NEW YORK (Reuters Health) - Breast cancer survivors who eat a healthy dose of omega-3 fats may have some extra energy throughout their day, a new study suggests.
Many people treated for cancer have lingering fatigue, even years after their therapy ends. There's evidence that good sleep habits and regular exercise can help, if people can keep those things up.
But there's still a need for other options, experts say.
Exactly what causes cancer survivors' long-term fatigue is unclear, according to Dr. Rachel Ballard-Barbash of the U.S. National Cancer Institute, who worked on the new study.
But there's evidence that chronic inflammation in the body may play a role, she said in an interview.
Omega-3 fats -- found largely in oily fish like salmon, mackerel and tuna -- are thought to lessen inflammation.
That's especially true, research suggests, if the omega-3 replace some of the omega-6 fatty acids that make a large share of the typical American diet. Omega-6 fats are found in margarine, vegetable oils and an array of snack foods, sweets and fast food; too much omega-6 is thought to promote inflammation.
So for their study, Ballard-Barbash and her colleagues looked at the relationship between omega-3 intake and fatigue among 633 breast cancer survivors.
Overall, 42 percent of the women were considered "fatigued" three years after their diagnosis. And the problem was more common in those with higher blood levels of an inflammation-related protein called CRP.
On the other hand, women who got more omega-3 in their diets had lower odds of fatigue, particularly if they used fish oil pills.
Of women who got the most omega-3 relative to omega-6, at least partly from fish oil supplements, about 23 percent were considered fatigued.
That compared with 49 percent of women who did not use supplements and had the lowest omega-3 intake relative to omega-6.
Of course, other factors may separate fish and fish-oil lovers from other people.
But when the researchers accounted for factors like women's age, race and weight, higher omega-3 intake was still linked to lower odds of fatigue.
However, Ballard-Barbash said it's too early for people with cancer-related fatigue to invest in fish oil pills -- which can run anywhere from a few dollars to more than $15 for a month's supply of one-gram supplements.
"I wouldn't recommend that women start taking supplements," she said.
On the other hand, adding some fish to your diet might be wise.
"Consuming fish a couple times a week -- particularly fatty fish -- is already recommended to the general public, for overall health," Ballard-Barbash noted. So that's something that breast cancer survivors with fatigue can do for themselves, she said.
She also recommended that women who are not physically active already look into taking up an exercise routine.
As for fish oil? "A next step," Ballard-Barbash said, "could be for randomized clinical trials to test whether increasing amounts of omega-3, either dietary or supplements, could lead to a decrease in inflammation, and a decrease in fatigue."
In randomized clinical trials, researchers randomly assign some people to take the "real" treatment and others to take an inactive placebo. Those types of studies are considered the "gold standard" for proving a therapy really works.
SOURCE: Journal of Clinical Oncology, online March 12, 2012.