Loss of weight and muscle mass, common among people with cancer, may be improved with fish oil supplements, according to a new report.

Intestinal upsets make high-dose fish oil capsules difficult for many people with cancer-related wasting to tolerate, but those who are able to take the supplements regularly may be able to stabilize their weight or even gain pounds, according to Dr. C. Patrick Burns of the University of Iowa Carver College of Medicine in Iowa City and colleagues.

Animal studies and some clinical investigations have suggested omega-3 fatty acids found in fish oils may protect against cachexia, as weight loss related to a chronic disease is called. There are three mechanisms by which omega-3s may have this effect, Burns noted in an interview with Reuters Health.

Omega-3s inhibit secretion of inflammatory compounds. Tumors may promote cachexia by releasing factors that stimulate production of these substances, he explained, so the fatty acids would block this process. Also, he added, omega-3 fatty acids may slow protein degradation and fat breakdown.

In the current study, in the medical journal Cancer, 43 patients with moderate to severe malnutrition were prescribed high doses of omega-3 fatty acid supplements. The dose depended the individual’s weight. For example, a person weighing 70 kilograms (about 150 pounds) would take eleven 1-gram capsules per day.

The capsules were divided into two doses, taken with breakfast and lunch. The researchers began the study with twice the dosage, but reduced it because many patients were unwilling or unable to take so many capsules.

Among the 36 participants who took at least some capsules, six were able to gain more than 5 percent of their body weight or achieve their normal weight. Twenty-four other patients stabilized their weight, meaning they gained or lost no more than 5 percent. Six other patients lost more than 5 percent of their body weight.

Side effects were common, and included nausea, vomiting and diarrhea, and the size of the capsules made them difficult for some patients to take.

Nineteen patients stopped treatment early due to side effects, but some other participants tolerated the regimen with few problems, the researchers note.

“It did not seem that gender, age, or ethnicity predicted intolerance, but the study was not powered to test that question,” Burns told Reuters Health.

Future studies of fish oil for cachexia that begin when patients are less severely ill, and last for longer than 30 days, may have more positive results, the researchers conclude.

SOURCE: Cancer, July 15, 2004.