Dietary recommendations for people with a history of cancer are essentially the same as they are for anyone seeking to optimize their health and longevity — and offer similarly profound benefits in terms of risk reduction. Given the evidence on diet and cancer incidence and recurrence, the American Institute for Cancer Research, National Comprehensive Cancer Network and American Cancer Society all recommend people with a history of cancer consume a diet high in fruits and vegetables, whole grains, plant-based fats, nuts and legumes, with limited amounts of refined grains, added sugars, red and processed meats, and alcohol.
The impact of individual dietary factors, such as fat, fiber and meat, on recurrence of various types of cancer has been evaluated in studies with mixed or inconclusive results. Overall, diets rich in plant foods have a positive impact on health and quality of life after cancer treatment, due in part to their nutrient density and fiber, which also help promote a healthy weight. Research suggests a lower risk of cancer recurrence in people who eat a diet rich in fruits, vegetables and whole grains, with most dietary fat coming from nuts and olive oil, and low amounts of red and processed meats, refined grains and full-fat dairy.
Although many people with a history of breast cancer worry about the potential cancer-promoting effects of dairy or soy, evidence indicates that neither low-fat dairy nor soy is linked to increased risk of recurrence — and moderate consumption of minimally processed soy foods may even have a protective effect. Similar questions have been raised regarding the effect of phytoestrogens in soy or flax on prostate cancer recurrence. The best available evidence suggests consuming soy and flaxseed may have a protective benefit, but people with a history of prostate cancer should avoid consuming large amounts of flax oil.
Restrictive dietary regimens, such as The Gerson Therapy or macrobiotic diets, are often promoted to people with a history of cancer. However, there is no evidence that such approaches reduce the risk of recurrence any more than a prudent dietary pattern.
The American Cancer Society recommends working with a registered dietitian nutritionist during and after cancer treatment for individualized nutrition care. Research suggests working with an RDN is especially helpful for healthy weight management, particularly in individuals with past female reproductive cancers.