• Posted February 16, 2023

Switch to Plant-Based Diet Could Boost Prostate Cancer Survival

Following a healthy plant-based diet after a diagnosis of prostate cancer may help prevent the disease from progressing or recurring, a new study suggests.

Men who ate a diet rich in fruits, vegetables and whole grains had a 52% lower risk of cancer progressing and a 53% lower risk of recurrence, compared with men who had the lowest amounts of plants in their diet, the researchers found.

"Progressing to advanced disease is one of many pivotal concerns among patients with prostate cancer, their family and caregivers and their physicians," said lead researcher Vivian Liu, a clinical research coordinator at the Osher Center for Integrative Health at the University of California, San Francisco.

"These findings may directly inform clinical care by providing diet recommendations as guidance for managing their health and reducing morbidity for the most common cancer facing U.S. men, in addition to having other positive health benefits for preventing other chronic diseases," Liu said.

A plant-based diet may have these benefits because fruits and vegetables contain antioxidants and anti-inflammatory components, as well as dietary fiber that improve glucose control and reduce inflammation, she explained.

Also, this diet reduces potentially harmful exposures to animal-based foods, such as hormones and heterocyclic amines created during high-temperature cooking, which have been linked to prostate cancer in particular, Liu said.

Diets high in animal protein may also increase insulin resistance, while milk and dairy may increase levels of the growth factor IGF1, which has been associated with prostate cancer risk, she noted.

For the study, Liu and her colleagues used data from a study that collected information on more than 2,000 men with prostate cancer.

Over a median of seven years, the researchers found that men who reported diets that included the highest amounts of plants had a lower risk of both progression and recurrence, compared with men who ate the lowest amounts of plants. This association did not vary by age, walking pace or the severity of cancer.

"Post-diagnostic healthful plant-based diets, including vegetables, fruits, legumes and whole grains, may be associated with a reduction in risk of prostate cancer progression and recurrence, adding to a list of other numerous health benefits including a reduction in diabetes, cardiovascular disease and overall mortality," Liu said.

The findings are to be presented Thursday at the 2023 American Society of Clinical Oncology (ASCO) Genitourinary Cancers Symposium, in San Francisco. Findings presented at medical meetings are considered preliminary until published in a peer-reviewed journal.

Dr. Anthony D'Amico, chief of the Division of Genitourinary Radiation Oncology at the Dana-Farber Cancer Institute in Boston, cautioned that although the findings are promising, they can't prove that a plant-based diet caused prostate cancer outcomes to improve, only that there is an association between the two.

Having said that, he added that there is biological evidence that plant-based diets are healthier and can boost the immune system.

"So, there's a biological rationale for it being able to slow the risk of progression of any cancer as a result of immune surveillance," D'Amico said. "The other side is people who eat a plant-based diet also tend to exercise, which has been shown to boost the immune system."

A healthy lifestyle also lowers the risk of cancer recurrence and progression because patients can tolerate treatments better, are more likely to get the full treatment and are more likely to be compliant, D'Amico said.

"I don't want to challenge these findings completely. I don't want to poo-poo it. It's not a bad thing to do. I just don't want people to think that it's proof," D'Amico said. "I would recommend that people take the entire picture into account, that is, they exercise, they don't smoke, they don't drink, they eat healthy, they reduce stress -- those things all can help."

More information

The American Cancer Society has more on prostate cancer.

SOURCES: Vivian Liu, clinical research coordinator, Osher Center for Integrative Health, University of California, San Francisco; Anthony D'Amico, MD, PhD, chief, Division of Genitourinary Radiation Oncology, Dana-Farber Cancer Institute, Boston; 2023 American Society of Clinical Oncology Genitourinary Cancers Symposium, San Francisco, Feb. 16-18, 2023