Fat absorption in premature infants: medium-chain triglycerides and long-chain triglycerides are absorbed from formula at similar rates. Gastrointestinal tolerance, fat absorption, plasma ketone and urinary dicarboxylic acid levels in low-birth-weight infants fed different amounts of medium-chain triglycerides in formula. Comparison of two preterm formulas with or without addition of medium-chain triglycerides (MCTs). I: Effects on nitrogen and fat balance and body composition changes. Decreased glucose oxidation in preterm infants fed a formula containing medium-chain triglycerides. Energy balance in low birth weight infants fed formula of high or low medium-chain triglyceride content. Gastric lipolysis and fat absorption in preterm infants: effect of medium-chain triglyceride or long-chain triglyceride-containing formulas. Nutrient and mineral retention and vitamin D absorption in low-birth-weight infants: effect of medium-chain triglycerides. Use of medium-chain triglycerides in feeding the low-birth-weight infant.
Fat absorption from two different premature infant formulas and one full-term formula containing three different fat blends was investigated in two groups of premature infants. The first group of nine infants (gestational age, 29.1 +/- 0.88 weeks; postnatal age, 3.13 +/- 0.71 weeks) was fed alternately for 1 week each SMA preterm formula containing either high levels (50%) of medium-chain triglycerides (MCT) (6:0, 8:0, and 10:0) or high levels (86%) of long-chain triglycerides (LCT) (greater than or equal to C12). Except for fat blends, the formulas were otherwise identical. The second group of 11 infants (gestational age, 30.5 +/- 0.77 weeks, studied at a postnatal age of 4.33 +/- 0.91 weeks) was fed for 1 week a full-term infant formula, S-26, containing 98% LCT. Fat absorption (studied during a 3-day fat balance period) was similar irrespective of fat blend: 89.08 +/- 2.37% during feeding of preterm SMA, 50% MCT; 87.0 +/- 3.81% during feeding of preterm SMA, 86% LCT; and 83.00 +/- 2.89% during feeding of S-26, 98% LCT. Weight gain (grams per day) and increase in length (centimeters per day) were 23.2 +/- 1.7, 21.20 +/- 1.7, and 14.28 +/- 2.9, and 0.17 +/- 0.06, 0.16 +/- 0.04, and 0.22 +/- 0.07 during feeding of the three fat blends, respectively. Lipase activity levels in fasting gastric aspirates were higher during feeding of the LCT than the MCT formula. The possible stimulation of gastric lipase secretion secondary to long-chain fatty acid stimulation of cholecystokinin secretion might be related to the efficient digestion of formula fat, irrespective of triglyceride-fatty acid chain length.(ABSTRACT TRUNCATED AT 250 WORDS) This study was conducted to evaluate the effect of medium-chain triglycerides (MCT) in a formula for low-birth-weight (LBW) infants on gastrointestinal tolerance, fat absorption, plasma ketone levels, and urinary dicarboxylic acid (DCA) excretion. At the start of enteral feedings, 64 LBW infants (< or = 1500 g) were randomly assigned to one of four experimental formulas. The formulas contained either 0, 17, 34, or 50% of the total fat as MCT oil. The nonfat constituents of all four formulas were the same and identical to Similac Special Care 24 (SCF). Infants were studied from the start of enteral feeding until approximately 7 days after reaching full feeds. Growth and tolerance were assessed in all infants over the entire feeding period. A 48-h balance study was conducted after enteral intake exceeded 100 kcal/kg/day for 3 days. Stool fat, plasma D-(-)-3-hydroxybutyrate (3HB) and carnitine, serum glucose, and urinary DCA levels were determined. Groups did not differ in growth, formula intake, fat absorption (76-84%), serum glucose, or plasma carnitine levels. Gastrointestinal tolerance was excellent and did not differ among groups. Plasma 3HB was significantly different (p < 0.05) only between the 0 and 50% MCT groups, 50 +/- 10 versus 120 +/- 20 microM, respectively. The excretion of urinary DCAs increased with increasing amounts of MCT in the formula. In conclusion, fat absorption and gastrointestinal tolerance were not affected by different MCT levels (0 to 50% of the total fat), but higher levels of plasma 3HB and urinary DCAs were associated with higher levels of MCT in the LBW formulas studied. Medium-chain triglycerides (MCTs) are included in the fat blend of several preterm formulas because