “The study confirms what we already know – diets low in fruits and vegetables and fish, and high in animal fat are associated with less favorable outcomes,” said Dr. Lichtenstein. While the headlines claim red meat causes death, the take away message is not quite so simple. If you are eating red meat, do so in moderation – choose lean cuts and moderate portion sizes. Consider replacing red meat with poultry, fish, plant-based proteins, and eat plenty of fruits, vegetables, and whole grains.
Allison is a second year Nutrition Communication student and registered dietitian. She has a passion for communicating sound nutrition information to the public. Follow her kitchen blunders, triathlon adventures, and read nutrition advice on her blog, Choices.Habits.Lifestyle.