How a diet rich with vegetables and fruits helped prostate cancer survivors: study

A new study from California researchers has found that a plant-based diet can be a powerful tool to reduce the progression of prostate cancer and the chances the illness will return.

“The main takeaway is: the more plants, the better. And just do the best you can with it, every bit helps,” said Vivian Liu, a clinical research co-ordinator at the Osher Center for Integrative Health at the University of California, San Francisco, in a phone call with CTVNews.ca Thursday.

Liu, who is the lead author of the study that she is presenting at a conference on cancer Thursday, said this is the only study to her knowledge that looks at outcomes of this kind of diet in prostate cancer survivors, as opposed to other research that has looked at diet and the risk of developing cancer.

“We’re hoping that these findings can strictly inform clinical care where providers can provide diet recommendations and guidance for managing their health,” she said.

HOW A PLANT-BASED DIET HELPED CANCER SURVIVORS

According to the Canadian Cancer Society, prostate cancer is the most common form of the illness among men, if non-melanoma skin cancers are excluded. It’s also the third leading cause of death from cancer in men in Canada.

In 2022, the society predicted that about 24,600 men would be diagnosed with prostate cancer and another 4,600 would die from it that year.

Liu and her co-authors looked at 2,038 men diagnosed with prostate cancer who were enrolled in the Cancer of the Prostate Strategic Urologic Research Endeavor, a larger study of 15,000 men across the U.S. that began in 1999.

The researchers were able to examine the diets of the 2,038 men as they had completed a food frequency questionnaire. The researchers used modelling to understand whether there was a connection between diet and disease progression, including examining other factors such asage, stage of cancer and walking pace.

The patients who reported diets with the most amount of plants incorporated had a 52 per cent lower risk of disease progression and a 53 per cent lower chance of cancer recurrence, compared to participants whose diets contained the least amount of plants. The plant-based diet was also particularly effective in older men over 65.

Out of the pool of men, 204 saw their cancer progress, which is close to 11 per cent of the participants.

Fruits and vegetables contain antioxidants and anti-inflammatory components, and contain dietary fibre, said Liu.

“So these can improve glucose control, as well as reduce inflammation,” she said. “The second thing is that they can also potentially reduce harmful exposure from animal-based foods such as hormones or heterocyclic amines, which are created during high-temperature cooking,” she said. Heterocyclic amines are chemical compounds that are carcinogenic.

A diet high in animal protein could increase insulin resistance and insulin levels, and dairy could increase levels of IGF1, short for Insulin-like growth factor 1, said Liu. IGF1 is a hormone that research has found could increase the risk for developing several types of cancer if it’s found in higher levels in the blood.

VEGGIES, FRUIT HELPFUL TO COMBAT OTHER CANCERS

Other recent studies have shown the health benefits of a plant-based diet when it comes to tackling cancer. One U.S. study published in March 2022 looked at the health of more than 47,000 men, and found that a plant-based diet was associated with a lower risk in developing prostate cancer, particularly for men over age 65.

Another large study published in November in the journal BMC medicine found that a plant-based diet lowered the chances of developing bowel cancer in men by 22 per cent. However, that link was not found in women.

Overall, Liu says she hopes this study sparks more research and that patients can be empowered with more information about how to make decisions around their health, and health-care providers can use the research as a support tool.

“This is something that men are able to do by themselves or with support…they have a shopping list with them, it’s very doable, to be able to go to a grocery store and find food that is helpful and can increase quality of life,” she said