FATTY ACID COMPOSITION OF PLASMA AND RED CELL PHOSPHOGLYCERIDES IN FULL TERM INFANTS AND THEIR MOTHERS1

Methods have been adapted and their reproducibility tested for the determination of blood lipids and the fatty acid composition of the phosphoglycerides. The main lipid classes in 20 women from the south-western part of Sweden at term pregnancy and of umbilical cord plasma of their newborn infants were studied. Determinations were made of the fatty acid pattern of plasma phosphoglycerides and of cephalins and lecithin of red cells. The concentration of the major lipid classes in maternal and umbilical cord plasma agreed well with previously reported figures from other countries. The maternal plasma fatty acid pattern of phosphoglycerides was similar to that of adult males. The mothers and their infants had identical concentrations of the total sum of all polyunsaturated fatty acids in plasma phosphoglycerides, in red cell lecithin and in red cell cephalins. The infants' pattern differed from the mothers' by much lower concentrations of the parent fatty acids, linoleic and linolenic acids, and correspondingly increased concentrations of the more polyunsaturated fatty acids of the two series. The fatty acid composition in the red cell lecithin of mother and infant reflected that in the corresponding plasma. The cephalins contained more polyunsaturated fatty acids than the lecithin in both mothers' and infants' red cells. The study produced no biochemical evidence of an essential fatty acid deficiency in these newborns. The identical concentration of total polyunsaturated fatty acids in blood phosphoglycerides of mothers and infants in combination with the pronounced change in the ratio between the parent fatty acids and the highly polyunsaturated derivates, suggest a homeo-static regulation of the fatty acid composition of the blood phosphoglycerides.     

Faecal short chain fatty acids in breast-fed and formula-fed babies

Edwards CA, Parrett AM, Balmer SE, Wharton BA. Faecal short chain fatty acids in breast-fed and formula-fed babies. Acta Pædiatr 1994;83:459–62. Stockholm. ISSN 0803–5253
The intestinal flora of breast-fed infants differs from that of formula-fed infants. It is thought that this difference in flora may be one important reason why breast-fed babies suffer less from gastrointestinal disease. Differences in intestinal flora are reflected in the profile of faecal short chain fatty acids (SCFA). Very little is known about faecal concentrations of SCFA in babies fed breast milk or infant formula. In this study, faecal SCFA were measured in babies at two and four weeks of age who had been either exclusively breast fed or bottle fed from birth. There was no significant difference in total faecal SCFA concentrations between breast-fed and formula-fed babies when lactate was included. The formula-fed group, however, had less lactic acid and higher concentrations of propionic and n-buytric acids than breast-fed babies. Very few babies had significant levels of n-butyric acid, although this SCFA is believed to be important for the health of the colonic mucosa of adults.     

Acute C-Peptide, Insulin and Branched Chain Amino Acid Response to Feeding in Formula and Breast Fed Infants

ABSTRACT. The response of C-peptide in serum and urine and of glucose and branched chain amino acids in blood to formula and breast feeding was assessed in six breast-fed and six formula-fed infants 3–6 months of age. We analysed serum C-peptide, branched chain amino acids (BCAA) in blood, and blood glucose in the fasting state at 90' and 180' after regular meal. The excretion of urinary C-peptide and creatinine was also determined. The formula-fed infants received formula in current use, containing 15–16 g protein/l and with casein/whey ratio of 40/60. In the fasting state, no significant inter-group difference was found in the level of serum C-peptide or the valine/glycine ratio. Postprandially, the formula-fed infants had significantly higher serum C-peptide values and valine/glycine ratio than the breast-fed infants, p ≤0.05. No significant inter-group difference was found for blood glucose. The urinary C-pep-tide/creatinine ratio was significantly lower in the breast-fed group, p =0.02, and significantly correlated both to the valine/glycine ratio at 90', r_s =0.75, p =0.02 and to the serum C-peptide value at 90', r_s =0.66, p =0.03. These results confirm that in formula-fed infants the insulin response to meal is enhanced compared to that in breast-fed infants. The finding of similar blood glucose values in the two groups may also indicate an insulin resistance in the formula-fed infants following meal.     

