1. Fruit, Vegetables, And Colorectal Cancer Risk: The European Prospective Investigation Into Cancer And Nutrition
This was the EPIC study (10 European countries), 452,755 men and women completed a dietary questionnaire in 1992–2000 and were followed for cancer incidence and mortality until 2006.
"The association between fruit and vegetable consumption and colorectal cancer risk was inverse in never and former smokers, but positive in current smokers."2. Cancer Incidence In Vegetarians: Results From The European Prospective Investigation Into Cancer And Nutrition (EPIC-Oxford)
This was an arm of the EPIC study (only the United Kingdom), 63,550 men and women recruited throughout the 1990s.
"The overall cancer incidence rates of both the vegetarians and the nonvegetarians in this study are low compared with national rates. Within the study, the incidence of all cancers combined was lower among vegetarians than among meat eaters, but the incidence of colorectal cancer was higher in vegetarians than in meat eaters."3. Vegetarian Diets: What Do We Know Of Their Effects On Common Chronic Diseases?
This was a review of this issues' findings.
"A number of studies have evaluated the health of vegetarians. Others have studied the health effects of foods that are preferred or avoided by vegetarians. The purpose of this review is to look critically at the evidence on the health effects of vegetarian diets and to seek possible explanations where results appear to conflict. There is convincing evidence that vegetarians have lower rates of coronary heart disease, largely explained by low LDL cholesterol, probable lower rates of hypertension and diabetes mellitus, and lower prevalence of obesity. Overall, their cancer rates appear to be moderately lower than others living in the same communities, and life expectancy appears to be greater. However, results for specific cancers are much less convincing and require more study. There is evidence that risk of colorectal cancer is lower in vegetarians and in those who eat less meat; however, results from British vegetarians presently disagree, and this needs explanation. It is probable that using the label "vegetarian" as a dietary category is too broad and that our understanding will be served well by dividing vegetarians into more descriptive subtypes. Although vegetarian diets are healthful and are associated with lower risk of several chronic diseases, different types of vegetarians may not experience the same effects on health."
So, the first study found that fruit and vegetable consumption was protective against colon cancer, except if you smoked. Then, oddly, eating fruit&veg increased your risk for colon cancer.
The second study found that vegetarianism was protective against all cancers, except colon cancer. In which case, not eating meat seemed to increase risk for colon cancer.
The last study, or review, reiterated previously documented benefits of vegetarianism and, as a way of explanation for the UK study in number 2 above, proposed that some vegetarian diets are better than others.
The photo I used for this post is exemplary of this last point. It could be a photo of a vegetarian meal (using vegetable-based meat analogs like tofurkey or fake bacon: "facon"), or a photo of a non-vegetarian meal with meat.