It’s been touted for its healthful, anti-inflammatory properties. It’s been recommended for helping ease the pain of arthritis, preventing cancer and slowing memory loss. But some recent studies of fish oil show that it may not always act as advertised—and that you can sometimes have too much of a good thing.

First, the latest news. Researchers spent 18 months following almost 300 patients with mild to moderate Alzheimer’s. Some took fish oil, others a placebo. And there was no difference cognitively between the two groups. The study is in the current Journal of the American Medical Association. [Joseph Quinn et al., "Docosahexaenoic Acid Supplementation and Cognitive Decline in Alzheimer Disease"]

It’s a mixed bag on cancer. A study of more than 35,000 postmenopausal women found that those who took fish oil seemed half as likely to develop breast cancer as those who didn’t. That work was in the July issue of Cancer Epidemiology, Biomarkers & Prevention. [Theodore Brasky et al., "Specialty Supplements and Breast Cancer Risk in the VITamins And Lifestyle (VITAL) Cohort"]

But a study in the October 15th issue of Cancer Research found that mice with inflamed bowels developed colitis and aggressive colon cancer when they were given high doses of fish oil. [Hillary Woodworth et al., "Dietary Fish Oil Alters T Lymphocyte Cell Populations and Exacerbates Disease in a Mouse Model of Inflammatory Colitis"]

So, fish oil might in fact have a healthful role in some circumstances. But you don’t want to swallow every fish story.

—Cynthia Graber

[The above text is an exact transcript of this podcast.]