Effects of dietary long-chain polyunsaturated fatty acids on the essential fatty acid status of premature infants

The effect of different diets on the percentage content of long-chain polyunsaturated fatty acids (LCP; metabolites of linoleic and alpha-linolenic acids) in plasma lipids was studied in 29 premature infants on days 4 and 21 of life. Eleven infants were fed human milk which supplies LCP (1.7% of the fatty acids), 10 a commercially available milk formula without LCP, and 8 a new formula enriched with LCP of the omega-6 and the omega-3 series (0.5% LCP). LCP values in plasma lipids remained stable during the observation period in infants fed human milk. In contrast, LCP decreased markedly in plasma lipids of infants fed the conventional formula. Since the precursor fatty acids linoleic and alpha-linolenic acids were high in their diet and plasma, this finding indicates that premature infants have a limited capacity for LCP biosynthesis and may require their dietary supplementation. Infants fed the LCP enriched formula had significantly higher LCP proportions in plasma lipids than infants given the conventional formula, but less than infants fed human milk. Our results demonstrate that small concentrations of dietary LCP have marked effects on plasma lipid composition, particularly on phospholipids, suggesting that dietary LCP are preferentially channelled into structural lipids. We conclude that the essential fatty acid status of formula-fed premature infants can be improved by a supplementation of omega-6- and omega-3-LCP.Abbreviation LCP long-chain polyunsaturated fatty acids     

Tryptophan fortification of adapted formula increases plasma tryptophan concentrations to levels not different from those found in breast-fed infants.

Several recent studies have demonstrated significantly lower plasma total tryptophan concentrations in formula-fed than in breast-fed infants. We have measured preprandial plasma amino acid concentrations in infants breast-fed or fed a formula with a protein concentration of 1.57 g/dl and with a whey/casein ratio of 60:40 or a formula with a protein concentration of 1.37 g/dl and a whey/casein ratio of 40:60 and fortified with 10 mg/dl (15 mg/100 kcal) of tryptophan. Healthy term infants (10 per group) were either breast-fed from birth or randomly assigned to one of the two study formulas. At 4 and 12 weeks of age, anthropometric measurements were performed and blood samples were obtained. During the study period of 12 weeks, all infants showed normal growth (weight, length, and head circumference) and there were no statistically significant differences between the groups. The plasma concentrations of the essential amino acids phenylalanine, threonine, valine, and lysine were significantly lower in the breast-fed group than in both formula-fed groups. For tyrosine, methionine, leucine, histidine, isoleucine, and arginine, no significant differences could be found between the feeding groups. Concentration of total plasma tryptophan was significantly higher in the breast-fed group than in the group fed the tryptophan-unfortified formula, but no statistically significant difference could be found between the plasma tryptophan concentration in the breast-fed group versus the group fed the tryptophan-fortified formula. The results indicate that tryptophan fortification of adapted formula is necessary to achieve plasma total tryptophan concentrations similar to those found in breast-fed infants.(ABSTRACT TRUNCATED AT 250 WORDS)     

Red blood cell fatty acid composition in low-birth-weight infants fed either human milk or formula during the first months of life

The fatty acid composition of red blood cell (RBC) phospholipids in low-birth-weight infants was determined immediately after delivery and during the first 3 months of life. In the first study, infants were fed either human milk or two formulas with different fatty acid compositions but no long chain polyunsaturated fatty acids (LCPUFA). Both groups of formula-fed infants had significantly lower levels of docosahexaenoic acid (DHA) in RBC phospholipids compared with breast-fed infants. RBC phospholipid DHA was similar in the two formula groups at all ages. In the second study, infants received either a non-supplemented or a LCPUFA-supplemented formula. DHA remained stable in RBC phospholipids of infants supplemented with LCPUFA, whereas DHA decreased in RBC phospholipids of unsupplemented infants. These results confirm that adding DHA to formulas is more effective than increasing 18:3 n-3 content, in maintaining RBC phospholipid DHA levels.     

Protein and energy intake during weaning. III. Effects on plasma amino acids

Preprandial plasma amino acid concentrations were measured at 5 and 6 months of age in 30 healthy term infants who were either breast-fed ad libitum or fed one of two different formulas (1.9 g of protein per 100 ml with a whey:casein ratio of 50:50; 2.9 g of protein per 100 ml with a whey:casein ratio of 20:80) ad libitum, plus the same supplementary food regimen. The mean plasma concentrations of total amino acids and especially total essential amino acids were higher in the formula-fed infants. Those fed formula also had plasma concentrations of methionine, isoleucine, phenylalanine, leucine, valine, threonine, aspartate, proline, lysine, tyrosine, histidine that exceeded plasma concentrations of breast-fed infants by 2 or more standard deviations. Concentrations of arginine, glutamic acid, glutamine, ornithine, serine, cystine did not differ and taurine was higher in the breast-fed infants. The data indicate that formulas in common use today during weaning (4-6 months) provide excessive protein intakes when compared to the breast-fed control infants. A lowering of protein concentration and a further manipulation of the whey:casein ratio is necessary if plasma amino acid patterns similar to those found in breast-fed infants is to be achieved with artificial feeding.     

