Increasing consumption of both processed and unprocessed red meat was associated with a greater risk of dying during the study period, data from two large, prospective studies showed.Through up to 28 years of follow-up, each additional serving of red meat per day was associated with a relative 13% to 20% increased risk of all-cause mortality, with the higher risk attributed to processed meats, according to Frank Hu, MD, PhD, of the Harvard School of Public Health in Boston, and colleagues.It was estimated that 9.3% of the deaths in men and 7.6% of the deaths in women could have been prevented by consuming less than half of a serving of red meat (42 grams) per day, roughly equivalent to about one hot dog, the researchers reported online in Archives of Internal Medicine.However, 77.2% of men and 90.4% of women consumed more than that during the studies.Hu and colleagues examined data from the Health Professionals Follow-Up Study, which tracked men ages 40 to 75 at baseline from 1986 to 2008, and from the Nurses' Health Study, which followed women ages 30 to 55 at baseline from 1980 to 2008.The current analysis included 37,698 men and 83,644 women, all of whom were free from cardiovascular disease and cancer at baseline.Diet was assessed at baseline and every four years using a food frequency questionnaire. Unprocessed red meat included beef, pork, lamb, or hamburger and processed red meat included bacon, hot dogs, sausage, salami, and bologna.During follow-up, the amount of red meat eaten declined for both men and women.There were 23,926 deaths, including 5,910 from cardiovascular disease and 9,464 from cancer.Consistent with the analysis of all-cause mortality, each additional serving of red meat per day was associated with a greater risk of cardiovascular mortality (HRs 1.18 for unprocessed products and 1.21 for processed products) and cancer mortality (HRs 1.10 and 1.16).That was after adjustment for several potential confounders, including age, body mass index, alcohol consumption, physical activity levels, smoking status, race, menopausal status and hormone use in women, family history of diabetes, MI, or cancer, personal history of diabetes, hypertension, or hypercholesterolemia, and intakes of total energy, whole grains, fruits, and vegetables.Additional adjustment for other foods or nutrients yielded similar findings. Adjustment for saturated fat, cholesterol, and heme iron weakened the relationships with cardiovascular mortality slightly, although they remained statistically significant.The researchers estimated that substituting one serving per day of various other foods -- like fish, poultry, nuts, legumes, low-fat dairy, and whole grains -- for red meat was associated with a 7% to 19% lower risk of dying during follow-up.In an accompanying commentary Dean Ornish, MD, of the University of California San Francisco, noted that "plant-based foods are rich in phytochemicals, bioflavonoids, and other substances that are protective.""In other words," he wrote, "what we include in our diet is as important as what we exclude, so substituting healthier foods for red meat provides a double benefit to our health."Hu and colleagues said that the saturated fat, cholesterol, heme iron, sodium, and nitrites in red meat might explain some of the risk of cardiovascular death, and that some compounds either found in red meat or created by high-temperature cooking -- including nitrosamines, nitrosamides, polycyclic aromatic hydrocarbons, and heterocyclic amines -- are potential carcinogens and might explain some of the risk of cancer death.They acknowledged that the study was limited by potential errors in measuring red meat intake and by the uncertain generalizability of the findings outside of the study population, which was predominantly non-Hispanic white health professionals.
