According to the World Health Organization, about one-third of all cancers can be prevented by factors within your control, including diet.
For instance, eating legumes regularly may reduce your risk of colorectal cancer by about 9–18% (
Research also suggests that eating at least seven portions of fresh fruits and vegetables per day may lower your risk of dying from cancer by up to 15% (
Vegans generally eat considerably more legumes, fruit and vegetables than non-vegans. This may explain why a recent review of 96 studies found that vegans may benefit from a 15% lower risk of developing or dying from cancer (
Avoiding certain animal products may also help reduce the risk of prostate, breast and colon cancers.
That may be because vegan diets are devoid of smoked or processed meats and meats cooked at high temperatures, which are thought to promote certain types of cancers (
On the other hand, there is also evidence that dairy may help reduce the risk of other cancers, such as colorectal cancer. Therefore, it’s likely that avoiding dairy is not the factor that lowers vegans’ overall risk of cancer (
It’s important to note that these studies are observational in nature. They make it impossible to pinpoint the exact reason why vegans have a lower risk of cancer.
However, until researchers know more, it seems wise to focus on increasing the amount of fresh fruits, vegetables and legumes you eat each day while limiting your consumption of processed, smoked and overcooked meat.
Certain aspects of the vegan diet may offer protection against prostate, breast and colon cancers.