OXFORD, UNITED KINGDOM— A study in the United Kingdom found participants who ate meat less than five times per week, participants who ate fish but not meat and vegetarians all had a lower risk of all cancers when compared to participants who ate meat more than five times per week. The study conducted by researchers from Oxford University appeared Feb. 24 in BMC Medicine.

The study involved 472,377 participants from the UK Biobank study using National Health Service records. They were free from cancer at recruitment. Regular meat-eaters numbering 247,571 ate meat five or more times per week. Low meat-eaters numbering 203,385 ate meat less than five times per week. Fish-eaters numbering 10,696 never ate red meat, processed meat or poultry but ate oily and/or non-oily fish. Vegetarians numbering 8,685 never ate meat or fish.

After an average of 11.4 years, 54,961 incidents of cancer were identified. When compared to high meat-eaters, low meat-eaters were associated with a 2% lower risk of all cancer, fish-eaters had a 10% lower risk of all cancer, and vegetarians had a 14% lower risk.

Low meat-eaters had a 9% lower risk of colorectal cancer when compared to high meat-eaters. Vegetarian postmenopausal women had an 18% lower risk of breast cancer when compared with high meat-eaters who were post-menopausal women. Those findings may be explained by vegetarian women having a lower body mass index (BMI).

Among all participants, the mean BMI was 25.7 for vegetarians, 25.3 for fish-eaters, 27 for low-meat eaters and 27.9 for high meat-eaters. The percentage of participants who said they did not smoke was 64% for vegetarians, 56.8% for fish-eaters, 55.7% for low meat-eaters and 43.5% for high meat-eaters. The percentage of participants with diabetes was 5.4% for vegetarians, 2.7% for fish-eaters, 5.2% for low meat-eaters and 6.3% for high meat-eaters.

“In conclusion, this study found that being a low meat-eater, fish-eater or vegetarian was associated with a lower risk of all cancer, which may be a result of dietary factors and/or non-dietary differences in lifestyle such as smoking,” the researchers said. “Low meat-eaters had a lower risk of colorectal cancer, vegetarian women had a lower risk of postmenopausal breast cancer, and men who were vegetarians or fish-eaters had a lower risk of prostate cancer. BMI was found to potentially mediate or confound the association between vegetarian diets and postmenopausal breast cancer.”