Protein and Energy Intake during Weaning

ABSTRACT. Preprandial plasma amino acid concentrations were measured at 5 and 6 months of age in 30 healthy term infants who were either breast-fed ad libitum or fed one of two different formulas (1.9 g of protein per 100 ml with a whey: casein ratio of 50:50; 2.9 g of protein per 100 ml with a whey: casein ratio of 20:80) ad libitum, plus the same supplementary food regimen. The mean plasma concentrations of total amino acids and especially total essential amino acids were higher in the formula-fed infants. Those fed formula also had plasma concentrations of methionine, isoleucine, phenylalanine, leucine, valine, threonine, aspartate, proline, lysine, tyrosine, histidine that exceeded plasma concentrations of breast-fed infants by 2 or more standard deviations. Concentrations of arginine, glutamic acid, glutamine, ornithine, serine, cystine did not differ and taurine was higher in the breast-fed infants. The data indicate that formulas in common use today during weaning (4–6 months) provide excessive protein intakes when compared to the breast-fed control infants. A lowering of protein concentration and a further manipulation of the whey: casein ratio is necessary if plasma amino acid patterns similar to those found in breast-fed infants is to be achieved with artificial feeding.     

Age and diet effects on fecal bile acids in infants

Fecal bile acid patterns and concentrations have been determined for 28 infants who were followed from average ages of 3-11 months. Half were solely breast-fed and half were solely formula-fed at the beginning of the study. Breast-fed infants were found to have significantly (p less than 0.05) lower concentrations of cholic acid than the formula-fed group, up to an average age of 5 months. Concentrations of deoxycholic and lithocholic acids were directionally lower in breast-fed infants at all ages. Concentrations of chenodeoxycholic acid were similar for both groups throughout the study. At the end of the study, breast-fed infants were excreting 17% of their total bile acids in the form of secondary acids, compared to 33% for formula-fed infants. This pattern persisted long after the infants began weaning. Formula-fed infants were found to have lithocholic acid in their stools at a significantly (p less than 0.05) earlier age than breast-fed infants. Appearance of deoxycholic acid was at similar ages for both groups. Both of these secondary acids were found to occur at much younger ages (approximately 2 months) than has been previously reported. These observed differences are attributed to the distinct intestinal microbial populations encouraged by the different diets.     

Impact of early dietary intake and blood lipid composition of long-chain polyunsaturated fatty acids on later visual development

BACKGROUND: In contrast to human milk, current infant formulas in the United States do not contain omega3 and omega6 long-chain polyunsaturated fatty acids. This may lead to suboptimal blood lipid fatty acid profiles and to a measurable diminution of visual function in developing term infants. The need for docosahexaenoic acid and arachidonic acid supplementation in the infant diet was evaluated in a double-blind, randomized clinical trial. METHODS: Healthy term infants were randomized to diets of (1) commercial formula, (2) docosahexaenoic acid-enriched formula (0.35% of total fatty acids), or (3) docosahexaenoic acid- (0.36%) and arachidonic acid- (0.72%) enriched formula. Eighty-seven infants completed the 17-week nutritional trial, and 58 were observed until 52 weeks of life. A reference group was exclusively breast fed for at least 17 weeks (n = 29). Outcome measures included electroretinographic responses, visual evoked potentials, and blood fatty acid analysis in infants at birth and at 6, 17, and 52 weeks of age. RESULTS: Commercial formula-fed infants had 30% to 50% lower content of docosahexaenoic acid in total red blood cell lipids during the 17-week feeding trial compared with breastfed infants. Significant differences persisted at the 1-year follow-up. Arachidonic acid content was consistently reduced in the commercial formula group by 15% to 20%. Infants fed long-chain polyunsaturated fatty acid-enriched formulas had docosahexaenoic acid and arachidonic acid blood lipid profiles resembling those of human milk-fed infants. Infants receiving this enriched formula had more mature electroretinographic responses than commercial formula-fed infants at 6 weeks of age. Human milk-fed and docosahexaenoic acid-enriched formula-fed infants had better visual acuity than commercial formula-fed infants at both 17 and 52 weeks of age. Early (17-week) fatty acid profiles in blood lipids were correlated with later (52-week) visual function development in study infants. CONCLUSIONS: Results from this clinical trial demonstrate that long-chain polyunsaturated fatty acid supplementation of formula in term infants produces blood lipid fatty acid profiles that are similar to those observed in breast-fed infants. This supplementation leads to better visual function later in life (i.e., 1 year of age) than that shown by infants fed commercial formula.     

