Mortality among German vegetarians: first results after five years of follow-up.

A prospective study of vegetarians recruited from all regions of the Federal Republic of Germany, including West Berlin, was started in 1978 after a preparatory phase of two years in which the cohort was established. The mortality of the 1,904 study participants was evaluated after a follow-up of five years, comparing observed deaths with expected rates based on the national mortality statistics. Of the 858 men and 1,046 women, 89% had followed their diet for at least five years at study entry, the majority of them as strict vegetarians (1,163). By the end of 1983, only 82 persons had died, whereas 219 deaths were expected. In both sexes, the mortality was lowest from cardiovascular diseases [standardized mortality ratio (SMR) for ischemic heart disease about 20] and from cancer (SMR 58 for men, 54 for women). Deaths from diseases of the respiratory and digestive system were also reduced. For individual cancer sites the observed numbers were extremely small, but the risk of dying from lung cancer was significantly reduced; however, deaths from cancers of the colon and rectum, prostate, and breast were rare or even absent. More deaths than expected were observed from stomach, pancreatic, testicular, and brain cancers. An internal comparison of mortality between strict and moderate vegetarians (741) suggests a higher mortality from all causes and malignant neoplasms among strict vegetarians in both sexes, although not statistically significant, and a lower mortality from circulatory system diseases for males. The possible influence of selection factors (e.g., "healthy participant effect," socioeconomic level, and body weight) on the findings of a decreased mortality is discussed together with the role of diet.