The most extensive investigation to date into non-meat-based eating habits and their connection to cancer has revealed that following a vegetarian diet correlates with reduced chances of developing certain types of cancer, including breast, prostate, kidney, pancreatic cancers, and multiple myeloma. On the flip side, it shows an elevated risk for squamous cell carcinoma of the esophagus. This groundbreaking research was spearheaded by experts from the Cancer Epidemiology Unit at Oxford Population Health and appears in the British Journal of Cancer.
Well-designed vegetarian eating plans are widely regarded as beneficial for overall health, yet questions have lingered regarding their precise effects on the incidence of particular cancers. This uncertainty stems primarily from the fact that prior individual studies often lacked a sufficient number of vegetarian participants to draw firm conclusions. To overcome these limitations, the research team aggregated data from over 1.8 million individuals spanning three continents via the Cancer Risk in Vegetarians Consortium.
In their analysis, the scientists evaluated the occurrence of 17 distinct cancers among five distinct dietary categories: regular meat consumers, poultry consumers who avoid red and processed meats, pescatarians who include fish in their diets, vegetarians who incorporate dairy products and/or eggs, and strict vegans.
When pitted against those who eat meat regularly, individuals adhering to vegetarian diets demonstrated notably lower risks for several cancers, specifically:
- A 21% reduction in the risk of pancreatic cancer.
- A 9% decrease in breast cancer risk.
- A 12% drop in prostate cancer likelihood.
- A substantial 28% lower chance of kidney cancer.
- A 31% diminished risk for multiple myeloma.
That said, vegetarians faced almost twice the risk of developing squamous cell carcinoma of the esophagus compared to meat eaters.
For other cancer types, such as colorectal, stomach, liver, lung cancer among never-smokers, endometrial, ovarian, cancers of the mouth and pharynx, bladder cancer, non-Hodgkin lymphoma, leukemia, and esophageal adenocarcinoma, the study found no meaningful statistical variations in risk levels between vegetarians and meat eaters.
Tim Key, who holds the position of Emeritus Professor of Epidemiology at Oxford Population Health and served as a co-investigator on this project, commented, “Approximately 3 million people in the UK follow vegetarian diets, and global interest in vegetarianism continues to rise across various regions. Cancer remains one of the top causes of mortality globally, responsible for nearly one in every six deaths. Health guidelines emphasize dietary approaches rich in fruits, vegetables, and fiber-rich foods while steering clear of processed meats to help mitigate cancer risks. This research provides valuable insights into both the advantages and potential drawbacks linked to vegetarian eating patterns.”
In contrast, vegans exhibited a statistically significant increase in colorectal cancer risk relative to meat eaters. For the remaining cancers examined, no clear evidence emerged indicating differing risks for vegans compared to meat eaters. In cases of rarer cancers, the sample size of vegan participants was too limited to perform reliable analyses. Ongoing research will be essential to validate these observations within vegan communities.
Aurora Perez Cornago, the study’s lead investigator and previously an Associate Professor at Oxford Population Health, elaborated, “Vegetarians generally intake higher amounts of fruits, vegetables, and fiber compared to meat eaters, and they completely avoid processed meats, factors that likely contribute to decreased risks for certain cancers. The elevated risk of esophageal squamous cell carcinoma among vegetarians and colorectal cancer among vegans could be tied to reduced consumption of specific nutrients that are more prevalent in animal-derived products. More in-depth studies are required to pinpoint the exact mechanisms behind these observed cancer risk disparities.”
Pescatarians showed reduced risks for breast cancer, kidney cancer, and colorectal cancer. Meanwhile, those who primarily consume poultry, avoiding red and processed meats, had a lower incidence of prostate cancer.
Yashvee Dunneram, the primary author of the study and a former postdoctoral epidemiologist at Oxford Population Health, explained, “Within the 72,000 vegetarians and vegans participating in our research, the case numbers for certain cancers were relatively low, which somewhat constrains the reliability of those specific results. Additionally, nutrient consumption and the overall quality of diets can differ widely both within vegetarian groups and across different vegetarian communities. Our upcoming efforts will focus on gathering additional data on vegan eating habits and expanding data collection from diverse global regions.”
Dr. Helen Croker, Assistant Director of Research and Policy at World Cancer Research Fund International, observed that individuals seeking to reduce their meat consumption merit dependable evidence to guide their choices, and this study delivers the most thorough evidence available to date on vegetarian and other non-meat diets in relation to cancer risks. The findings indicate that non-meat diets are associated with lowered risks for specific cancers, although not universally across all types, underscoring key distinctions between various cancers and the influence of diverse dietary regimens.
“For optimal cancer prevention, we recommend constructing meals centered on whole grains, pulses, fruits, and vegetables, while eliminating processed meats and moderating intake of red meat,” she advised.
