Many people choose vegetarian diets to improve their health, protect the environment, or for ethical reasons. Fruits, vegetables, grains, beans, and nuts are often seen as healthy foods, and diets built around them are widely recommended.
However, scientists have long debated how avoiding meat affects the risk of different types of cancer. Some studies suggested vegetarians might have lower risks, while others found little difference. One reason for the uncertainty is that vegetarians make up a small portion of the population, making it hard to gather enough data for reliable results.
A new large international study led by researchers at Oxford Population Health has now provided the clearest picture so far. The scientists combined information from more than 1.8 million people across three continents.
By pooling such a huge amount of data, they were able to compare cancer risks among people with different eating habits, including meat eaters, people who eat poultry but not red meat, people who eat fish but no meat, vegetarians who eat dairy or eggs, and vegans who avoid all animal products.
The results showed that vegetarian diets were linked to lower risks of several types of cancer. Vegetarians had lower chances of developing pancreatic, breast, prostate, and kidney cancers, as well as multiple myeloma, a cancer of the blood cells.
Researchers believe this may be partly because vegetarian diets often contain more fiber, vitamins, and protective plant compounds, while avoiding processed meat, which has been linked to cancer.
However, the study also revealed a surprising finding. Vegetarians had a higher risk of a rare cancer called squamous cell carcinoma of the esophagus, which affects the tube that carries food from the mouth to the stomach.
Scientists are not yet sure why this risk was higher, but they suspect it could be related to differences in certain nutrients that are more common in animal-based foods. More research will be needed to understand this connection.
The study found mixed results for people following other non-meat diets as well. Vegans, who avoid all animal products, had a higher risk of colorectal cancer compared with meat eaters, although no clear differences were seen for most other cancers.
People who ate fish but not meat showed lower risks of breast, kidney, and bowel cancers. Those who ate poultry but avoided red meat had a lower risk of prostate cancer.
Importantly, the researchers emphasized that diet quality matters. Not all vegetarian diets are the same. Some people may eat mostly whole plant foods, while others rely on highly processed products.
Nutrient intake can vary widely, which may influence health outcomes. In addition, the number of vegetarian and vegan participants with certain rare cancers was still small, which means some results are less certain.
Cancer remains one of the leading causes of death worldwide, and experts continue to search for ways to reduce risk through lifestyle changes. Health organizations generally recommend diets rich in whole grains, beans, fruits, and vegetables, while limiting processed meat and reducing red meat consumption.
This study supports the idea that plant-based eating can offer protection against some cancers, but it also shows that no single diet guarantees complete protection.
For individuals thinking about changing their eating habits, the findings suggest that balanced nutrition is key. Ensuring adequate intake of essential nutrients, whether from plant or animal sources, is important for long-term health.
Future research will help clarify how specific foods and nutrients influence cancer risk and how people can design diets that provide the greatest benefits.
Overall, the study provides valuable evidence to guide personal choices and public health advice. While vegetarian diets appear to lower the risk of some cancers, they may increase the risk of others, highlighting the complexity of the relationship between diet and disease.
If you care about cancer, please read studies that artificial sweeteners are linked to higher cancer risk, and how drinking milk affects risks of heart disease and cancer.
For more health information, please see recent studies about the best time to take vitamins to prevent heart disease, and results showing vitamin D supplements strongly reduces cancer death.
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