By Alan Gaspari – NutrientJournal.com
Phosphatidylserine (PS) is a naturally occurring phospholipid. It is most abundant in organs with high metabolic activity such as brain, heart, liver, lungs and skeletal muscles . Because of its presence in the brain, phosphatidylserine has been extensively studied in regard to its actions on brain functions. Phosphatidylserine is also marketed as a sports supplement, claimed to aid bodybuilders and power athletes.
Memory and Cognition
Studies suggest phosphatidylserine has an effect on neurotransmitters that may play a role in cognitive functions. It has been shown that treatment with phosphatidylserine enhances cholinergic neurotransmission [2,3] and even increases the turnover of dopamine and norepinephrine in the brain .
In 1986 Delwaide et al.  reported that patients suffering from senile dementia improved their cognitive disorder with oral phosphatidylserine supplementation (derived from bovine brain cortex). Bovine brain cortex derived phosphatidylserine has also been shown to shift EEG power more towards the normal level in patients with mild primary degenerative dementia ; improved behavioral and cognitive parameters were also observed  as well as improved learning and memory in aged rodents [8,10].
However, because of concerns about mad cow disease (bovine spongiform encephalopathy [BSE]) , commercially available products are now made from cabbage or soy. Although the fatty acid composition of soybean lecithin phosphatidylserine is quite different from that of bovine brain , it has been reported to have comparable effects on cognition when compared with bovine brain cortex derived phosphatidylserine . However, beneficial results were reproduced in animal subjects [11-13], while clinical studies remain controversial [14-17].
After 3 months of 300 mg soy-phosphatidylserine, cognitive improvement was reported in elderly humans . Same was reported by Crook et al. . In a double-blind placebo-controlled study by Jorissen et al.  failed to find any beneficial effects of soybean-derived PS (300 or 600 mg/day for 12 weeks) on any aspect of cognitive function including memory, information processing speed, selective attention and planning. A more recent double-blind placebo-controlled study in seventy-eight elderly people with mild cognitive impairment reported significantly improved memory scores relative to placebo .
Phosphatidylserine as Sport Nutrient
During exhaustive intermittent exercise protocol where 14 subjects consumed 750 mg of soybean-derived PS for 10 days, more than 30% reduced time to fatigue was reported without affected serum cortisol levels . While study in downhill runners reported no benefits for muscle soreness, markers of muscle damage, inflammation, and oxidative stress .
Phosphatidylserine has gained some popularity among athletes as it may promote a desirable hormonal balance via blunted release of cortisol following heavy resistance training. This claims are based on a modest evidence reported by few studies showing benefit [1,20,21]. Two small studies reported that 400 and 800 mg of PS taken daily reduces the cortisol rise up to 30% [20-21]. Other studies failed to significantly influence cortisol [18,19,22].
Phosphatidylserin supplementation has no effects on plasma concentrations of lactate, growth hormone  and testosteronelevels [1,22].
Phosphatidylserine Side Effects and Safety
Phosphatidylserine is considered safe when used at recommended dosages. Supplementing with up to 600 mg of phosphatidylserin for 12 weeks has not been associated with any adverse effects .
Phosphatidylserine is sometimes coupled with Ginkgo Biloba because they both appear to enhance cognition. Since ginkgo is known to be a “blood thinner”, PS might be one too as it was reported to enhance the effect of heparin (very strong prescription blood thinner) . So, caution is advised.