We often hear that a plant-based diet is a straightforward recipe for a healthier life. But by tracking more than 1.8 million people over an average of 16 years, scientists have uncovered a much more complex reality.

When it comes to cancer, up meat creates a distinct biological trade-off, acting as a powerful shield against five types of cancers while simultaneously exposing the body to unexpected new risks.

The research, funded by the World Cancer Research Fund and published in the British Journal of Cancer, pooled data from nine major cohorts across the globe. Researchers analyzed 17 different cancers, identifying over 220,000 cases. The researchers thoroughly adjusted for physical and lifestyle differences like body mass index.

The good news for vegetarians is significant. Compared to meat-eaters, those on a plant-based diet saw:

• Kidney cancer rates drop by 28%.
• Multiple myeloma risk fall by 31%.
• Pancreatic cancer chances plummet by 21%.
• Prostate and breast cancer risks also saw notable declines.

“This study is really good news for those who follow a vegetarian diet because they have a lower risk of five cancer types, some of which are very prevalent in the population,” said Dr. Aurora Pérez-Cornago, the study’s principal investigator, according to The Guardian.

Dr. Pérez-Cornagonotes that metabolic shifts, like lower levels of specific proteins, likely drive these protections.

However, the data revealed a darker side. Vegetarians faced nearly double the risk of developing squamous cell carcinoma, a type of esophageal cancer. Scientists suspect this might stem from deficiencies in essential micronutrients that animal products usually provide.

The most startling finding involved vegans, who showed a 40% higher risk of bowel cancer. But there’s a catch: the number of vegans in the study was relatively small.

This “spike” might be a result of low calcium intake—vegans in the study averaged 590mg daily, well below the recommended 700mg.

It’s also worth noting that the “meat-eaters” in this study weren’t exactly living on steak alone. Most ate modest amounts of meat. Furthermore, the data comes from people tracked since the 1990s. Today, the landscape has changed; we have more ultra-processed “fake meats” but also better-fortified vegan staples.

“It could be that if we had had more people with very high intakes of meat in the meat-eating group, the results could have been different,” added Prof. Tim Key, a co-investigator at the University of Oxford.

The research broke down participants into five groups, tracking 1.65 million meat eaters, 57,016 poultry eaters, 42,910 pescatarians, 63,147 vegetarians, and 8,849 vegans.

These middle-ground diets offered notable protections. Pescatarians had lower risks of breast, kidney, and bowel cancers. Meanwhile, poultry eaters experienced a lower risk of prostate cancer. Scientists urge caution when interpreting the vegan data, as the higher bowel cancer risk was based on a small sample of vegans.

“Among the 72,000 vegetarians and vegans included in our study, the numbers of cases for some cancers were small, which limits the certainty of some findings,” Yashvee Dunneram, the study’s first author, emphasized in a statement.

So, where does this leave your dinner plate?

It’s tempting to want a “good vs. evil” narrative when it comes to food. We want a simple list of “safe” and “dangerous” ingredients. But as this massive data set proves, biology doesn’t do simple.

The results reinforce a broader consensus on cancer prevention: health depends on the entire dietary pattern, not just the absence of meat. Public health guidelines consistently advise building meals around whole grains, fruits, and vegetables, while limiting red and processed meats. For those shifting toward plant-based eating, the objective is to capture these broad protective benefits while carefully managing the nutritional gaps left behind by animal products.