Are you one of those who take omega-3 fatty acid supplements like fish oil daily to reap the health benefits? Beware, these may be rancid pills and not as healthy as they claim, a new study suggests.
Omega-3 supplements derived from plants (algae) and seafood (fish, krill, etc.), sometimes labeled as fish oil, are commonly used because of research that shows they may have health benefits.
Rancidity is measured by the amount of oxidation of the oil in the additive.
When food supplements oxidize, the nutritional value to consumers decreases. "Our research shows that many of these supplements are not fresh -- and thus may not be beneficial for health," said Leigh A. Frame, associate professor and director of clinical research at George Washington University in the United States.
Higher levels of omega-3 fatty acids have been linked to many benefits for multiple organs, including the brain and eyes, but the most common reason for its popularity among consumers is its support for the cardiovascular system.
Researchers conducted six-year tests on 72 of the most popular brands of omega-3 supplements using recommended rancidity limits voluntarily set by GOED, an international trade group representing omega-3 manufacturers.
According to the results published in the Journal of Dietary Supplements, a total of 45 percent of the flavored and unflavored supplements were rancid, 32 percent of the flavored supplements were positive, and 13 percent of the unflavored pills. However, the added flavor can mask the rancidity of the supplements.
Although oxidation occurs in the flavorings, indicating a positive rancidity index, Frame said the amount of oxidation is unknown because of the flavoring compounds themselves.
"Fragrance can mask the freshness of omega-3 supplements in two ways," said lead author Jacob Hands, a medical student in the university's School of Medicine and Health Sciences.
When fresh, fish oil supplements do not have the taste or smell of fish, he explained.
"Fragrance can mask these aspects, but it also makes it difficult for researchers to determine the level of oxidation and the quality of the additive."
Although there are third parties that test vitamins and supplements to ensure the purity of the ingredients on the label, even tested brands cannot guarantee freshness, Frame explained. Both the framework and the arms suggest that flavored fish oil additives should be used with caution at this stage, as it is uncertain how flavor may affect their freshness and thus health benefits.