A recent American Cancer Society statistical report reveals that cancer now exceeds heart disease as the top cause of death among Americans under 85, responsible for 476,009 fatalities compared with 450,637 deaths from heart disease.

What does this have to do with the omega-3s in fish oil? A lot, it seems for people with cancer and for their families.

Omega-3s help curb cancer

A review article published in the December, 2004 issue of the Journal of Nutrition supports the popular medical proposition that omega-3 fatty acids offer an effective, non-toxic adjunct to toxic radiation and chemo therapies.

The available research results indicate that omega-3 fatty acids can constitute a practical alternative therapy for the minority of patients unable to withstand radiation or chemotherapy.

According to the article's authors, dietary omega-3 fatty acids perform three valuable functions:

  • Slow progression of cancers of the lung, colon, breast and prostate (animal studies).
  • Improve the efficacy of toxic cancer drugs such as doxorubicin, epirubicin, CPT-11, 5-fluorouracil, as well as the efficacy of tamoxifen and radiation therapy (animal studies).
  • Improve quality of life in people with cancer, in part by combating cancer-associated appetite loss, physical wasting, and malnutrition.

How do omega-3s fight cancer?

Likely explanations for the benefits of omega-3s include damping of inflammation (a cause and growth promoter of common cancers), increased propensity of cancer cells to “suicide” (apoptosis), and modulation of estrogen signaling (estrogen being linked to breast cancer promotion).

Cancer-prevention power of omega-3s

While the available evidence is stronger for treatment than for prevention, the results of animal, test tube, and human population studies indicate strongly that omega-3s discourage certain cancers from starting: especially leukemia, and cancers of the breast, prostate, and uterine endometrial tissue.

There is limited evidence that omega-3s prevent cancer in general, but this gap in the evidence is attributable to three factors:

  • Human trials are very expensive
  • Drug companies lack any financial incentive to study nutritional prevention strategies,
  • Animal and test tube studies are much easier and cheaper to implement, control and measure.

As many researchers have said, it seems logical that a nutrient that slows cancer growth via proven physiological effects should also help reduce cancer risk.

Eat your omega-3s!

The takeaway lesson seems clear: omega-3s may prevent cancer, and definitely do three things: slow cancer growth, enhance conventional treatment, reduce damaging muscle-wasting, and present a credible alternative when conventional treatment is not an option.


  • Astorg P. Dietary N-6 and N-3 polyunsaturated fatty acids and prostate cancer risk: a review of epidemiological and experimental evidence. Cancer Causes Control. 2004 May;15(4):367-86. Review.
  • Augustsson K, Michaud DS, Rimm EB, Leitzmann MF, Stampfer MJ, Willett WC, Giovannucci E. A prospective study of intake of fish and marine fatty acids and prostate cancer. Cancer Epidemiol Biomarkers Prev. 2003 Jan;12(1):64-7.
  • Folsom AR, Demissie Z. Fish intake, marine omega-3 fatty acids, and mortality in a cohort of postmenopausal women. Am J Epidemiol. 2004 Nov 15;160(10):1005-10.
  • Gago-Dominguez M, Yuan JM, Sun CL, Lee HP, Yu MC. Opposing effects of dietary n-3 and n-6 fatty acids on mammary carcinogenesis: The Singapore Chinese Health Study. Br J Cancer. 2003 Nov 3;89(9):1686-92.
  • Goodstine SL, Zheng T, Holford TR, Ward BA, Carter D, Owens PH, Mayne ST. Dietary (n-3)/(n-6) fatty acid ratio: possible relationship to premenopausal but not postmenopausal breast cancer risk in U.S. women. J Nutr. 2003 May;133(5):1409-14.
  • Hardman WE. (n-3) fatty acids and cancer therapy. J Nutr. 2004 Dec;134(12 Suppl):3427S-3430S. Review.
  • Jho DH, Babcock TA, Tevar R, Helton WS, Espat NJ. Eicosapentaenoic acid supplementation reduces tumor volume and attenuates cachexia in a rat model of progressive non-metastasizing malignancy. JPEN J Parenter Enteral Nutr. 2002 Sep-Oct;26(5):291-7.
  • Larsson SC, Kumlin M, Ingelman-Sundberg M, Wolk A. Dietary long-chain n-3 fatty acids for the prevention of cancer: a review of potential mechanisms. Am J Clin Nutr. 2004 Jun;79(6):935-45. Review.
  • Roynette CE, Calder PC, Dupertuis YM, Pichard C. n-3 polyunsaturated fatty acids and colon cancer prevention. Clin Nutr. 2004 Apr;23(2):139-51. Review.
  • Stoll BA. N-3 fatty acids and lipid peroxidation in breast cancer inhibition. Br J Nutr. 2002 Mar;87(3):193-8. Review.
  • Terry P, Lichtenstein P, Feychting M, Ahlbom A, Wolk A. Fatty fish consumption and risk of prostate cancer. Lancet. 2001 Jun 2;357(9270):1764-6.
  • Terry P, Wolk A, Vainio H, Weiderpass E. Fatty fish consumption lowers the risk of endometrial cancer: a nationwide case-control study in Sweden. Cancer Epidemiol Biomarkers Prev. 2002 Jan;11(1):143-5.
  • Terry PD, Terry JB, Rohan TE. Long-chain (n-3) fatty acid intake and risk of cancers of the breast and the prostate: recent epidemiological studies, biological mechanisms, and directions for future research. J Nutr. 2004 Dec;134(12 Suppl):3412S-3420S. Review.