One reason often cited for becoming a vegetarian of some sort is that such a lifestyle is somehow "healthier." And indeed, there have been studies linking vegetarianism to a lower risk of some types of breast cancer. Conversely, some studies have linked high consumption of meat to an increased risk of colorectal cancer.
Such results, however, beg the question of whether people who adhere to some sort of vegetarianism have a lower risk of dying from any cause. A new report in the American Journal of Clinical Nutrition doesn't support that decreased risk.
Dr. Paul N Appleby from the Department of Population Health, University of Oxford, United Kingdom and colleagues pooled data from two prospective studies of people who ate different types of diets in the UK.
Over half ate meat with some regularity (the most frequent being five or more times per week); some ate fish but no meat; and the rest were vegetarians of some type (some consumed milk and/or eggs); and vegans (those who ate no animal products, including milk and eggs). All individuals were between the ages of 20 and 89 years of age at the beginning of the study. One study ( the OVS cohort comprised of over 11,000 people) recruited participants between 1980 and 1984. The other study, the EPIC-Oxford cohort, recruited over 65,000 individuals between 1993 and 1999.
At baseline and after five, 10, and 15 years, surviving participants answered questions about the frequency of their meat consumption, and whether or not they ate fish, eggs, and dairy products. The investigators assessed the risk of 18 different possible causes of death. These ranged from malignant cancer, mental and behavioral disorders, and ischemic heart disease. They also calculated the risk of mortality from all causes, and assessed its link to the different types of dietary protocols.
Using the group that reported regular meat consumption as the control group, the investigators compared the risk of the various disease of the different diet groups. They found that on the whole, the differences in risk were small.
For example, the difference in risk of dying from ischemic heart disease ranged from a decrease of about 4 percent in those who ate meat infrequently to a decrease in risk of about 6 percent in those who reported eating fish. None of these differences was statistically significant. Even more interesting was the fact that overall, the risk of death from all causes was not statistically different across the diet groups, ranging from -1 percent in a combination group of vegetarians and vegans to -6 percent in those eating meat infrequently. Thus these data did not support the theory that vegetarianism decreases mortality.
The authors concluded "[O]ur results suggest that United Kingdom vegetarians and comparable nonvegetarians (including those who eat fish but not meat, and those who eat meat [less than] five times per week on average) have similar all-cause mortality."