Synthesis of long-chain polyunsaturated fatty acids in preterm newborns fed formula with long-chain polyunsaturated fatty acids
2007
Carnielli, Virgilio P. | Simonato, Manuela | Verlato, Giovanna | Luijendijk, Ingrid | De Curtis, Mario | Sauer, Pieter JJ | Cogo, Paola E.
BACKGROUND: Docosahexaenoic acid (DHA) and arachidonic acid (AA) are long-chain polyunsaturated fatty acids (LCPs) that play pivotal roles in growth and neurodevelopment. OBJECTIVE: We aimed to quantify the synthesis of LCPs in preterm infants fed infant formula containing LCPs. DESIGN: Twenty-two preterm infants were randomly assigned to either the no-LCP group (fed formula without LCPs; n = 11) or the LCP group (fed formula with LCPs; n = 11). Dietary LCPs had higher ¹³C content than did the endogenously synthesized LCPs, which were derived from linoleic and α-linolenic acids. The ¹³C content of major selected plasma fatty acids was measured by using gas chromatography-isotope ratio mass spectrometry at birth and at age 1, 3, and 7 mo. Absolute LCP synthesis and the percentage of LCP synthesis relative to dietary intake were calculated. RESULTS: Percentage AA synthesis was 67.2 ± 7.8%, 35.9 ± 9.8%, and 29.0 ± 10.3%, and that of DHA was 41.7 ± 14.9%, 10.5 ± 8.1%, and 7.4 ± 6.2% at 1, 3, and 7 mo old, respectively. Absolute AA synthesis was 26.7 ± 4.2, 14.4 ± 3.9, and 11.6 ± 4.1 mg · kg⁻¹ · d⁻¹ and that of DHA was 12.6 ± 4.5, 3.2 ± 2.5, and 2.3 ± 1.9 mg · kg⁻¹ · d⁻¹ at 1, 3, and 7 mo old, respectively. AA and DHA synthesis decreased significantly (P < 0.01) with time, and AA synthesis was significantly (P < 0.01) greater than DHA synthesis. CONCLUSIONS: By this novel approach, we measured endogenous LCP synthesis in infants receiving dietary LCPs over long periods. By age 7 mo, LCP synthesis was dramatically lower in preterm infants fed LCPs.
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