of their complete absorption and rapid oxidation. The effects of two different fat blend compositions on nitrogen and fat balances and macronutrient oxidation were investigated in 28 healthy very-low-birth weight infants at 4 weeks of age. A preterm formula with a traditional corn oil/MCT blend containing 38% MCTs (MCT group) was compared to a new fat blend, designed to resemble human milk more, containing 6% MCTs (LCT group). There were no differences in nitrogen absorption or in excretion. Median nitrogen retention was 74% (MCT) vs. 71% (LCT) of intake. Fat absorption was higher (p less than 0.05) in the MCT group (88%) vs. 79% in the LCT group (median values). MCTs did not stimulate fat oxidation as measured by indirect calorimetry, so fat deposition was also higher on the MCT formula. As weight gain was not different between groups, the percentage of weight gain consisting of fat accretion was significantly (p less than 0.005) higher with the MCT formula (24% vs. 21%). On the other hand, there was no increase in percent protein accretion (both 15% of weight gain). We conclude that the existence of a slightly lower fat absorption in the healthy growing neonate fed a LCT formula compared with a MCT formula does not impair growth or nitrogen retention, but merely induces a slight decrease in the high relative fat accretion encountered in the preterm neonate. Several formulas for preterm infants contain medium-chain triglycerides (MCT) to enhance fat absorption. Although fat absorption with MCT was slightly higher in several studies in preterm infants, a beneficial effect on growth has only been reported in one publication. We hypothesized that when part of the fat blend of preterm formula is substituted by MCT oil, this might lead to a different metabolic pattern in which, due to the preferential oxidation of MCT, an increase in lipogenesis from glucose could lead to an increase in metabolic rate. To study the impact of MCT on glucose metabolism, 18 preterm infants were randomized to receive either an MCT or an LCT formula containing 38- and 6%-by-weight medium-chain fatty acids, respectively, in their fat blend. At 4 wk of age, the metabolic rate, substrate utilization, glucose kinetics, and oxidation were measured by indirect respiratory calorimetry in combination with a constant-rate oral infusion of [U-13C]glucose. The "true" rate of appearance of glucose (Ra "true") was measured from the dilution of the uniformly labeled (m + 6) species of infused tracer, whereas "apparent" rate of appearance of glucose (Ra "apparent") was measured from the dilution of infused tracer C (carbon). The latter was measured by an on-line combustion method using a gas chromatograph-isotope ratio mass spectrometer. At a carbohydrate intake of 8.4 mg.kg-1.min-1, total utilization of carbohydrate was equal in both groups at 7.6 mg.kg-1.min-1.(ABSTRACT TRUNCATED AT 250 WORDS) We tested the effect on energy balance of the partial substitution of medium-chain for long-chain triglycerides in the diet of growing low birth weight infants. Fifteen infants were studied in a randomized double-blind crossover clinical trial in which each infant was fed each of two formulas, which were of equal gross energy and protein content but differed in fat composition. The high medium-chain triglyceride (MCT) formula contained medium- and long-chain triglycerides in a weight/weight ratio of 46:54; in the low MCT formula the ratio was 4:96. The hypothesis tested was that under conditions of equal gross energy intake the two diets would differ in their digestible and metabolizable energy contents and would produce differences in the infants' rates of energy expenditure and energy storage. Gross energy intakes averaged 562 and 555 kJ/kg/day (134 and 133 kcal/kg/day) with the high and low MCT formulas, respectively. With each diet, coefficients of energy digestibility (0.93) and metabolizability (0.91) were identical; the rates of energy expenditure were 262 (high MCT) and 265 (low MCT) kJ/kg/day (63 kcal/kg/day for both diets), and of energy storage were 246 (high MCT) and 239 (low MCT) kJ/kg/day (59 and 57 kcal/day). These differences were not significant. There were also no significant differences between the two diets in coefficients of nitrogen retention (mean 0.70) or in rate of weight gain (mean 21.5 gm/kg/day). The use of high MCT content in infant formula neither provided a