A new large-scale study led by the University of Oxford has found that eating meat five times or less per week is associated with a lower overall risk of developing cancer. Moreover, eating only fish, or following a fully vegetarian or vegan diet could reduce cancer risks even more.
The researchers investigated the relationship between diet and cancer risk by analyzing UK Biobank data collected from 472,377 British adults between 2006 and 2010. The participants – aged between 40 and 70 years – had to report how often they ate meat or fish. 247,571 (52 percent) of them ate meat more than five times per week, 205,382 (44 percent) ate meat five or less times per week, 10,696 (two percent) ate fish but not meat, and 8,685 (less than 2 percent) were vegetarian or vegan. During the study period, 54,961 participants (12 percent) of the participants developed cancer.
After accounting for other factors such as diabetes status or sociodemographic, socioeconomic, and lifestyle factors, the scientists found that the overall cancer risk was two percent lower among people who ate meat less than five times per week, 10 percent lower for those who ate fish but not meat, and 14 percent lower for vegetarians and vegans, compared to those who ate meat five or more times per week.
In terms of specific types of cancer, the scientists found that low meat-eaters had lower risk of colorectal cancer, vegetarian women had a lower risk of postmenopausal breast cancer, and vegetarian or fish-eating men had a lower risk of prostate cancer.
While the reduced risk of colorectal cancer in low meat-eaters is consistent with previous findings, it is not yet clear if the other correlations reflect any causal relationships or are due to confounding factors. For instance, the lower risk of postmenopausal breast cancer in women could also be explained by their lower body mass index (BMI).
“It is not clear if the other associations are causal or a result of differences in detection between diet groups or unmeasured and residual confounding. Future research assessing cancer risk in cohorts with large number of vegetarians is needed to provide more precise estimates of the associations and to explore other possible mechanisms or explanations for the observed differences,” concluded the authors.
The study is published in the journal BMC Medicine.