Changes in erythrocyte lipid stroma in the premature infant according to dietary fat composition.

Eighteen premature infants of similar gestational age, divided into three groups, were fed 3 milk formulas containing different amounts of linoleic acid. All the cases received 120 calories per kg of weight and day, of which formula A supplied 6.1% of the dietary total calories as linoleic acid, formula B 15.9% and formula C only 0.6%. The fatty acids of red cell ethanolamine and choline phosphoglycerides were studied in a first sample obtained during the first hours of life before the infants had received any food, and in a second sample taken at the age of three weeks. In the group fed formula C (0.6% of the total calories) changes similar to those described in EFA-deficient rats were found, namely, a decrease of linoleic acid, and an increase of oleic acid and of 20:3 (n-9), with a consequent rise of the triene to tetraene ratio. When the supply of linoleate was highest (15.9% of the total caloric intake) linoleic acid increased, oleic acid decreased and the 20:3 (n-9) practically disappeared. None of the three groups showed any clinical symptoms.     

Plasma amino acids after a feed of human milk or formula at three months of age

Prefeeding plasma amino acid concentrations were higher and glycine-to-valine ratios lower in formula-fed infants as compared to breast-fed infants at 3 months of age. After a human milk meal (true protein, 0.8 g/100 ml) or formula meal (1.5 g/100 ml), all essential and several nonessential amino acids peaked at 30-60 min. The postprandial increments were greater and lasted longer after formula, reflecting the amounts of individual amino acids in the feeds. The changes resembled those seen in adults, and were smaller than those observed in these infants at 1 week of age. These data indicate that gastrointestinal, hepatic, and endocrine responses to a meal are immature at the age of 3 months.     

CHANGES IN ERYTHROCYTE LIPID STROMA IN THE PREMATURE INFANT ACCORDING TO DIETARY FAT COMPOSITION

ABSTRACT. Eighteen premature infants of similar gestational age, divided into three groups, were fed 3 milk formulas containing different amounts of linoleic acid. All the cases received 120 calories per kg of weight and day, of which formula A supplied 6.1 % of the dietary total calories as linoleic acid, formula B 15.9% and formula C only 0.6%. The fatty acids of red cell ethanolamine and choline phosphoglycerides were studied in a first sample obtained during the first hours of life before the infants had received any food, and in a second sample taken at the age of three weeks. In the group fed formula C (0.6% of the total calories) changes similar to those described in EFA-deficient rats were found, namely, a decrease of linoleic acid, and an increase of oleic acid and of 20: 3 (n-9), with a consequent rise of the triene to tetraene ratio. When the supply of linoleate was highest (15.9% of the total caloric intake) linoleic acid increased, oleic acid decreased and the 20: 3 (n-9) practically disappeared. None of the three groups showed any clinical symptoms.     

CHANGES IN ERYTHROCYTE LIPID STROMA IN THE PREMATURE INFANT ACCORDING TO DIETARY FAT COMPOSITION

Abstract. Eighteen premature infants of similar gestational age, divided into three groups, were fed 3 milk formulas containing different amounts of linoleic acid. All the cases received 120 calories per kg of weight and day, of which formula A supplied 6.1% of the dietary total calories as linoleic acid, formula B 15.9% and formula C only 0.6%. The fatty acids of red cell ethanolamine and choline phosphoglycerides were studied in a first sample obtained during the first hours of life before the infants had received any food, and in a second sample taken at the age of three weeks. In the group fed formula C (0.6% of the total calories) changes similar to those described in EFA-deficient rats were found, namely, a decrease of linoleic acid, and an increase of oleic acid and of 20: 3 ( n -9), with a consequent rise of the triene to tetraene ratio. When the supply of linoleate was highest (15.9% of the total caloric intake) linoleic acid increased, oleic acid decreased and the 20: 3 ( n -9) practically disappeared. None of the three groups showed any clinical symptoms.     

Docosahexaenoic and arachidonic acid content of serum and red blood cell membrane phospholipids of preterm infants fed breast milk,standard formula or formula supplemented with n-3 and n-6 long-chain polyunsaturated fatty acids

