Vegetarians and Cancer Risk: Key Findings from a Study

A significant study has found that vegetarians have notably lower risks of developing five cancer types. This landmark research, encompassing data from over 1.8 million individuals tracked over many years, revealed that vegetarians experience a 21% decreased risk of pancreatic cancer, a 12% lower risk for prostate cancer, and a 9% reduced risk for breast cancer when compared to those who eat meat. Collectively, these cancers are responsible for about 20% of cancer-related deaths in the UK.

In addition, vegetarians showed a 28% lowered risk of kidney cancer and a 31% decrease in the risk of multiple myeloma, as noted in the British Journal of Cancer.

Dr. Aurora Pérez-Cornago, who headed the research while at the University of Oxford, remarked, “This study is reassuring for those on a vegetarian diet since they have a lower likelihood of five types of cancer, some of which are quite common.”

However, it’s worth noting that vegetarians appear to have nearly double the risk of squamous cell carcinoma of the esophagus compared to meat eaters. Researchers hypothesized that this might be linked to possible deficiencies in essential nutrients, like B vitamins, among vegetarians.

Interestingly, vegans were found to have a 40% greater risk of bowel cancer compared to their meat-eating counterparts. This could be attributed to their lower average calcium intake—590mg daily versus the UK’s 700mg recommendation—and possible deficiencies in other nutrients.

The researchers emphasized the need for further investigation to determine if meat consumption itself is the issue or if specific components of vegetarian diets contribute to the reduced cancer risks. The answer, they suggested, may vary with different types of cancers.

(“It seems to me that the meat itself might be the bigger factor,” shared Prof. Tim Key, an emeritus professor of epidemiology at the University of Oxford and co-investigator, although this perspective hasn’t been explored thoroughly.)

While there’s already an established connection between red and processed meats and bowel cancer risk, identifying reliable data on less common cancer types has been a challenge due to the limited number of vegetarians and vegans in previous studies.

To address this gap, the current study utilized data sourced from various global diet and health studies. This enabled the researchers to examine around 1.64 million meat eaters, along with groups that included 57,016 poultry eaters, 42,910 pescatarians, 63,147 vegetarians, and 8,849 vegans, all followed on average for 16 years. They also accounted for variables that might affect cancer risk, such as body mass index and smoking habits.

Funded by the World Cancer Research Fund, the study explored 17 different cancers across various systems, including gastrointestinal, lung, reproductive, urinary tract, and blood cancers.

Interestingly, there was no evidence that vegetarians had a reduced risk of bowel cancer compared to meat eaters. This discrepancy may stem from the relatively low intake of red and processed meat within the study group, and Key remarked that the findings don’t contradict previous data linking red and processed meats to bowel cancer.

(“If more people with high meat consumption had been included in the meat-eating group, the results could have differed,” he added.)

Pescatarians showed lower risks for breast and kidney cancers and also had a reduced risk for bowel cancer, while poultry eaters had a lower risk for prostate cancer.

The participants were followed for an average of 16 years, a timeframe that allowed for effective cancer tracking but also means that dietary habits may have changed since the recruitment phase in the 1990s and 2000s. For example, there’s been a significant rise in the consumption of ultra-processed foods, and modern vegan products like oat milk are often fortified with important nutrients.

Prof. Jules Griffin, from the Rowett Institute at the University of Aberdeen and not involved in the study, found the research compelling. However, he noted that it lacked a comparison group based on NHS Eatwell guidelines, which suggest moderate meat and fish consumption while still providing essential nutrients. This could potentially represent an optimal diet for reducing diet-related cancer risks in the population.