Healthnotes Newswire (April 20, 2006)—A special type of fatty acid derived from soybeans may improve exercise endurance, according to Medicine and Science in Sports and Exercise (2006;38:64–71). Men who took phosphatidylserine for ten days were able to engage in heavy exercise longer than men who took a placebo. The research suggests a new direction for the supplement, which is better known to support cognitive function and memory.

Fourteen healthy men participated in the double-blind trial, which consisted of two exercise tests. In each test, the men completed three ten-minute stages of cycling at rates calculated to bring them to 45, 55, and then 65% of their maximal oxygen uptake, followed by a final exercise bout at 85% that was continued until exhaustion. All exercise stages were interspaced with five-minute rest periods. After a five-day recovery period, the men began supplementing with either phosphatidylserine (750 mg per day) or placebo for ten days. On the eleventh day, they had the second exercise test, which was identical in design to the first.

The men who took the phosphatidylserine supplement had significantly increased exercise capacity compared with the men who took a placebo. On average, it took the phosphatidylserine group two minutes longer to reach exhaustion than it did prior to supplementation. Those taking placebo experienced no change in exercise capacity.

Phosphatidylserine is a naturally occurring phospholipid. Phospholipids are important parts of cell membranes, made up of a water-loving phosphate component and a water-hating lipid component. These properties help determine the structure of biological membranes and allow for the movement of material in and out of cells. Phosphatidylserine is naturally concentrated in organs with high metabolic activity. Its main functions are to help maintain a proper balance of minerals in tissues and to stimulate certain enzymes involved in energy metabolism.

Phosphatidylserine was formerly derived from bovine brain, but due to concerns about possible transmission of infectious disease, it is now derived from soybeans, as was the material used in the present study. Although the differently sourced phosphatidylserines appear to have the same biological effects, no side-by-side clinical comparison has been done.

The mechanism by which phosphatidylserine improved endurance is not known. However, given its known functions within the body, it suggests that the supplement delayed the onset of fatigue by maintaining stable levels of calcium, sodium, and potassium in heart and skeletal muscle tissues for longer during exercise.