Changes in the fatty acid profiles of red blood cell membrane phospholipids in human neonates during the first month of life.

We have studied the changes in the fatty acid profiles of red blood cell membrane phospholipids in 47 infants who were exclusively fed human milk from birth to 1 month of life. Twenty blood samples were obtained from cord, 15 at 7 days and 12 at 30 days after birth. Membrane phospholipids were obtained from erythrocyte ghosts by thin-layer chromatography and fatty acid composition was determined by gas liquid chromatography. Phosphatidylcholine showed the most important changes during early life; stearic, w6 eicosatrienoic and arachidonic acids decreased whereas oleic and linoleic acids increased. In phosphatidylethanolamine, palmitic and stearic acid declined and oleic, linoleic and docosahexenoic acids increased with advancing age. Small changes were noted for individual fatty acids in phosphatidylserine. In sphingomyelin stearic acid increased from birth to 1 month and linoleic, arachidonic and nervonic acids decreased. Total polyunsaturated fatty acids of the w6 series greater than 18 carbon atoms increased with advancing age in phosphatidylethanolamine and decreased in choline and serine phosphoglycerides and in sphingomyelin. Long chain fatty acids derived from linoleic acid decreased in phosphatidylcholine but increased in ethanolamine and serine phosphoglycerides. The different behavior in the changes observed in fatty acid patterns for each erythrocyte membrane phospholipid may be a consequence of its different location in the cell membrane bilayer and specific exchange with plasma lipid fractions.

Lipid composition of liver microsomes in rats fed a high monounsaturated fatty acid diet.

The fatty acid and cholesterol contents of tissue membranes are the determinants of membrane stability and functionality. This study was designed to evaluate the influence of a high monounsaturated fatty acid diet on the fatty acid composition of rat liver microsomes and on their cholesterol and lipid phosphorus content. Weanling animals were fed for 5 weeks with high fat diets containing olive oil or corn oil. Saturated fatty acids were increased and oleic acid decreased in microsomal total phospholipids and in the three major phosphoglycerides, phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylinositol (PI), of rats fed corn oil as compared to the olive oil group. The percentage of linoleic acid was higher in the corn oil group, but only for total phospholipids and PC. Linoleic and alpha-linolenic metabolites were significantly increased in total phospholipids of olive oil-fed animals with respect to those fed corn oil. These changes were responsible for the low unsaturation index found in microsomal phospholipids of the corn oil group. The diet did not affect the microsome cholesterol or the lipid phosphorus content. These results show that, in olive oil-fed rats, the cholesterol content and the degree of unsaturation of liver microsomes was similar to that observed in weanling animals; this probably suggests an adequate maintenance of functionality of membranes in olive oil-fed animals.

Changes in the fatty acids pattern of red blood cell phospholipids induced by type of milk, dietary nucleotide supplementation, and postnatal age in preterm infants.

The fatty acid profile of red blood cell phospholipids and the total phospholipid and cholesterol contents of erythrocyte membrane in preterm infants in the first month of life were studied. Influences of human milk and adapted formula and dietary nucleotides supplementation at a level similar to that found in human milk were evaluated. Nineteen preterm newborn infants with adequate weight for gestational age were fed their own mother's preterm human milk, 18 with a standard milk formula and 18 with the same formula supplemented with nucleotides. Blood samples were obtained at birth from cord blood, and at 30 days of age. At 1 month of life, linoleic acid rose in formula fed infants compared to those fed human milk (p less than 0.05) and relative amounts of 20:3w6, 20:4w6, 22:4w6, 22:5w6, and total polyunsaturates of the w6 series greater than 18 carbon atoms were significantly decreased in standard milk formula fed infants (p less than 0.05-0.01). No significant differences for these fatty acids were found between human milk and nucleotide milk formula infants. Docosahexaenoic acid (22:6w3) decreased from birth to 1 month of age in formula fed infants (p less than 0.01) but not in human milk fed infants. Infants fed nucleotide milk formula showed intermediate values for 20:3w6 and 20:4w6 (p less than 0.1) between infants fed human milk and those fed standard milk formula.(ABSTRACT TRUNCATED AT 250 WORDS)

Changes in the fatty acid profiles of plasma lipid fractions induced by dietary nucleotides in infants born at term.

