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[Essential fatty acids and prematurity: a triple experimental approach]
1Laboratoire de Biologie et Biochimie des Lipides, Université de Montpellier I.
Comptes Rendus Des Seances De La Societe De Biologie Et De Ses Filiales
|January 1, 1995
Summary
Preterm newborns can convert alpha-linolenic acid (AAL) into DHA, supporting its supplementation in formulas. This conversion is confirmed by in vitro and in vivo studies, indicating a viable pathway for DHA synthesis.
Area of Science:
- Biochemistry
- Neonatal Nutrition
- Maternal-Fetal Medicine
Background:
- Fetal plasma shows higher arachidonic acid (AA) and docosahexaenoic acid (DHA) than maternal plasma.
- Precursor C18 fatty acids (linoleic acid - AL, alpha-linolenic acid - AAL) are lower in fetal plasma, raising questions about PUFA origin and fetal conversion abilities.
- Placental desaturation is not a factor, necessitating investigation into fetal liver capacity for converting C18 precursors to long-chain PUFAs.
Purpose of the Study:
- To investigate the origin of long-chain polyunsaturated fatty acids (PUFAs) in fetal plasma.
- To determine the fetal liver's ability to desaturate and elongate C18 fatty acid precursors.
- To provide a rationale for infant formula supplementation with either LC-PUFAs or their C18 precursors.
Main Methods:
- Multicentric nutritional study supplementing premature newborns (n=88) with AAL under specific AL/AAL ratios and intake levels.
- In vitro investigation of delta 6 and delta 5 desaturase activities in fetal livers using radiolabeled substrates.
- In vivo studies using stable isotopes (13C or deuterium) in term infants to trace C18 fatty acid conversion.
Main Results:
- Formula supplementation with AAL in preterm infants resulted in DHA status closer to human milk feeding compared to standard formulas.
- Significant delta 6 and delta 5 desaturase activities were detected in fetal livers, confirming conversion capabilities.
- Limited desaturase activity, particularly in the n-6 pathway, was observed, with substrate inhibition noted for delta 5 desaturation.
- Stable isotope studies confirmed the conversion of C18 essential fatty acids into AA and DHA in term infants.
Conclusions:
- Preterm newborns possess the capacity to convert alpha-linolenic acid (AAL) into DHA, especially when precursor fatty acid supplies are balanced.
- The findings support the supplementation of infant formulas with AAL to improve DHA status in preterm neonates.
- Understanding fetal and neonatal fatty acid metabolism is crucial for optimizing nutritional strategies and infant development.