An omega-3-rich diet may slow down prostate cancer

A new clinical study conducted by UCLA Health has uncovered a promising result: a diet low in omega-6 fats and rich in omega-3, supplemented with fish oil, can significantly slow the growth of prostate cancer in men following the strategy of active surveillance.

This approach, which involves regular monitoring of the tumour without immediate intervention, is often chosen by those with an early, low-risk form of the disease.

The results of the CAPFISH-3 study, published in the Journal of Clinical Oncology, represent an important step towards integrating nutrition into the clinical management of prostate cancer.

The aim of the study: to slow down cancer without drugs

Prostate cancer is one of the most common cancers among men, but it does not always require immediate treatment. In many cases, especially in the early stages, one opts for active surveillance, which consists of regular check-ups to monitor the evolution of the disease.

However, a proportion of men who choose this route end up having to resort to more invasive treatments within five years.

The UCLA team, led by Professor William Aronson, wondered whether modifying the diet could delay tumour progression, thus offering patients a simple and non-invasive way to gain valuable time before facing more aggressive therapies.

How the CAPFISH-3 study was conducted

The study involved 100 men with low- or medium-risk prostate cancer, all in active surveillance.

The participants were divided into two groups: one continued with their usual diet, while the other adopted a diet low in omega-6 (found in many refined vegetable oils and industrial foods) and rich in omega-3 (from oily fish and fish oil supplements). The diet was followed for one year, with the support of nutritionists who provided personalised advice.

The results: less tumour proliferation

The most significant result was a 15% reduction in the Ki-67 index in the group following the modified diet.

This index is a biomarker that measures the speed at which tumour cells multiply. A decrease is a sign that tumour growth has slowed down.

These data are particularly relevant because, until now, no other clinical study had shown such a direct impact of diet on prostate cancer progression. Other studies had suggested benefits from a diet rich in vegetables or a healthy lifestyle, but without statistically significant results on tumour growth.

The CAPFISH-3 study is distinguished by the use of an objective biomarker such as Ki-67. In the past, research such as the Prostate Cancer Prevention Trial had explored the effect of diet and supplements (such as lycopene or vitamin E), but with mixed or even negative results.

Another interesting study, conducted in Canada in 2022, had shown that a Mediterranean diet could improve the quality of life in prostate cancer patients, but showed no direct effect on cell proliferation.

CAPFISH-3, on the other hand, provides evidence that changing dietary fat intake can influence tumour behaviour.

Future perspectives: towards customised nutritional guidelines

The study results open the way to new possibilities in the management of prostate cancer. If confirmed by larger studies, these data could lead to the introduction of specific nutritional guidelines for patients in active surveillance. Furthermore, they could stimulate further research on the effect of other nutrients or food combinations.

Professor Aronson emphasised that “even small changes in diet can have a significant impact”, and that many patients are motivated to change their lifestyle if it can help them avoid invasive treatments.

The CAPFISH-3 study represents a breakthrough in the way we view the role of nutrition in the fight against prostate cancer. It is no longer just a question of eating healthy in a general sense, but of targeting the biological mechanisms of the disease.

A diet rich in omega-3 and low in omega-6 could, in the future, become a real nutritional therapy to slow down cancer and improve patients' quality of life.