Studies that look at people and their habits have linked vegetarian diets with a decreased risk of heart disease, diabetes, high blood pressure, obesity, and colon cancer. A review of studies looked at the effects of vegetarian diets among Seventh-Day Adventists, whose religious doctrine advises against eating animal flesh. The review found that Seventh-Day Adventists had less heart disease and fewer cases of some types of cancer than most people. For instance, vegetarians tended to have lower rates of prostate and colon cancer. On average, Seventh-Day Adventist males had serum cholesterol levels and blood pressures that were lower than average. And, their overall cancer death rate was about half that of the general population. The overall cancer death rate of females was also lower.
A study that looked at groups of people in Germany found the death rate for colon cancer was lower among moderate and strict vegetarians compared with that of the general population. The authors of this study also noted vegetarians tend to be more health conscious than average. In Great Britain, a 17-year study followed 11,000 vegetarians and health-conscious people. They concluded that eating fresh fruit every day was linked to a significant reduction in deaths from ischemic heart disease, stroke, and all causes of death combined. Another population study found men who ate a diet rich in grains, cereals, and nuts had a lower risk of prostate cancer.