Phosphatidylserine

Template:Chembox new Phosphatidylserine (PS or PtdSer) is a phospholipid nutrient found in fish, green leafy vegetables, soybeans, and rice, and is essential for the normal functioning of neuronal cell membranes, activating protein kinase C (PKC), which has been shown to be involved in memory function. Phosphatidylserine is usually kept on the inner-leaflet of cell membranes by an enzyme called translocase. In apoptosis, caspase 3 activation culminates in deactivation of translocase and activation of scramblase, which allows free movement of PtdSer down its concentration gradient, and activation of flippase, which transports PtdSer to the outer-leaflet of the plasma membrane. This is part of the process by which the cell is targeted for phagocytosis.

Health Benefits

Memory and Cognition

PS has been shown to slow cognitive decline in animal models.

PS has been investigated in a small number of double-blind placebo trials and has been shown to increase memory performance in the elderly. Because of the potential cognitive benefits of phosphatidylserine, the substance is sold as a dietary supplement to people that believe they can benefit from an increased intake.

The dietary supplement was originally processed from bovine sources, however prion disease scares in the 1990s outlawed this process, and a soy-based alternative was adopted. The fatty acids attached to the serine in the soy product are not identical to those in the bovine product, which is also impure. Studies using the soy version indicate a possible improvement in mood, but no clear evidence of an effect on mental function.

On May 13, 2003, the U.S. Food and Drug Administration gave "qualified health claim" status to phospahtidylserine, stating that "Consumption of phosphatidylserine may reduce the risk of dementia in the elderly" and "Consumption of phosphatidylserine may reduce the risk of cognitive dysfunction in the elderly"

Sports Nutrition

Phosphatidylserine has been demonstrated to speed up recovery, prevent muscle soreness, improve well-being, and might possess ergogenic properties in athletes involved in cycling, weight training and endurance running. PS has been reported to be an effective supplement for combating exercise-induced stress and preventing the physiological deterioration that accompanies too much exercise. In recent studies, PS has been shown to enhance mood in a cohort of young people during mental stress and to improve accuracy during tee-off by increasing the stress resistance of golfer's.

Attention-deficit hyperactivity disorder

First pilot studies indicate that PS supplementation might be beneficial for children with attention-deficit hyperactivity disorder.

Dietary Sources

PS can be found in meat fish, but is most abundant in the brain and in innards such as liver and kidney. Only small amounts of PS can be found in dairy products or in vegetables, with the exception of white beans.

Table 1. PS content in different foods.

Food	PS Content in mg/100 g
Bovine Brain	713
Mackerel	480
Herring	360
Eel	335
Innards (average value)	305
Tuna	194
Poultry (average value)	110
Beans	107
Beef	69
Pork	57
Whole Grain	20
Rice (unpolished)	3
Milk (3.5% fat)	1

Changes in our daily diet (rejection of innards, low-fat, low-cholesterol and reduced meat diets) have resulted in a significant decrease of dietary PS consumption during recent years. The average daily PS intake from the diet in western countries is estimated to be 130 mg.<ref name="Jäger_2007">

Applications

Research

Annexin-A5 is a naturally-occurring protein with avid binding affinity for PS. Labeled-annexin-A5 enables visualization of cells in the early- to mid-apoptotic state in vitro or in vivo.

Medical

Tumour

Technetium-labeled annexin-A5 enables distinction between malignant and benign tumours whose pathology includes a high rate of cell division and apoptosis in malignant compared with a low rate of apoptosis in benign tumours.

External links

• DrugBank info page
• Phosphatidylserine and Cognitive Dysfunction and Dementia
• Phosphatidylserines at the U.S. National Library of Medicine Medical Subject Headings (MeSH)