Abstract
Approximately 15–30% of the body’s need for choline is met by de novo synthesis using phosphatidylethanolamine methyltransferase (PEMT) which sequentially methylates phosphatidylethanolamine (PE) to form phosphatidylcholine (PtdCho). PE preferentially has long unsaturated fatty acids such as docosahexaenoic acid (DHA, C22:6) in the sn-2 position. In previous studies, we have shown that PEMT knockout mice significantly decreased PtdCho-DHA and choline pools in their livers and plasma. We were interested in whether this PtdCho-DHA could be a surrogate marker for liver PEMT activity, and therefore, provide information on choline status in humans. To that end, adult men and women were fed a diet containing 550 mg choline/day for 10 days. They were then fed a choline deficient diet for up to 42 days, before being repleted with graded amounts of choline. Blood was collected at the end of each phase, and plasma separated and analyzed for PtdCho-derived DHA using gas chromatography. To date, subjects who were deemed clinically choline deficient (developed hepatic steatosis) on the low choline diet had approximately 20% lower plasma PtdCho-DHA at the end of the depletion (p= 0.016) and the repletion phases (p= 0.003), when compared to the baseline phase (3.3 + 0.2 % of total fatty acids). Subjects who had no functional changes when fed a choline deficient diet for 42 days, had no differences in their plasma PtdCho-DHA. Thus, PtdCho-DHA may be a useful indicator of choline deficiency. This research is supported by grants from NIH- DK55865, DK56350 and RR00046.
Published Version
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