The present invention discloses pharmaceutical/nutritional compositions and methods for alleviating symptoms associated with premenstrual syndrome (PMS) and premenstrual dysphoric disorder (PMDD). The pharmaceutical/nutritional compositions include at least 2% (w/w) phosphatidyl-L-serine, or salts thereof, out of a total effective composition, as a first effective ingredient; and a suitable amount of at least one bio-available form of magnesium as a second effective ingredient. Preferably, the bio-available form of magnesium is magnesium oxide, magnesium citrate, magnesium hydroxide, magnesium stearate, or a magnesium salt of the phosphatidyl-L-serine. Preferably, the composition further includes a pharmaceutical or nutritional excipient. Preferably, the total effective composition is administrable in a multi-part regimen. Preferably, the total effective composition is administrable by intravenous or oral delivery. Preferably, the pharmaceutical/nutritional composition further includes at least 2% (w/w) phosphatidic acid, or salts thereof, out of the total effective composition, as a first effective ingredient.