In mammals, the ability to use nutrients from food and convert them into muscle proteins decreases with age. Though the exact cause of this phenomenon is still unclear, insulin resistance of aging muscle cells has been suggested as a possible answer.

Since omega-3 fatty acids are known to improve glucose metabolism in people and animals showing insulin resistance, the researchers decided to test whether omega-3’s could also influence protein metabolism.

To do so, they added supplements containing either omega-3’s from fish oil or a mixture of cottonseed and olive oils without omega-3’s to the regular diet of steers. After five weeks, animals with the marine omega-3 diet showed increased sensitivity to insulin which, in turn, improved protein metabolism: twice the amount of Amino Acids was used by their bodies to synthesize proteins, especially in muscles. So it appears that omega-3 fatty acids added to the steers’ diet replaced other fatty acids in muscle cells and improved their functioning.

This finding could have significant implications in the field of animal farming, according to Thivierge, also a professor in Université Laval’s Department of Animal Sciences, who undertook this study in order to find an alternative to hormonal growth stimulation in beef cattle.

At 4 to 6 months of age, calves become less efficient at converting food into muscle mass, which has a negative impact on farming profitability. "Adding fish oil to their diet could prevent this decline by restoring insulin sensitivity in aging animals," suggests the researcher. "In addition, it could contribute to reducing the amount of by-product emissions in the environment, since animals that are given omega-3’s spontaneously eat 10% less food to achieve the same weight gain," points out Thivierge.

Restoring insulin sensitivity through the use of marine omega-3 fatty acids could also prevent the loss of muscle mass in older people and, by the same token, prevent the various health problems associated with it, believes Thivierge. She also suggests that omega-3’s could help athletes trying to increase their muscle mass. "However, it should not be seen as a miracle product," she points out. "For increased muscle protein metabolism to take place in people younger than 50, physical training is still required," she concludes.