The relationship between cod liver oil and prostate cancer is complex and not fully resolved, with studies showing mixed results. Cod liver oil is rich in omega-3 fatty acids (EPA and DHA) and vitamin D, which have been studied for their potential effects on prostate cancer risk and progression. Here’s a concise overview based on available evidence:
- Potential Benefits: Some research suggests omega-3 fatty acids may have anti-inflammatory properties that could reduce prostate cancer risk or slow progression. Preclinical studies and some clinical trials indicate that omega-3s, including those from cod liver oil, may inhibit prostate cancer cell growth, particularly in early-stage disease, by modulating immune responses or reducing tumor-associated inflammation. For example, a 2025 study (CAPFISH-3) found that a high omega-3, low omega-6 diet with fish oil supplements reduced the Ki-67 index (a marker of cancer progression) in men on active surveillance for early-stage prostate cancer. Vitamin D in cod liver oil is also suspected to have a protective effect, though evidence is inconsistent.https://sperlingprostatecenter.com/is-there-something-fishy-about-fish-oil-and-your-prostate/https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5736071/
- Potential Risks: A controversial 2013 study by Brasky et al. linked higher blood levels of omega-3 fatty acids (not specifically cod liver oil) to a 43% increased risk of prostate cancer and a 71% higher risk of high-grade prostate cancer. This study, based on the SELECT trial, sparked concern but was criticized for its observational design, lack of data on fish or supplement intake, and reliance on a single blood sample, which may not reflect long-term omega-3 exposure. Subsequent studies, including a 2021 meta-analysis, found no significant association between omega-3 levels and prostate cancer risk, suggesting the 2013 findings may not hold broadly.https://sperlingprostatecenter.com/omega-3-fatty-acids-beneficial-prostate-cancer/https://prostatecancer.net/clinical/omega-3-fish-oilhttps://www.drweil.com/health-wellness/health-centers/men/does-fish-oil-cause-prostate-cancer/
- Specific to Cod Liver Oil: A 2013 Icelandic study found no statistically significant association between cod liver oil consumption in early or midlife and total or advanced prostate cancer risk. Cod liver oil’s vitamin D content (400 IU per 10 ml) may contribute to any protective effects, but data is limited, and high doses could pose risks due to vitamin A toxicity, though this is unrelated to cancer.https://pmc.ncbi.nlm.nih.gov/articles/PMC3629172/
- Confounding Factors: Study results vary due to differences in methodology, omega-3 sources (diet vs. supplements), fish processing (e.g., smoked or salted fish may increase risk), and population factors like genetics or lifestyle. For instance, Japanese men with high omega-3 intake from fish have lower prostate cancer rates than U.S. men, suggesting dietary context matters.https://pmc.ncbi.nlm.nih.gov/articles/PMC3629172/https://sperlingprostatecenter.com/omega-3-fatty-acids-beneficial-prostate-cancer/https://sperlingprostatecenter.com/is-there-something-fishy-about-fish-oil-and-your-prostate/
- Current Consensus: Evidence is insufficient to definitively link cod liver oil to either increased or decreased prostate cancer risk. Observational studies show conflicting results, and randomized controlled trials are sparse. The American Heart Association still recommends consuming fatty fish twice weekly for heart health, and cod liver oil remains a safe option for most men when taken in moderation. However, concerns about prostate cancer risk are not strong enough to outweigh cardiovascular benefits.https://prostatecancer.net/clinical/omega-3-fish-oilhttps://www.cancer.org.au/iheard/is-it-true-that-men-who-take-fish-oil-supplements-or-eat-fatty-fish-are-more-likely-to-develop-prostate-cancer
Recommendation: If considering cod liver oil, consult your doctor, especially if you have a family history of prostate cancer or are on active surveillance. Discuss dosage (typically 500 mg omega-3 daily) and ensure supplements are high-quality to avoid contaminants. Focus on a balanced diet with whole foods, as nutrients from fish may offer benefits beyond isolated supplements. More research is needed to clarify cod liver oil’s role in prostate cancer prevention or risk.
