Cancer can leave patients feeling run down, worn out and overall fatigued by their disease and the treatments that fight it. The malaise often lingers even after cancer treatment is over. But a new study from the Mayo Clinic found that ginseng may be a tool for fighting cancer-related fatigue.

Researchers gave 2,000 milligrams of pure ground American ginseng or a placebo pill to 340 patients being treated for cancer and cancer survivors who had finished their treatment. After four weeks, patients reported little change in their cancer-related fatigue. But after eight weeks, the patients taking ginseng reported feeling generally more energized than their sugar pill-popping peers. The response was particularly strong among patients who were currently undergoing cancer treatment.

The study was presented today at a meeting of the American Society of Clinical Oncology.

Dr. Debra Barton, an associate professor of oncology at the Mayo Clinic and the study's lead author, said knowing how to combat fatigue, one of the most common side effects reported during and after cancer treatment, is becoming increasingly important.

"We are making progress in cancer treatment, and we do have more survivors than ever before, so we can't just ignore these quality-of-life factors once the cancer is gone," she said.

Doctors often caution patients against taking supplements that might interfere with their cancer treatment drugs. According to the National Center for Complementary and Alternative Medicine, potential adverse interactions with prescription medications are one of the primary safety concerns with taking herbs and other supplements. In recent years, patients undergoing cancer treatment have reported adverse reactions after taking ginseng.

Barton said it's important for patients to tell their doctors about all the supplements they're taking. But she said recent research on ginseng is encouraging.

"Ginseng is one of the more studied herbs," she said.

Some studies have shown that ginseng decreases inflammation and the stress hormone cortisol, both of which may be contributing factors to cancer-related fatigue. Barton and her team plan to study how ginseng affected these biological factors in the patients in the current trial.

But because herbs and dietary supplements are largely unregulated by the federal government, Barton said it's important for fatigued patients to be smart consumers. When purchasing ginseng supplements, consumers should look for the amount and type of the herb the product contains, as well as how the plant is prepared.

"Extracts of ginseng that are alcohol based change a characteristic of the ginseng to be somewhat estrogenic, which of course is something women with breast cancer should be aware of," she said. "Stay with very reputable companies, and try to get information on how the herb is processed."