Studies Of Fatty Acid Metabolism With Stable Isotopes During Lactation

Substrates labeled with stable isotopes are ideal to trace dynamic processes in vivo. Their advantage in human studies is the absence of any radiation when compared with the radioactive isotopes. Stable isotopes are naturally occurring and their use has generally been considered as safe and without adverse effects. These advantages are indispensable prerequisites for studies with infants or during pregnancy and lactation. Today stable isotopes are used in a variety of applications for diagnostic and research purposes 11. Different aspects of fatty acid metabolism such as absorption, endogenous synthesis, oxidation and transfer to several body compartments have been investigated. Even in very low birth weight infants this methodologies have recently been applied to demonstrate the in vivo synthesis ofthe LC-PUFA arachidonic and docosahexaenoic acid20.

■ Omnivorous

□ High Carbohydrate a High fish a Vegetarian

Figure 3 : PUFA composition of human milk with different diets (medians or means, wt.% of total fatty acids; drawn from data of Koletzko et al. 13,Sanders and Reddy 19, Finley et al. 4, Muskiet et al. I6and Innis and Kuhnlein9)

■ Omnivorous

□ High Carbohydrate a High fish a Vegetarian

Total Linoleic Arachi- a-Lino- Docosa-PUFA donic lenic hexaenoic

Already more than ten years ago Hachey et al. studied the transfer of dietary triglycerides labeled with stable isotopes in three healthy breastfeeding mothers which remained on their regular diets7. In their study deuterated palmitic, oleic and linoleic acids were given simultaneously with a standardized test meal to the participants. Chylomicrons and VLDL were the lipoproteins primarily involved in the transfer ofthe labeled triglycerides from diet to human milk. They reported a uniform secretion pattern for the three labeled fatty acids to human milk with peak enrichments between 8-10 hours after consumption of the test meal. The long-chain, diet-derived fatty acids accounted for about 29 % of the fat in human milk. In the following we report on some of our recent stable isotope studies that illustrate the metabolism of polyunsaturated fatty acids during lactation.

0 0

Post a comment