Cancer is among the leading causes of death worldwide. In 2018, there were 18.1 million new cases and 9.5 million cancer-related deaths worldwide. By 2040, the number of new cancer cases per year is expected to rise to 29.5 million and the number of cancer-related deaths to 16.4 million.
It has been hypothesized that vegetarian diets, which exclude consumption of all meat and fish, may be associated with a lower cancer risk. In addition to excluding red and processed meat, which are associated with an increased risk of colorectal cancer, vegetarians also generally consume higher amounts of plant foods such as fruits, vegetables, and whole grains compared to meat-eaters.
In a new study published in the journal BMC Medicine, researchers conducted a study to assess the associations of vegetarian and non-vegetarian diets with the risks of all cancer, colorectal cancer, postmenopausal breast cancer, and prostate cancer.
The researchers used participants from the UK Biobank, and included a total of 472,377 patients who were free from cancer at recruitment. The participants were categorized into 4 groups, regular meat-eaters (247,571), low meat-eaters (205,385), fish-eaters (10,696), and vegetarians (8,685) based on dietary questions completed at the moment of recruitment.
The participants were follow-up for 11.4 years on average, and 54,961 cases of cancers were identified, including colorectal, postmenopausal breast, and prostate cancers.
The researchers found that compared with regular meat-eaters, being a low meat-eater, fish-eater, or vegetarian were all associated with lower risk of all cancer, while being a low meat-eater was associated with a lower risk of colorectal cancer compared to regular meat-eaters.
Also, vegetarian postmenopausal women had a lower risk of breast cancer, and in men being a fish-eater or vegetarian was associated with a lower risk of prostate cancer.
The results are consistent with previous studies that suggest that meat intake can cause adverse effects to our health and increase the risk of cancer and other medical conditions. A 2% less risk was observed in low meat-eaters, 10% in fish-eaters, and 14% in vegetarians when compared to regular meat-eaters.
Watling, C.Z., Schmidt, J.A., Dunneram, Y. et al. Risk of cancer in regular and low meat-eaters, fish-eaters, and vegetarians: a prospective analysis of UK Biobank participants. BMC Med 20, 73 (2022). https://doi.org/10.1186/s12916-022-02256-w