Phosphatidylcholine: A Key Source of DHA
Phosphatidylcholine (PC) refers to a family of molecules containing glycerol, phosphocholine, and 2 fatty acids. The fatty acids in PC can substantially differ, leading to an array of different PCs with the potential for different roles in the body. Recently, PCs have been identified as a critical carrier of the omega 3 fatty acid, docosahexaenoic acid (DHA) in the blood.
Mice lacking the gene, PEMT, a prominent methyl-transferring enzyme required for one pathway of PC synthesis in the liver, exhibit substantially reduced levels of DHA in the blood (Watkins, Zhu and Zeisel, 2003; Forman, 2005; Lazar, 2017). Furthermore, mice born to mothers lacking PEMT exhibit reduced DHA accumulation in the brain (da Costa et al., 2010), linking PC synthesis in the mother’s liver to the supply of a key nutrient for fetal neuronal development.
Importantly, a lack of adequate methyl donor nutrients, such as choline, or genetic variants that impact the activity of PEMT, can then influence the amount of DHA circulating in the blood to be taken up by tissues (da Costa et al., 2011) - an effect that is likely pronounced during pregnancy, during which PEMT activity typically increases dramatically in response to estrogen. Few studies of DHA supplementation, especially the large literature base in pregnancy, have adequately considered the influence of choline intake, or the impact of common genetic variants in PEMT, on their results.