UNITED STATES, February 7, 2014 (National Geographic): The more we learn about yoga, the more we realize the benefits aren't all in the minds of the 20 million or so devotees in the U.S. Yoga helps people to relax, making the heart rate go down, which is great for those with high blood pressure. The poses help increase flexibility and strength, bringing relief to back pain sufferers.
Now, in the largest study of yoga that used biological measures to assess results, it seems that those meditative sun salutations and downward dog poses can reduce inflammation, the body's way of reacting to injury or irritation. That's important because inflammation is associated with chronic diseases including heart disease, diabetes, and arthritis. It's also one of the reasons that cancer survivors commonly feel fatigue for months, even years, following treatment.
Researchers looked at 200 breast cancer survivors who had not practiced yoga before. Half the group continued to ignore yoga, while the other half received twice-weekly, 90-minute classes for 12 weeks, with take-home DVDs. According to the study, which was led by Janice Kiecolt-Glaser, professor of psychiatry and psychology at Ohio State University, and published in the Journal of Clinical Oncology, the group that had practiced yoga reported less fatigue and higher levels of vitality three months after treatment had ended.
But the study didn't rely only on self-reports. Kiecolt-Glaser's husband and research partner, Ronald Glaser of the university's department of molecular virology, immunology, and medical genetics, went for stronger, laboratory proof. He examined three cytokines, proteins in the blood that are markers for inflammation. Blood tests before and after the trial showed that, after three months of yoga practice, all three markers for inflammation were lower by 10 to 15 percent. That part of the study offered some rare biological evidence of the benefits of yoga in a large trial that went beyond people's own reports of how they feel.