More omega-3 can reduce malignant cell growth in prostate cancer

Prostate cancer is widespread in the Western world. However, according to an American study published in the Journal of Clinical Oncology, dietary changes with more omega-3 fatty acids and fewer omega-6 fatty acids can reduce the development of prostate cancer cells after one year.

Prostate cancer is the most common cancer type among men in the Western world but is rare in Japan, China, and among Inuit populations. The global difference in incidence reveals that this type of cancer is a lifestyle disease. The risk of developing prostate cancer increases with age and correlates with the PSA level (Prostate-Specific Antigen) in the blood. Prostate cancer is classified into stages depending on how advanced the disease is. Many men diagnosed with a low-risk stage prefer monitoring over immediate treatment. However, within five years, approximately 50% of these men will experience disease progression to higher stages, requiring surgery or radiation therapy. Therefore, many of those who opt for monitoring want to know whether dietary changes can help counteract disease progression.
The new study, conducted at the University of California, aimed to investigate whether an increased intake of omega-3 from diet and fish oil supplements, combined with a reduced intake of omega-6, could slow the development of prostate cancer cells. This can be assessed by measuring cancer cells' Ki-67 index, a marker used to evaluate how aggressively a tumor grows. A high Ki-67 index indicates a poor prognosis.
The study included a group of men diagnosed with stage 1 or 2 prostate cancer. All participants were under monitoring and were divided into two groups. Over the course of a year, one group consumed less omega-6 and more omega-3 from their diet (including fish oil supplements). The other group served as a control group and made no dietary changes.
Based on biopsies, researchers observed that the group consuming more omega-3 and less omega-6 over a year experienced a decrease in the Ki-67 index of approximately 15%. Conversely, the Ki-67 index increased by 24% in the control group. This represents a significant statistical difference in the Ki-67 index and cancer progression between the two groups.
The researchers conclude that a diet with less omega-6 and more omega-3 from food and fish oil supplements can reduce the Ki-67 index, a biomarker of prostate cancer progression, metastasis, and mortality. The study aligns with a previous study published in Nutrients in which it was shown that prostate cells' omega-3 fatty acid content is inversely proportional to the risk of developing prostate cancer. This suggests that omega-3 intake also plays a crucial role in disease prevention.

Why Should There Be a Balance Between Omega-3 and Omega-6 Fatty Acids?

Omega-3 and omega-6 fatty acids are essential, meaning they must be obtained through diet. These fatty acids are found in cell membranes, where they participate in numerous metabolic processes of crucial importance to the immune system, inflammation regulation, circulation, activation of neuromechanisms, and many other functions. It is important to maintain the right balance between these two fatty acids. However, modern diets often contain excessive omega-6 from seed oils such as corn oil, sunflower oil, grapeseed oil, and safflower oil, as well as margarine, French fries, chips, ready meals, and junk food. At the same time, modern diets often lack sufficient omega-3 from fatty fish, including farmed fish that are fed unnatural diets. Fortunately, restoring the balance between omega-3 and omega-6 is relatively simple through minor dietary changes and high-quality fish oil supplements.

Other Relevant Dietary Recommendations

As mentioned, diet plays a significant role in prostate cancer development, and studies show that the disease is less common in populations that consume more fish and shellfish. In addition to omega-3 fatty acids, fish and shellfish contain selenium and zinc, which have other cancer-preventive mechanisms. However, it is often difficult to obtain sufficient selenium and zinc.

References:

William J. Aronson et al. High Omega-3, Low Omega-6-diæt With Fish Oil for Men With Prostate Cancer on Active Surveillance: The CAPFISH-3 Randomized Clinical trial. Journal of Clinical Oncology 2024.

University of California – Los Angeles Sciences. A low omega-6, omega-3 rich diet and fish oil may slow prostate cancer growth. ScienceDaily. December 2024

Hanane Moussa et al. Omega-3 Fatty Acids Survey in Men under Active Surveillance for Prostate Cancer: from Intake to Prostate Tissue Level. Nutrients 2019