November 13, 2013
Omega-3 Fatty Acid Supplements: Too Much of
a Good Thing?

East Lansing, MI—Taking omega-3 fatty acid supplements, such as fish oil, sometimes could be too much of a good thing, especially with so many foods now fortified with the long chain polyunsaturated fatty acids (LCPUFA).

That’s according to a new report, published online by the journal Prostaglandins, Leukotrienes & Essential Fatty Acids. Study authors point out the lack of evidence-based standards for omega-3 intake, despite mounting evidence that high levels can affect immune function.

“What looked like a slam dunk a few years ago may not be as clear cut as we thought,” said co-author Norman Hord, PhD, MPH, RD, associate professor in Oregon State University’s College of Public Health and Human Sciences in Corvallis, OR. “We are seeing the potential for negative effects at really high levels of omega-3 fatty acid consumption. Because we lack valid biomarkers for exposure and knowledge of who might be at risk if consuming excessive amounts, it isn't possible to determine an upper limit at this time.”

A 2010 study led by Michigan State University’s Jenifer Fenton, PhD, MPH, also a co-author on the recent paper, found that feeding mice large amounts of dietary omega-3 fatty acids led to increased risk of inflammatory-like bowel disease and immune alteration. Those results were published in the journal Cancer Research.

In the follow-up, Fenton, Hord, and coauthors reviewed the literature and discuss the potential adverse health outcomes that could result from excess consumption of omega-3 fatty acids.

Omega-3 supplements are popular because of their anti-inflammatory properties and research that has associated them with cardiovascular disease protection and other benefits.

“We were inspired to review the literature based on our findings after recent publications showed increased risk of advanced prostate cancer and atrial fibrillation in those with high blood levels of LCPUFAs,” Fenton said.

Excessive amounts of omega-3 fatty acids can alter immune function, such as affecting “the body's ability to fight microbial pathogens, like bacteria,” Hord noted.

“Our main concern here is the hyper-supplemented individual, who may be taking high-dose omega-3 supplements and eating four to five omega-3-enriched foods per day,” he added. “This could potentially get someone to an excessive amount. As our paper indicates, there may be subgroups of those who may be at risk from consuming excess amounts of these fatty acids.”

“Given the widespread use of supplements and fortification of common food items with LC-omega-3 PUFA, this review focuses on the immunomodulatory effects of the dietary LC-omega-3 PUFAs, EPA and DHA, the mechanistic basis for potential negative health outcomes, and calls for biomarker development and validation as rational first steps towards setting recommended dietary intake levels,” the authors write.

Hord suggested that supplements might be appropriate for those at risk of coronary artery disease after consultation with a health professional; he also said that, generally, the American Heart Association’s dietary recommendations to eat fish, particularly fatty fish at least two times a week, would be sufficient for most people.

U.S. Pharmacist Social Connect