Breast Cancer in Vegetarians & Vegans

There’s a new report from Adventist Health Study-2 (AHS-2) comparing breast cancer incidence in vegetarians and vegans to non-vegetarians (1).

The study included 24,211 non-vegetarians, 3,748 vegans, 14,336 lacto-ovo vegetarians, 5,179 pesco-vegetarians, and 2,930 semi-vegetarians. Meat intake among non-vegetarians was quite low at less than a serving per day (54 g/day). Participants were followed for an average of 7.8 years (which isn’t very long for a cancer study).

All vegetarians combined had similar rates of breast cancer to non-vegetarians (0.97, 0.84-1.11), while vegans had a 22% lower risk that didn’t reach statistical significance (0.78, 0.58-1.05). After adjusting for body mass index, the reduced risk was 15% for vegans (0·86, 0·62-1·21), indicating that lower body weight could explain some of the lower risk for vegans.

The authors write, “In conclusion, participants in this cohort who follow a vegetarian dietary pattern overall did not experience a lower risk of [breast cancer] as compared with non-vegetarians. However, those adhering to a vegan dietary pattern showed consistently lower point estimates in various subgroups but these were not statistically significant. Numbers of cancers in vegans were relatively small, and these analyses should be repeated in the AHS-2 cohort after a longer follow-up to determine whether the same trends continue when power is greater.”

I have posted these results in the article Cancer, Vegetarianism, and Diet.


1. Penniecook-Sawyers JA, Jaceldo-Siegl K, Fan J, Beeson L, Knutsen S, Herring P, Fraser GE. Vegetarian dietary patterns and the risk of breast cancer in a low-risk population. Br J Nutr. 2016 Mar 18:1-8. • link

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