Phosphatidylserine (PS) is a phospholipid component of cell membranes, particularly in the brain, and is sometimes used as a dietary supplement to support cognitive function and mental health. There is some scientific evidence suggesting that phosphatidylserine may have a beneficial effect on mood, particularly in populations experiencing stress or cognitive decline. A few small clinical studies have indicated that PS supplementation can help reduce stress-induced cortisol release and improve mood parameters in older adults and individuals subjected to mental stress. For example, a randomized, double-blind study published in the journal Stress (2004) found that PS supplementation reduced stress and improved mood in young adults subjected to mental stressors. Another study in elderly women with depression-like symptoms (Acta Psychiatrica Scandinavica, 1990) reported that PS, sometimes in combination with omega-3 fatty acids, produced improvements in mood.

However, the overall body of evidence remains limited. Most studies have small sample sizes, short durations, or methodological limitations. There are few, if any, large-scale, high-quality trials specifically examining PS for "mood swings" in otherwise healthy individuals or in those with mood disorders. As such, while there is some preliminary scientific support for phosphatidylserine's effect on mood, the evidence is not strong or conclusive, and its use should be considered experimental for mood swings until more robust data are available.