Red Meat Associated with Increased Mortality

Red Meat Associated With Increased Mortality Risk
By Kristina Fiore, Staff Writer,
MedPage TodayPublished: March 23, 2009
Reviewed by Zalman S. Agus, MD; Emeritus Professor University of Pennsylvania School of Medicine.
BETHESDA, Md., March 23 -- People who chow down on too many steaks and hamburgers may have shortened life expectancies, researchers reported in a massive study of aging Americans. Greater consumption of red and processed meat was associated with an increased risk of mortality, particularly from cancer or cardiovascular causes, Rashmi Sinha, Ph.D., of the National Cancer Institute, and colleagues reported in the March 23 issue of Archives of Internal Medicine. On the other hand, eating more white meat slightly decreased total and cancer mortality. Previous research had found that consuming red or processed meat was associated with increased mortality, but the connection had been ambiguous because of various confounding factors.
Action Points
Explain to interested patients that a large prospective study found that eating more red and processed meat is associated with an increased risk of mortality, particularly from cancer and cardiovascular causes. Note that conversely, white meat had a small protective effect against total and cancer mortality. To focus more tightly on the red meat-mortality relationship, the researchers analyzed the eating habits of more than half a million men and women enrolled in the long-term, prospective NIH-AARP Diet and Health study. The volunteers, aged 50 to 71 from eight states, filled out a 124-item food frequency questionnaire to assess dietary habits.
Over 10 years of follow-up, there were 47,976 male deaths and 23,276 female deaths.
The researchers found an increased risk of total, cancer, and cardiovascular mortality among both men and women who were in the highest quintile of red meat intake (66-68 g/1000 kcal), compared with those in the lowest quintile (about 9 g/1000 kcal, P<0.001). Similar results were found when comparing the highest and lowest quintiles of processed meat intake (P<0.001). Conversely, white meat consumption had an inverse association with total and cancer mortality in both sexes (P<0.001). However, there was a small increase in risk of cardiovascular mortality in men who ate more white meat (HR 1.05, 95% CI 1.00 to 1.11, P=0.009). For the purposes of the study, there was some overlap in food categories, so they were not mutually exclusive. For example, red meat comprised all types of beef and pork, but also included bacon, hot dogs and some other processed products. Also, processed meat included lunch meats, sausages, and cold cuts made with red or white meat. White meat, meanwhile, included chicken, turkey, fish, canned tuna and processed meats made from those sources. The authors created 3 diet types: high- medium-, and low-risk meat diets. To form these diet variables, red and white meat consumption was energy adjusted and split into two groups using the median values as cut points. Individuals with red meat consumption in the upper half and white meat consumption in the lower half got a score of 1 (high-risk meat diet). Those with both red and white meat consumption in the same half got a score of 2 (medium-risk meat diet), and those with red meat consumption in the lower half and white meat consumption in the upper half got a score of 3 (low-risk meat diet). The researchers cited a variety of possible mechanisms in the relationship between red meat and mortality. First, meat is a source of several carcinogens, including N-nitroso compounds, as well as heterocyclic amines and polycyclic aromatic hydrocarbons, both of which form when meat is cooked.
Also, the iron in red meat may increase oxidative damage and increase the formation of N-nitroso compounds, the researchers said. Meat is also a major source of saturated fat, which has been associated with breast and colorectal cancer, and intake of red and processed meat has been associated with elevated blood pressure. The researchers said their results may have limited application to the general population since the study cohort was predominantly non-Hispanic white. It was also more educated than the general population, consumed less fat and red meat but more fiber, fruits, and vegetables, and had fewer current smokers. Reaction from the beef industry was mildly critical but subdued. "As is often the case with epidemiological research on this subject, it is hard to draw substantial conclusions about any one food," Shalene McNeill, PhD., Executive Director for Human Nutrition Research at the National Cattlemen's Beef Association, said in a written statement. "This latest research is complicated by the fact that study participants exhibited unhealthy behaviors such as smoking, lack of physical activity, and maintaining a higher body mass index which are known risk factors for chronic disease. What can be concluded from this study is that a balanced diet and overall healthy lifestyle can make a difference in helping prevent chronic disease," Dr. McNeill declared. In an editorial accompanying the study, Barry M. Popkin, Ph.D., of the University of North Carolina, called the findings "excellent" and "timely." "Obesity, heart disease, and cancer are acknowledged to be reaching epidemic levels across the globe, food prices are rapidly increasing, and looming crises exist related to energy, climate change, and water," he noted.
To prevent cancer and heart disease, he noted, nutritionists recommend limiting saturated fats to less than 10% of total daily calories. That would require higher-income countries to "cut their animal source food intake, shift to leaner meats, and shift to reduced-fat dairy products."
Dr. Popkin urged physicians to advise patients to consume small to moderate amounts of red and processed meat. The study was supported by the Intramural Research Program of the NIH and the National Cancer Institute. Neither the researchers nor the editorialists declared any conflicts of interest.
Primary source: Archives of Internal MedicineSource reference:
Sinha R, et al "Meat intake and mortality" Arch Intern Med 2009; 169(6): 562-71.
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