Fish-oil supplements high in omega-3 fatty acids may improve the body's ability to build muscle and help stave off age-related immobility, according to a study conducted by researchers from the University of Aberdeen, U.K., and presented at the British Science Festival in the same city.
Hope for stroke patients.
Fatty fish and fish-oil supplements have gained popularity in recent years due to their high content of omega-3s, which research has linked to improve cardiovascular health, improved cognitive function and a lower risk of death. Fish oil itself has been linked to a lower risk of cancer and to improved healing after a stroke.
Studies conducted on farm animals have shown that a diet rich in omega-3s leads to an increase in muscle mass. These studies inspired the Aberdeen researchers to perform a similar study on laboratory rats. Using magnetic resonance imaging, the researchers found that middle-aged rats whose diet included fish oil lost significantly less lean mass over time than similarly aged rats fed only a standard diet.
"The fish oil seemed to be having anabolic [muscle-building] protective effects in the rats, but rats aren't humans, so the next step was to try it in humans," lead researcher Stuart Gray said.
Battling muscle loss
A certain degree of muscle loss, known as sarcopenia, is typically considered a normal part of healthy aging. Healthy sarcopenia results in a 0.5 to two percent reduction in muscle size per year. Excessive sarcopenia; however, can lead to weakness, frailty and immobility in the elderly.
In the United States, one in four people between the ages of 50 and 70 demonstrate signs of sarcopenia, along with more than 50 percent of those over the age of 80. In addition to the direct effects of immobility, sarcopenia can cause other injuries due to falls.
"Around 1.5 percent of the total U.S. healthcare budget is spent on sarcopenia-related issues," Gray said.
The rate of sarcopenia can be strongly affected by differences in lifestyle and diet, with low protein intake and a low activity level exacerbating the condition. In the current study, the researchers sought to find out if a diet high in omega-3s would have a similar effect in humans as it did in farm animals and laboratory rats.
The researchers assigned 14 women over the age of 65 to participate in two 30-minute leg exercise sessions per week for 12 weeks. Half of the women were given an olive oil (placebo) supplement, while the other half were given a supplement containing the omega-3 fatty acids DHA and EPA. At the end of the study, the women taking olive oil supplements had experienced an 11 percent increase in muscle mass, while the women taking omega-3s had experienced a 20 percent increase, nearly twice as much as the placebo.
The researchers have already secured funding for a follow-up study, to be performed on 60 men and women over the age of 65. With the new study, researchers aim to confirm the findings of their first study and also to see if they can determine exactly how omega-3s influence muscle formation and retention.
The new study will also seek to determine whether men and women respond differently to omega-3s. Previous studies have shown that men's and women's bodies are different; both in their response to exercise and in their protein synthesis abilities.
"Older women have similar levels of protein synthesis to younger women, whereas older men have lower levels compared to younger men," Gray said. "Older men adapt to exercise and increase their protein synthesis. Older women don't do this to a great extent, although their basal levels of synthesis are higher."
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