Yoga has been a subject of scientific scrutiny for decades now and the main countries performing
research are the United States, Europe, and, of course quite naturally, India.
The problem though is severalfold. First, almost half of published randomized controlled trials (RCTs) on
yoga are conducted in India. Some have argued that the results of such clinical trials tend to be
positively inflated by researchers in Asian countries more so that the United States and Europe. Plus,
and this is a problem plaguing many other research areas, is the problem of publication bias; more
research showing positive results is published than that showing negative or no results.
This problem was examined by a study aimed surveying the RCT research results on yoga by country
published in the complementary, alternative, integrative medicine literature (Cramer et al., 2015). A
selection of RCTs were obtained:
– 131 from India
– 175 from other countries
– 84 from CAIM specialty journals
– 222 from other types of journals
From these, a total of 306 were selected for having met various inclusion criteria. It was found that RCTs
on yoga conducted in India have about 25 times more likely to reach positive conclusions compared to
research from other countries. To the point, about 90 percent of all published RCTs on yoga had positive
conclusions.
Closing Thoughts
Although not the focus of this analysis, it is obvious that RCTs from several other countries, especially Asian countries, also had extremely high frequencies of positive conclusions. There are a number of possible explanations for this finding:
- Yoga might be more effective when practiced in India than elsewhere because it is an integral part of that nation’s spiritual and philosophical tradition. Thus, Indian yoga practice is often more intense than in Europe or North America.
- Indian yoga instructors might be more skilled in teaching yoga than instructors from other non-Indian countries.
- Indian researchers may succumb to the publication bias by being more willing to publish positive results than a negative ones.
But, even then, these possible factors may or may not be enough to push the results being 25 times more positive than non-Asian research. And so, where there is smoke, there is also fire.
It is apparent that Indian research studies into yoga should be carefully evaluated whether or not they are in the clinical context or analyzing past research studies. Further research is needed to corroborate this disturbing finding and to find the reasons for the substantial difference between randomized controlled trials into yoga by Indian researchers versus studies from other countries.
As with everything in this life, caveat emptor.
Paul Shane, Ph.D., LMT
Director, Academic Content
References
Cramer, H., Lauche, R., Langhorst, J., & Dobos, G. (2015). Are Indian yoga trials more likely to be positive than those from other countries? A systematic review of randomized controlled trials. Contemporary Clinical Trials 41, p. 269-272.