Practicing yoga may do more than calm the mind — it may help protect against certain diseases, a new study suggests.
In the study, women who had practiced yoga regularly for at least two years were found to have lower levels of inflammation in their bodies than did women who only recently took up the activity. Inflammation is an immune response and can be beneficial when your body is fighting off infection, but chronically high levels of inflammation are known to play a role in certain conditions, including asthma, cardiovascular disease and depression.
Inflammation is known to be boosted by stressful situations. But when yoga experts were exposed to stress (such as dipping their feet in ice water,) they experienced less of an increase in their inflammatory response than yoga novices did.
"The study is the first one, I think, to really suggest how yoga could have some distinctive physical benefits in terms of the immune system," said researcher Janice Kiecolt-Glaser of Ohio State University. "It suggests that regular yoga practice is really good for you." she told LiveScience.
Kiecolt-Glaser and her Ohio State colleagues recruited 50 women between the ages of 30 and 65 and with different degrees of yoga experience. Those labeled "yoga experts" had practiced yoga once or twice a week for at least two years, while "yoga novices" had participated in only six to 12 sessions. (The researchers wanted novices to have at least some experience so that they wouldn't be stressed out simply from having to practice yoga for the first time.)
The two groups were very similar in terms of age, physical fitness level and amount of body fat. This was important because all three of these factors are known to influence inflammation. Participants completed three stressful tasks in succession. In one, subjects immersed a foot in warm water and then in ice water for one minute. In another, they had to perform tricky mental arithmetic for five minutes.
Then subjects either completed a yoga session or took part in one of two control experiments, which involved walking on a treadmill, or watching a video.
All the while, subjects had catheters placed in their arms to collect blood samples periodically. The researchers examined the blood samples for key markers of inflammation, one of which is a protein called IL-6.
Across all the tasks and other experimental scenarios, the novices' IL-6 levels were 41 percent higher than the experts'. The novices also produced more IL-6 in response to the stressful tasks.
While the researchers aren't sure why yoga would have this effect on inflammation, they have a few speculations.
Yoga focuses on deep breathing and controlling breathing, which may slow down the body's "fight or flight" response — the body's reaction to stress, Kiecolt-Glaser said.
Yoga also involves meditation, which helps people learn to pay attention to how they are feeling. So yoga experts may be more aware of their stress and better able to control their response to it.
Finally, yoga is a form of exercise, which is known to decrease inflammation.
A randomized clinical trial will be needed to confirm the findings, Kiecolt-Glaser said. Such a trial would involve randomly assigning participants to either practice yoga or refrain from it over a certain time frame. Researchers would then look to see whether the activity had any effect on inflammation.
The study was published in the January issue of the journal Psychosomatic Medicine. Kiecolt-Glaser also discussed her study at the 118th annual Convention of the American Psychological Association, which was held Aug. 11 to Aug. 14 in San Diego.