Diet rich in omega 3 foods may slow progression in early stage prostate cancer

CANCER DIGEST – Dec. 14, 2024 – Men with prostate cancer who have chosen "watchful waiting" or surveillance might be able to extend the time before more aggressive treatment is needed by increasing omega-3 fats in their diets, a new study shows.

Led by William Aronson, MD of the David Geffen School of Medicine at the University of California Los Angeles researchers conducted a clinical trial involving 100 men with low-risk prostate cancer who had chosen active surveillance over immediate treatment. The results of the one-year study appear in the Dec. 13, 2024 Journal of Clinical Oncology.

In the trial conducted by phone, telehealth, or in person involved counseling for half the men on ways to increase the amount of omega-3 fats in their diet while decreasing the amount of omega-6 fats. The other half or control group continued standard monitoring with no additional dietary counseling.

Omega fats are natural lipids that are necessary for healthy nutrition. Both are polyunsaturated fats, which refers to their chemical structure. A bond in chemistry is the force that holds atoms together to form a molecule. Unsaturated refers to the double bonds of the molecules, thus polyunsaturated means the compound has many double bonds. omega-3 refers to the position of the last double bond which occurs 3 carbon atoms from the "omega" or tail end of the molecular chain. Likewise omega-6 is so named because its final double bond occurs 6 carbon atoms from the end of the molecular chain.

In general omega-3 fatty acids are anti-inflammatory nutrients that play a role in brain, nerve and eye development in infants and have benefits in adults for heart, brain and metabolism. Omega-6 fatty acids, although an essential nutrient, tend to be pro-inflammatory and play a role in the immune system. The key is to get the right ratio of omega-6 to omega-3 in the diet. A typical Western diet may contain a ratio has high as 15 to 1 omega-6 to omega-3.

In the trial, called CAPFISH, patients in the treatment group followed a diet of low omega-6 and high omega-3 foods, such as low-fat salad dressings with olive oil and lemon, fish such as salmon and avoidance of cookies, chips, mayonnaise and fried foods. In addition they receive fish oil supplements. The goal was to create a favorable balance between omega-6 and omega-3. 

The researchers also tracked the changes using a biomarker called the Ki-67 index, which  tracks how fast cancer cells are multiplying. In addition, same-site biopsies were taken from both groups at the beginning of the study and again after one year.

After a year, the men in the high omega-3, lower omega-6 group had a 15 percent decrease in their Ki-67 index, while the control group saw a 24 percent increase in the Ki-67 index. In other words the rate of increase in cancer cells was significantly lower in the omega-3 group compared to the control group.

“This significant difference suggests that the dietary changes may help slow cancer growth, potentially delaying or even preventing the need for more aggressive treatments,” said Aronson,  in a press release.

The researchers warn that additional research is needed to confirm whether the long-term benefits of raising omega-3 and lowering omega-6 in these patients includes slowing cancer progression, improving treatment outcomes and increasing overall survival.

Sources: UCLA Geffen School of Medicine press release and the Journal of Clinical Oncology