nutritional advantage in energy digestibility or metabolizability nor resulted in an increased rate of energy expenditure or of energy storage. The extent of gastric lipolysis, fat absorption, and infant weight gain was studied in 12 preterm infants (gestational age 28.75 +/- 0.50 weeks, postnatal age 6.08 +/- 0.81 weeks) fed medium-chain triglyceride or long-chain triglyceride formula for 1 week in a crossover design. The former formula contained 42% of 8:0 and 10:0 and 19% of 12:0, 14:0, and 16:0; the latter formula contained only 7% of 8:0 and 10:0 and 46% of 12:0, 14:0, and 16:0. Gastric aspirates were obtained on the second and third day of formula feeding for quantitation of lipase activity and of the extent of gastric lipolysis. Fat balance studies were conducted during the last three days of each feeding regimen. The study showed that (1) there was marked hydrolysis of formula fat in the stomach during feeding of either medium-chain triglyceride formula or long-chain triglyceride formula (20% and 16%, respectively); (2) lipase activity in the gastric aspirates was less during feeding of medium-chain triglyceride formula than before the meal, which suggested stimulation of lipase secretion by long-chain fatty acid released from long-chain triglyceride formula fat or more rapid binding of lipase to ingested lipid in the medium-chain triglyceride formula; (3) fatty acid distribution in glycerides and free fatty acids showed preferential release of medium-chain (8:0, 10:0) and long-chain unsaturated (18:1, 18:2) fatty acids in the stomach. The low content of 8:0 and 10:0 in gastric triglyceride and free fatty acids suggested that medium-chain fatty acids were absorbed directly in the stomach.(ABSTRACT TRUNCATED AT 250 WORDS) A randomized prospective study of the effect of medium-chain triglycerides (MCT) upon the absorption and retention of major minerals and nutrients, as well as upon 25-hydroxy vitamin D levels, was performed in low-birth-weight infants. Ten infants received a high-calcium and vitamin D-containing formula, which contained 50% of its fat as MCT, while ten other infants received a similar formula in which all the fat was in long-chain triglycerides. There was a five-day delay in reaching full oral feeding volumes, and therefore there was a delay in the onset of the balance study in the MCT group, primarily due to gastrointestinal symptoms. There was a significant improvement in the percent of fat absorption (P less than .05) with MCT, but no difference in the percent of absorption or retention of calcium, phosphorus, sodium, or nitrogen. 25-Hydroxy vitamin D levels decreased in both groups after full oral feeding volumes had been established, but all values were within normal ranges. At the high intake levels of calcium and vitamin D given to the infants, MCT did not increase major mineral or nutrient absorption. Intestinal fat absorption and anthropometric and clinical variables were monitored weekly in 21 low-birth-weight (LBW) infants fed either a whey-predominant cow's-milk formula (formula 1) or identical formulas with medium-chain triglycerides (MCTs) comprising 40% (formula 2) or 80% (formula 3) of the fat content. Fat absorption of infants fed formula 1 averaged 86.7% of intake, whereas that of infants fed formulas 2 and 3 averaged 93.8% and 95.4%, respectively. However, no differences in weight, length, head circumference, or skin fold thickness were observed. Moreover, intestinal symptoms were encountered more frequently in infants fed formulas 2 and 3. This demonstrated failure of the resulting small increase in fat absorption incident to MCTs either to promote enhanced growth or to confer obvious clinical benefit does not support the increasing use of MCT formulas for routine feeding of LBW infants.
There is no evidence of difference between MCT and LCT on short-term growth, gastrointestinal intolerance, or necrotizing enterocolitis. Therefore, neither formula type could be concluded to improve short-term growth or have less adverse effects. Further studies are necessary because the results from the included eight studies are imprecise due to small numbers and do not address important long-term outcomes. Additional research should aim to clarify effects on formula tolerance and on long-term growth and neurodevelopmental outcomes, and include larger study populations to better evaluate effect on NEC incidence.