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Phosphatidylserine Lowers Cortisol, Increases Testosterone

By CP Staff

Researchers have found that phosphatidylserine blunts the increased cortisol response that occurs after intense exercise and that it can increase testosterone levels.

Previous research has indicated that phosphatidylserine supplementation reduces the high cortisol levels that occur after heavy exercise and that this effect may be dose related. To build upon these past studies, researchers conducted a new study to determine the effect of phosphatidylserine on blood concentrations of cortisol, lactate, growth hormone and testosterone, before, during and after moderate intensity exercise.

In the double-blind, placebo, crossover trial, ten healthy male subjects consumed either 600 mg per day of phosphatidylserine or a placebo for ten days. After 10 days, the five subjects who consumed phosphatidylserine switched to the placebo group for ten days while the subjects who were taking the placebo began taking phosphatidylserine. Blood samples were taken at rest, after 15 minutes of moderate intensity exercise, and during a 65-minute passive recovery.

Cortisol concentrations decreased by 39 percent following phosphatidylserine administration compared to the placebo. Free testosterone levels also increased when subjects were taking the phosphatidylserine compared to the placebo. This improvement in testosterone resulted in an 184 percent improvement in the testosterone to cortisol ratio. Neither the placebo nor phosphatidylserine affected growth hormone or lactate levels.

The researchers concluded, “The findings suggest that PS is an effective supplement for combating exercise-induced stress and preventing the physiological deterioration that can accompany too much exercise.”


Starks MA, Starks SL, Kingsley M, Purpura M, Jager R. The Effects of Phosphatidylserine on Endocrine Response to Moderate Intensity Exercise. Journal of the International Society of Sports Nutrition. 2008;5:11.