DHA turnover in pregnant women using the natural abundance variation of ¹³C: a pilot study

The importance of DHA to support fetal development and maternal health is well established. In this study, we applied the natural abundance approach to determine the contribution of 200 mg/d of DHA supplement to the plasma DHA pool in nineteen healthy pregnant women. Women received DHA, from week 20 until delivery, from an algal source (n 13, Algae group) or from fish oil (n 6, Fish group) with slightly different content of ¹³C. We measured plasma phospholipids DHA ¹³C:¹²C ratio (reported as δ¹³C) prior to supplementation (T0), after 10 (T1) and 90 days (T2) and prior to delivery (T3). The δ¹³C of DHA in algae and fish supplements were -15·8 (sd 0·2) mUr and -25·3 (sd 0·2) mUr (P < 0·001). DHA δ¹³C in the Algae group increased from -27·7 (sd 1·6) mUr (T0) to -21·9 (sd 2·2) mUr (T3) (P < 0·001), whereas there were not significant changes in the Fish group (-27·8 (sd 0·9) mUr at T0 and -27·3 (sd 1·1) mUr at T3, P = 0·09). In the Algae group, 200 mg/d of DHA contributed to the plasma phospholipid pool by a median value of 53 % (31-75 % minimum and maximum). This estimation was not possible in the Fish group. Our results demonstrate the feasibility of assessing the contribution of DHA from an algal source to the plasma DHA pool in pregnant women by the natural abundance approach. Plasma δ¹³C DHA did not change when consuming DHA of fish origin, with almost the same δ¹³C value of that of the pre-supplementation plasma δ¹³C DHA.