Phospholipids

Phospholipids were, until recently, known to be responsible for off-flavor development in vegetable oils and other lipid-containing foods during storage. The oxidation sensitivity of phospholipids has been attributed to the higher degree of unsaturation of their fatty acid constituents. Phospholipids constitute the structural lipids of plant cell membranes and account for up to 10% of total lipids in oilseeds, depending on the type of seed examined (Belitz and Grosch, 1987). However, more recent studies have demonstrated that phospholipids may act as antioxidants, as they exert a synergistic effect when present together with tocols and ascorbates. Nonetheless, the exact mechanism and mode of action of phospholipids remains speculative. With respect to the claims related to the potential memory improvements upon consumption of phosphatidylserine, although the presence of docosahexaenoic acid (DHA) in brain phospholipids was originally thought to be responsible for the effects, more recent studies have provided evidence that the cognition-enhancing effects originally ascribed to bovine cortex were duplicated by phosphatidylserine from egg and soybean sources (Blokland et al., 1999). In addition, choline and phosphatidylcholine (lecithin) have been shown to have beneficial effects in enhancing cognition (Ladd et al., 1993; Meck and Williams, 1999).

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