This study was designed to determine the polyunsaturated fatty acid (PUFA) composition of plasma lipid fractions in newborn infants fed human milk (HM), milk formula (MF) or nucleotide-supplemented milk formula (NMF) during the first month of life. Linoleic acid was increased in infants fed formulas in all plasma lipid fractions with respect to those fed HM. Plasma phospholipids in MF-fed infants had lower percentages of PUFA of both omega 6 and omega 3 series, namely arachidonic and docosahexaenoic acids, than those fed HM or NMF; the unsaturation index was decreased in infants fed MF as compared to those fed HM or NMF. Arachidonic acid showed a similar behaviour in plasma cholesteryl esters as in phospholipids. No changes for long chain PUFA among the groups studied were observed for plasma triglycerides and free fatty acids. These results support previous findings that dietary nucleotides are involved in the regulation of desaturation and elongation of linoleic and linolenic acid to their longer superior homologous fatty acids. We suggest that dietary nucleotides may reverse the partial inhibition of delta 5-desaturase caused by an excess of linoleic acid in the diet during early postnatal life.

Influences of diet and postnatal age on the lipid composition of red blood cell membrane in newborn infants.

The fatty acid and cholesterol contents of tissue membranes are determinants of their stability and functionality. This study was designed to evaluate the influences of diet and postnatal age on the polyunsaturated fatty acid (PUFA) composition of erythrocyte membrane phospholipid fractions and on the red blood cell membrane cholesterol and phosphorus contents in newborn infants during the 1st month of life. A group of infants was fed on human milk and another group on adapted milk formula. Blood samples were obtained at birth, from cord blood, and at 7 and 30 days of age. Long-chain w6 PUFA declined with advancing age in all membrane phosphoglycerides and sphingomyelin (SM) in those infants fed formula. w6 PUFA also decreased in phosphatidylcholine (PC) and phosphatidylserine (PS) in infants fed human milk and were maintained constant in phosphatidylethanolamine (PE) and SM. w3 PUFA were less affected by postnatal age. PE and SM showed significantly higher percentages of w6 and w3 long-chain PUFA in infants fed human milk than in those fed formula. Membrane cholesterol content increased in all infants from birth to 1 month of life but phosphorus levels were unaffected by diet and postnatal age. These results suggest that diets with a low content of long-chain PUFA, such as adapted cow's milk formulas, may induce changes in membrane functionality and that incorporation of PUFA to the diet in amounts similar to those found in human milk should be considered at least in early life.

Changes in the fatty acid composition of plasma and red blood cell membrane during the first hours of life in human neonates.

The objective of this work was to examine the changes in the fatty acid profiles of plasma lipid fractions and red blood cell membrane phospholipids in newborn infants during the first 6-8 h of life. Methyl esters of fatty acids from plasma free fatty acids and phospholipids and from membrane phosphatidylethanolamine, phosphatidylcholine and sphingomyelin for cord blood (n = 20) and venous blood (n = 19) were analyzed by GLC. Important changes were observed in plasma fatty acids. Palmitic and palmitoleic acid increased from birth to 6-8 h of age for both free fatty acids and phospholipids. Palmitic acid also increased in membrane phosphatidylcholine and phosphatidylethanolamine. In the former, stearic acid declined whereas oleic and docosatetraenoic acids increased. Phosphatidylethanolamine and sphingomyelin were less affected than phosphatidylcholine probably because the internal location of the two first fractions in erythrocyte membrane. Polyunsaturated fatty acids dropped slightly during the first hours of life in most lipid fractions. This may be a consequence of the interruption of placental fatty acid supply and the limited capacity of the newborn to desaturate their essential fatty acid tissue stores.