Most of the literature on PS and stress focuses on participants performing physical activity as the stressor. However, one researcher conducted three randomized controlled trials in nonathletic populations. These trials don’t provide a clear picture of benefits of PS supplementation for cortisol or perceived stress, although there is some evidence of benefit in participants with a history of high chronic stress. However, study sample characteristics, conflicts of interest, and the fact that the lead author was the same in all three studies reduce our confidence in these findings.
The most recent of these studies, which was conducted in 2014, found no significant effects of phosphatidylserine or phosphatidic acid supplementation on levels of cortisol or adrenocorticotropic hormone (ACTH) following a social stress challenge, although a post-hoc subgroup analysis found some benefit for chronically stressed participants taking the highest level of supplementation; further research would be needed to confirm this result.[1] A similar 2012 study, in which adult male participants supplemented with omega-3 fatty acids in addition to PS, also only found that supplementation had a significant effect in the subgroup of participants with high chronic stress levels; however, in the 2012 study, the size of the cortisol response to acute social stress in the high-chronic-stress subgroup was actually higher after 12 weeks of supplementation (though still lower than that in the low-chronic-stress subgroup). In addition, the high-chronic-stress participants who received PS reported lower perceived stress levels than the participants who received a placebo.[2] Finally, a 2004 study found that when participants who were given either a daily placebo or 400 mg, 600mg, 800 mg of PS daily for 3 weeks were then subjected to a social stress test, only those who had taken 400 mg daily had lower cortisol, ACTH, and distress scores than the placebo group.[3] However, all three of these randomized controlled trials appear to be funded by the companies which provided the supplements for these trials, reducing our confidence in the findings of these studies.