A vegetarian diet is associated with a substantially lower risk of developing five types of cancer, according to a landmark study published today in the British Journal of Cancer. The research, which analyzed data from over 1.8 million individuals tracked over many years, revealed significant reductions in the incidence of pancreatic, prostate, breast, kidney cancer, and multiple myeloma among vegetarians compared to meat-eaters.
The study found that vegetarians experienced a 21% lower risk of pancreatic cancer, a 12% lower risk of prostate cancer, and a 9% lower risk of breast cancer. Further analysis indicated a 28% reduction in kidney cancer risk and a 31% reduction in the risk of multiple myeloma, a cancer of plasma cells. These five cancers collectively account for approximately one-fifth of all cancer deaths in the United Kingdom, researchers noted.
Dr. Aurora Pérez-Cornago, the principal investigator of the study, formerly based at the University of Oxford, described the findings as “really good news for those who follow a vegetarian diet because they have a lower risk of five cancer types, some of which are particularly prevalent in the population.”
However, the research also identified potential drawbacks associated with vegetarian diets. Vegetarians exhibited nearly double the risk of squamous cell carcinoma, the most common form of oesophageal cancer, compared to meat-eaters. Researchers hypothesize this increased risk may be linked to deficiencies in key nutrients, such as B vitamins, commonly found in animal products.
The study also revealed a higher risk of certain cancers among vegans. Vegans demonstrated a 40% increased risk of bowel cancer compared to meat-eaters, potentially due to lower average calcium intake – 590mg per day, below the UK’s recommended daily allowance of 700mg – and other nutrient deficiencies.
The comprehensive analysis drew upon data from 1.64 million meat-eaters, 57,016 poultry eaters (excluding red meat), 42,910 pescatarians (fish eaters), 63,147 vegetarians, and 8,849 vegans, with an average follow-up period of 16 years. Researchers accounted for factors known to influence cancer risk, including body mass index and smoking habits.
The study, funded by the World Cancer Research Fund, investigated 17 different cancers, encompassing those affecting the gastrointestinal tract, lungs, reproductive system, urinary tract, and blood. No evidence suggested a lower risk of bowel cancer for vegetarians compared to meat-eaters, a finding researchers attribute to relatively low red and processed meat consumption within the study’s meat-eating cohort. Professor Tim Key, emeritus professor of epidemiology at the University of Oxford and a co-investigator, suggested that results might differ with a cohort exhibiting higher levels of meat consumption.
Pescatarians showed lower risks of breast and kidney cancers, as well as a reduced risk of bowel cancer. Poultry eaters were found to have a lower risk of prostate cancer.
Professor Jules Griffin, director of the Rowett Institute, University of Aberdeen, who was not involved in the research, acknowledged the study’s significance, stating that a comparison to a group adhering to the NHS Eatwell guidelines – which advocate for moderate meat and fish consumption – would provide a more complete understanding of optimal dietary patterns for cancer risk reduction.
Researchers emphasized the necessitate for further investigation to determine whether the observed benefits stem from avoiding meat consumption altogether or from specific characteristics of vegetarian diets. The long-term nature of the study, spanning the 1990s and 2000s, also means that dietary habits may have evolved since the initial data collection, with increased consumption of ultra-processed foods and the availability of nutrient-fortified vegan products like oat milk.
