The American Cancer Society and the American Institute for Cancer Research both estimate that more than 30 percent of cancer can be prevented through healthy diet, physical activity, and maintaining a healthy weight. Smoking also accountsfor over 30 percent of cancers. This means that through appropriate lifestyle choices, more than 50 percent of cancers and cancer-related deaths could be avoided.
Diet in and of itself plays an important role in cancer prevention. Though the association between diet and cancer prevention is still not definitive, recent evidence suggests that diet may modify the risk of many cancers, including gastric, colorectal, breast, prostate, and lung cancers. For example, intake of dietary fiber and high consumption of fruit, vegetables, and fish has been associated with reduced risk of a number of cancers. Some population studies also demonstrate that vegetarianism is associated with lower risk of overall cancer and female-specific cancers. On the other hand, red and processed meat,dairy, alcohol, and saturated fat increase the risk of certain cancers.