Can Fish Oil Fight the Side Effects of Prostate Cancer Treatment?
"New research explores how omega-3s could help men manage metabolic changes from testosterone-lowering therapies."
Prostate cancer is a major health concern, and treatments that lower testosterone, while effective against the cancer, can trigger a range of metabolic problems. These include insulin resistance, increased cholesterol, weight gain, and cardiovascular issues – basically, a cluster of symptoms known as metabolic syndrome.
This metabolic syndrome not only diminishes overall well-being but can also increase the risk of developing diabetes and heart disease. It’s a significant challenge for men undergoing prostate cancer treatment, highlighting the need for strategies to mitigate these side effects.
Now, new research is exploring whether omega-3 fatty acids, found in fish oil, can help counteract these metabolic changes. The study investigates the potential of EPA/DHA ethyl esters (Omacor) to alleviate metabolic syndrome in rats experiencing testosterone deficiency, offering hope for improving the quality of life for men undergoing similar treatments.
Evidence Still Developing
Prescribing fish oil to prevent metastases or reduce the likelihood of developing prostate cancer remains open for discussion. A July 21, 2025 Frontiers report notes that studies of omega-3 fatty acids and prostate cancer have produced inconsistent findings and that large-scale longitudinal dose-response data remain limited. A search of ClinicalTrials.gov identified four ongoing trials involving omega-3, fish oil, and prostate cancer in men at varying disease stages.
Clinical Testing Underway
One planned exploratory analysis included 130 patients with prostate cancer grade group 2 or greater in randomized controlled trial NCT02333435. The trial examined long-chain omega-3 supplementation in relation to biological and pathological outcomes at radical prostatectomy. Another study focused on men with prostate cancer receiving active surveillance and tested whether a high-omega-3, low-omega-6 diet with fish oil capsules reduced Ki-67 proliferation in prostate biopsies over one year, showing that these approaches remain under investigation rather than established treatment.
Decades of Investigation
Research into omega-3 fatty acids and cancer has continued for several decades. A 2022 review reported that its authors had previously examined the field's multitargeted cancer mechanisms in 2008, while hundreds of new clinical trials were being conducted to evaluate omega-3 polyunsaturated fatty acids in cancer therapy. Earlier work also reviewed fish oil and relevant omega-3 fatty acids, including initial investigations into prostate cancer prevention and treatment.
The Link Between Testosterone Deficiency and Metabolic Syndrome
Treatments like orchidectomy (surgical removal of the testicles) and GnRH agonists (like leuprolide) are common ways to lower testosterone in prostate cancer patients. Unfortunately, this testosterone suppression comes with a price. Studies have shown that these treatments can lead to:
- Increased body fat
- Loss of muscle mass
- Higher blood sugar levels
- Elevated cholesterol and triglycerides
Recent Mechanistic Clues
Recent research cited a rat model in which EPA/DHA ethyl esters, sold as Omacor, reversed metabolic changes, lowered systolic blood pressure and left ventricular diastolic stiffness, and reduced inflammatory-cell infiltration and collagen deposition in the heart. Related work identifies testosterone as a regulator of intracellular pathways involved in glucose and lipid metabolism. These findings concern metabolic and cardiovascular effects in experimental models, so they do not by themselves establish that fish oil reduces prostate-cancer treatment side effects in humans.
Mixed Risk Messages
Fish and fish-oil supplements have been promoted for benefits such as cardiovascular treatment, but media reports have also suggested a possible link with increased prostate-cancer risk. Reviews describe these messages as mixed and note that popular commentary has advised against supplemental fish oil, despite other evidence supporting adequate tissue levels of long-chain omega-3 fatty acids. The uncertainty is reflected in the call for clinical trials of Omacor in men with prostate cancer receiving androgen-deprivation therapy rather than treating its benefits as proven.
Supplements Versus Standard Care
The National Cancer Institute reports that complementary and alternative medicine use is common among men with prostate cancer. Its summary says decisions may reflect medical history, beliefs about the safety and side effects of complementary approaches compared with standard treatments, and a desire to feel more in control of treatment. The NCI also describes nutrition methods and supplements as subjects of laboratory and human research for prostate-cancer prevention or treatment, underscoring that investigation does not make them substitutes for established care.
Can Fish Oil Make a Difference?
In the study, rats with induced testosterone deficiency were fed a high-carbohydrate, high-fat diet to mimic the metabolic challenges seen in humans. The researchers then tested whether supplementing their diet with Omacor (a mixture of EPA and DHA ethyl esters) could reverse these negative effects.
A Potentially Less Invasive Path
A UCLA technology report describes a proposed fish-oil-plus-diet regimen intended to minimize the number of patients requiring more invasive options such as surgery or radiation. UCLA researchers reportedly conducted a prospective randomized trial in human patients with prostate cancer and found that the regimen reduced a marker of prostate-cancer aggressiveness after one year. The report presents this as development-stage evidence, so further research is needed before broader clinical conclusions can be drawn.
The results were encouraging. Omacor supplementation showed several benefits:
<ul> <li>Decreased systolic blood pressure</li> <li>Reduced stiffness in the heart</li> <li>Less inflammation and collagen buildup in the heart</li> <li>Reduced fat accumulation in the liver without worsening liver damage</li> </ul><br>These findings suggest that Omacor has the potential to ease metabolic complications in prostate cancer patients undergoing testosterone-lowering therapy.