Effects of oral L-carnitine supplementation on in vivo long-chain fatty acid oxidation in healthy adults.

Despite an abundance of literature describing the basic mechanisms of action of L-carnitine metabolism, there remains some uncertainty regarding the effects of oral L-carnitine supplementation on in vivo fatty acid oxidation in normal subjects under normal conditions. It is well known that L-carnitine normalizes the metabolism of long-chain fatty acids in cases of carnitine deficiency. However, it has not yet been shown that L-carnitine influences the metabolism of long-chain fatty acids in subjects without disturbances in fatty acid metabolism. Therefore, we investigated the effects of oral L-carnitine supplementation on in vivo long-chain fatty acid oxidation by measuring 1-[(13)C] palmitic acid oxidation in healthy subjects before and after L-carnitine supplementation (3 x 1 g/d for 10 days). We observed a significant increase in (13)CO(2) exhalation. This is the first investigation to conclusively demonstrate that oral L-carnitine supplementation results in an increase in long-chain fatty acid oxidation in vivo in subjects without L-carnitine deficiency or without prolonged fatty acid metabolism.

[Post-conceptional age. Effect on protein requirements of premature infants]. / Das postkonzeptionelle Alter. Einfluss auf den Proteinbedarf Frühgeborener.

In 12 preterm infants (mean gestational age: 28.9 weeks; mean birthweight: 1230 g) (Group 1) the serum concentrations of urea and alpha-amino-nitrogen were studied during the 32nd and between the 36th and 37th week of post-conceptional age. In 9 preterm infants with a mean gestational age of 34.6 weeks (mean birthweight: 1860 g) (Group 2) the same parameters were estimated during the 36th or 37th week of postconceptional age. In all male infants (group 1: n = 6; group 2: n = 5) the excretion of nitrogen in urine and stools were measured during a 48 h balance period. During the study all infants were fed with human milk enriched with 3 g of a bovine human milk fortifier (Eoprotin, Milupa AG, Germany) per 100 ml human milk (mean protein intake: 3.4 g/kg.day; mean caloric intake: 132.5 kcal/kg.day). Despite the similar protein and energy intakes on all study days the serum concentrations of urea and alpha-amino-nitrogen were significantly higher during the 36th or 37th postconceptional week if compared to those found during the 32nd postconceptional week. This was accompanied by elevated renal excretion of total nitrogen due to an increased excretion of urea in the older infants. The nitrogen excretions in stools were low during both study periods. During the period 36 and 37 weeks of postconceptional age no differences could be found for all parameters studied between the both groups of different gestational ages. The data of the present study suggest that in preterm infants with postconceptional age of 37 weeks or more protein intakes of 3.4 g/kg.day and more may exceed the requirements of these infants. Thus, supplementation of human milk with protein is not necessary after the 37th week of postconceptional age if feeding volumes of 170 ml/kg.day or more are tolerated.

The application of redissolved human milk lyophilisate for nutrition of very low birth weight infants.

In the second month of life the nitrogen and fat balances were studied in 21 very low birth weight infants fed with native human milk or redissolved human milk lyophilizate. Caused by fat losses during the lyophilization procedure and decreased fat absorption rate as consequence of heating of the milk before lyophilization, the available energy is significantly lower in infants fed with redissolved human milk lyophilizate than in those fed with native human milk. The reduced energy intake leads to a decreased protein utilization, as well as to a poor weight gain. In addition, hyperaminoacidaemia and hyperaminoaciduria appear in these infants. Thus, supplementation with medium-chain triglycerides must be recommended if redissolved human milk lyophilizate is used for feeding very low birth weight infants.

[Protein metabolism in the small for gestational age newborn in relation to the severity of fetal malnutrition]. / Proteinstoffwechsel hypotropher Neugeborener in Abhängigkeit vom Schweregrad der Hypotrophie.

The daily nitrogen balance, the amino acid concentrations in serum and urine, and the bile acid concentrations in the serum on the eighth day of life were estimated in newborn infants small for gestational age with different degrees of fetal malnutrition. The amino acid concentrations in urine and serum as well as the total nitrogen losses by urine increase in dependence on the severity of fetal malnutrition. In addition the bile acid concentrations were elevated whereas the urea concentrations in serum remained unchanged. These results point to a deranged liver function which depends on the degree of fetal malnutrition. These special metabolic conditions have to be considered in the nutrition of such infants. The bile acid concentrations seem to be an efficient parameter to estimate this metabolic situation.