In March 2014 researchers from Australia published their review of the scientific literature to assess the effect of yoga on high blood pressure levels. A total of 78 studies and 3 case reports were included in the review and involved a total of 6,693 subjects. Results showed that yoga effectively reduced blood pressure levels in all individuals, ie those with normal and with high blood pressure levels. They concluded that although the studies published so far suggest yoga is effective in reducing high blood pressure levels, further high-quality research is required which focusses on the mechanisms of action of different yoga practices.
Tyagi A, Cohen M. Yoga and hypertension: a systematic review. Altern Ther Health Med. 2014 Mar-Apr;20(2):32-59.