Yoga’s role in medicine has always been somewhat controversial. Some evidence has suggested it can be quite effective for certain conditions, while other research has been less encouraging.

But now, a new study has found that yoga can be helpful for women who have survived breast cancer.

What's interesting is that not only does yoga seem to affect women’s subjective sense of well-being, as yoga practice is known to do, it also affects health at the molecular level: It reduces inflammation, and you can detect the change in the blood.

Three months later, the women who’d practiced yoga reported 40% less fatigue, and increased vitality, as well as reduced levels of three key inflammatory proteins.

The new study set out to determine whether yoga might affect several measures of well-being, like energy, fatigue, depression and sleep quality. The researchers also wanted to see whether yoga might be linked to three key markers of inflammation, since chronic inflammation is tied to a number of potentially life-threatening health problems, including cancer, coronary heart disease, Type 2 diabetes, osteoporosis, and Alzheimer’s disease.

Two hundred women, all in remission from breast cancer and between two and three years away from their last radiation treatment or surgery, rated their levels of fatigue, energy, depressive symptoms, sleep quality. They also noted their physical activities and food consumption.

Some of the cancer survivors took two 90-minute yoga classes each week and were encouraged to practice (and log their time doing so) at home as well. The other women were placed on a wait-list, and served as a control group.

Three months later, the women who’d practiced yoga reported 40% less fatigue, and increased vitality (a measure of energy level), compared to the control group, though there weren’t differences in most of the other measures at the end of the treatment period.

It wasn't just the women's subjective ratings that differed — the blood work of those taking yoga showed it, too. Women who took yoga had reduced levels of three key inflammatory proteins: interleukin-6 (IL-6), interleukin-1 beta (IL-1B) and tumor necrosis factor-alpha (TNF-a). The proteins were almost 20% lower in the yoga group, compared to women who didn’t do yoga.

Women who practiced yoga more often than the required 90-sessions also had additional reductions in inflammation, along with improved sleep quality, and fewer symptoms of depression.

The authors say the differences in fatigue and depression are comparable to those seen with aerobic exercise and strength training, which has been assessed in previous studies.

“We were really surprised by the data because some more recent studies on exercise have suggested that exercise interventions may not necessarily lower inflammation unless people are substantially overweight or have metabolic problems,” study author Janice Kiecolt-Glaser said in a statement.

The effects held up over time. After six months, the women reported a more than 50% reduction in fatigue, and their inflammatory markers were still down. The team suspects that improved sleep quality may be responsible for at least some of the benefits.

“…[I]mproved sleep could be part of the mechanism of what we were seeing. When women were sleeping better, inflammation could have been lowered by that, ” Kiecolt-Glaser said. When women feel less tired they are better able to take on other activities over time that further improve health, she noted.

The effects seen here are likely to be relevant to people who have never had cancer, the team believe. But that will have to be addressed in a future study.

“Yoga has many parts to it — meditation, breathing, stretching and strengthening,” said Kiecolt-Glaser. “We think the breathing and meditation components were really important in terms of some of the changes we were seeing.”

If you’re curious about yoga or meditation, it may be worth giving one or both a try. The research suggests that they may significantly improve your well being — in ways that you can see and feel, and in those you can’t.

The study was carried out by a team at Ohio State University and published in the Journal of Clinical Oncology.