From futura-sciences.com
For decades, vegetarian and vegan diets were billed as cancer shields, but small studies couldn't prove it either way. A February 2026 British Journal of Cancer study tracked 1.8 million people across three continents and settled that: diet changes cancer odds, just not how most hoped.
Vegetarian risk profile
Compared with meat eaters, vegetarians showed meaningfully lower risks across five cancer types. Their risk of multiple myeloma, a blood cancer, was 31% lower. Kidney cancer risk was 28% lower, pancreatic cancer 21% lower, prostate cancer 12% lower, and breast cancer 9% lower. Those reductions held after adjusting for weight, smoking, alcohol, and other diet confounders.
Against those benefits, one finding stood out sharply. Vegetarians had nearly double the risk of squamous cell carcinoma of the esophagus, the most common form of esophageal cancer, compared with meat eaters. The researchers believe this may relate to lower intakes of nutrients concentrated in animal foods, particularly riboflavin and zinc. That association held across sensitivity analyses. It didn’t weaken when researchers excluded early follow-up years, ruling out reverse causation.
Pescatarians vs. vegans
Pescatarians, people who eat fish but no meat, showed lower risks of colorectal, breast, and kidney cancers relative to meat eaters. People who ate poultry but avoided red and processed meat had a lower risk of prostate cancer. Both groups showed a cleaner risk profile than either full vegetarians or vegans across the cancers studied.
Vegans presented more complications: their risk of colorectal cancer was 40% higher than meat eaters, a striking finding for a group that consumed no alcohol and had the highest fibre intake of any diet group, both factors normally associated with lower bowel cancer risk. The researchers suggest low calcium intake is the most likely explanation. Vegans consumed no dairy, and across every cohort with nutrient data, they had the lowest calcium intake of any group, well below the UK adult reference level of 700 milligrams per day. The World Cancer Research Fund has concluded that dairy and calcium supplements probably protect against colorectal cancer.
The authors are careful to note the vegan finding rests on just 93 colorectal cancer cases across seven studies, which limits confidence in the result. Further research, particularly with larger vegan populations, is needed before strong conclusions can be drawn.
Fig. 1: Pooled hazard ratios for cancers of the gastrointestinal tract in poultry eaters, pescatarians, vegetarians, and vegans, relative to meat eaters.
What the researchers say
Aurora Perez-Cornago, principal investigator, explained the vegetarian benefits. She pointed to higher fruit, vegetable, and fibre intake and no processed meat. “The higher risk of oesophageal squamous cell carcinoma in vegetarians and bowel cancer in vegans may relate to lower intakes of certain nutrients more abundant in animal foods,” she said. “Additional research is needed to understand what is driving the differences in cancer risk found in our study.”
Tim Key, Emeritus Professor of Epidemiology at Oxford Population Health and co-investigator, put the findings in broader context.
“Cancer is a leading cause of death worldwide, accounting for nearly one in six deaths,” he said. “Our study helps to shed light on the benefits and risks associated with vegetarian diets.”
Fig. 2: Pooled hazard ratios for cancers of the reproductive system in poultry eaters, pescatarians, vegetarians, and vegans, relative to meat eaters.
Why the results need careful reading
The study followed more than 1.8 million participants for a median of 16 years. It tracked 220,000 incident cancers across 17 cancer types in cohorts spanning the UK, US, Taiwan, and India. That scale gave it statistical power that previous studies lacked. Even so, the authors stress that vegetarian and vegan diets vary enormously across populations and individuals. Excluding meat does not guarantee a healthy diet — refined carbohydrates, ultra-processed foods, and nutritional gaps can all feature in plant-based eating patterns.
Residual confounding also cannot be ruled out. Across the cohorts, vegetarians tended to smoke less, drink less alcohol, and exercise more than meat eaters. The researchers adjusted for all of these factors, but unmeasured differences, family history of cancer, screening behaviour, cooking methods, may still have shaped some findings.
Fig. 3: Pooled hazard ratios for cancers of the urinary tract and blood in poultry eaters, pescatarians, vegetarians, and vegans, relative to meat eaters.
What the study does establish, more clearly than any previous research, is that the relationship between plant-based diets and cancer risk is not straightforward. Some cancers appear less likely, others more so, and the pattern shifts depending on exactly which foods are included or excluded.
For the UK’s three million vegetarians and tens of millions more worldwide, that distinction informs daily choices: what to plate, what to supplement, how to screen. Small shifts in risk add up over decades.
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