Millions of Americans ­– 20.4 million as of 2012, in fact – practice yoga. It has become a panacea of sorts, with suggested benefits ranging from decreased stress and improved overall health to better looks and hotter sex.

While much research has confirmed the benefits of yoga, a new yoga study out from the University of Ohio can boast that it is the largest, randomized controlled trial that includes biological measures. The study looked at the effect of yoga on women who had undergone breast cancer treatment; the conclusions are significant.

Each of the 200 participants had finished all breast cancer treatments before the study started and only those new to yoga were included. The women practiced group yoga twice a week for 12 weeks. They were encouraged to practice at home on their own as well.

As soon as the initial 12-week phase of the trial was complete, the women in the yoga group reported an average 41 percent decrease in fatigue and a 12 percent higher vitality score compared to a non-yoga control group, according to a press statement for the study.

Six months after the the study was started, tests showed that on average, fatigue was 57 percent lower in women who had practiced yoga compared to the non-yoga group. Inflammation was reduced by up to 20 percent, which was determined by measuring the activation of protein inflammation markers in the blood.

"This showed that modest yoga practice over a period of several months could have substantial benefits for breast cancer survivors," said Janice Kiecolt-Glaser, lead author of the study and professor of psychiatry and psychology at The Ohio State University.

The researchers zeroed in on breast cancer patients because the treatment can be so debilitating, noting that the fatigue brought about by treatment leads to a reduction of fitness and an ensuing downward spiral. This is one of the reasons, Kiecolt-Glaser says, that cancer survivors have high levels of inflammation.

A secondary analysis revealed that more yoga produced even better results. Increased yoga practice yielded more positive changes in fatigue, vitality and depressive symptoms and a four to six percent reduction in two of the three pro-inflammatory proteins. Significant improvement in sleep was reported as well.

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

The study was published in the Journal of Clinical Oncology.

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