The contents of docosahexaenoic (DHA) and arachidonic acid (AA) of plasma and red blood cell membrane phospholipids were studied in 41 very low birth weight infants fed either breast milk (n=18), a standard formula without long-chain polyunsaturated fatty acids with 20 or 22 carbon atoms (LCP) but with -linolenic acid and linoleic acid (n=11) or a formula additionally supplemented with n-3 and n-6 LCP in relations typical for human milk (n=12) after 2, 6, and 10 weeks of feeding. The content of DHA and AA in plasma phospholipids declined in the infants fed the LCP-free formula but remained more or less constant during the whole feeding period in those infants fed breast milk as well as in those fed the LCP-supplemented formula. The differences between the group fed the LCP-free standard formula and the two groups fed LCP-containing diets became significant during the first 2 weeks of feeding. In contrast, there were no differences between the group fed breast milk and the group fed the supplemented formula during the study period. Similar effects could be observed regarding the composition of red blood cell membrane phospholipids, but the differences between the infants fed the LCP-free standard formula and the two other groups with LCP-containing diets were significant only for AA. The data indicate that very low birth weight infants are unable to synthesize LCP from -linolenic acid and linoleic acid in sufficient amounts to prevent a decline of LCP in plasma and red blood cell phospholipids. Additionally, the data show, that supplementation of formulas with n-3 and n-6 LCP in amounts typical for human milk fat results in similar fatty acid profiles of plasma and red blood cell membrane phospholipids as found during breast milk feeding.Conclusion Supplementation of formula with long-chain polyunsaturated fatty acids improves the LCP status of very low birth weight infants.     

Fatty acid composition of the milk lipids of Fulani women and the serum phospholipids of their exclusively breast-fed infants

We previously reported that, relative to milk of women elsewhere in the world, the lipid fraction of milk of Fulani women in northern Nigeria contained relatively low proportions of alpha-linolenic acid and docosahexaenoic acid (DHA). This led us to question the essential fatty acid status of Fulani infants and the relation between the proportion of critical n-3 and n-6 fatty acids in the serum phospholipids of the mothers, their milk, and the serum phospholipids of their exclusively breast-fed infants. We were also interested in the effect de novo intermediate chain length-fatty acids (C10-C14) had on the proportions of critical and non-essential fatty acids in milk. Capillary gas-liquid chromatography was used to analyze the fatty acid content of the total milk lipids of 34 Fulani women, as well as the fatty acid content of serum phospholipids of the women and their breast-fed infants during the first 6 months of life. The proportions of critical n-3 and n-6 fatty acids in the milk of the Fulani women were adequate, but the proportions of these same fatty acids were low in their exclusively breast-fed infants. The serum phospholipids of the infants contained 18.8% linoleic acid, 0.13% alpha-linolenic acid, 12.8% arachidonic acid, and 3.40% DHA, whereas, the mean percentages of linoleic, alpha-linolenic, arachidonic and DHA in the serum phospholipids of the Fulani mothers' were 21.4, 0.20, 9.79, and 1.97, respectively. There was a strong positive correlation between fatty acid content of serum phospholipids of Fulani women and the fatty acid content of their milk lipids. As the proportion of C10-C14 fatty acids in the milk lipids increased, the proportions of critical n-3 and n-6 fatty acids in milk remained relatively constant; however, proportions of three non-essential fatty acids decreased dramatically. C10-C14 fatty acids do not appear to displace critical n-3 and n-6 fatty acids in milk.     

Fatty acid composition of plasma and red cell phospholipids of preterm babies fed on breast milk and formulae

Fatty acids of plasma and red cells of preterm babies, gestational age 28–33 weeks, weighing less than 2200 g were studied between birth and the expected date of delivery (EDD). Babies were fed either mothers' breast milk, or if they were unable, or chose not to breastfeed, randomly assigned to milk formula A or B. Milk B had 26% oleic acid, 0.5% docosahexaenoic acid (DHA) and 0.12% arachidonic (AA); A had 13% oleic acid, less than 0.05% AA and no DHA. The proportions of gamma linoleic and the other fatty acids, and the ratio of linoleic acid (LA)/alpha linolenic acid (ALA) were comparable in the two formulae. Diet and/or physiological adaptation seemed to be responsible for the significant changes in the proportions of certain fatty acids between birth and EDD. Incorporation of DHA in formula B increased its concentration in plasma and red cells, and reduced the conversion of LA to AA. With respect to maintenance of DHA status, milk B was superior to milk A but did not match breast milk.Conclusion Fortification of formula with DHA without concomitant incorporation of AA may precipitate AA insufficiency and may have developmental implications.     

Trace elements (copper, zinc, manganese, and selenium) in plasma and erythrocytes in relation to dietary intake during infancy

All determinations of copper, zinc, manganese, and selenium were performed with a flameless atomic absorption spectrophotometer. Seventy-three full-term infants aged 1 to 52 weeks were divided into three age groups. Each age group contained two subgroups, breast-fed and formula-fed. No statistically significant differences between formula-fed and breast-fed subgroups were found in regard to the levels of copper and zinc in plasma and erythrocytes. At 1 to 5 weeks of age, the manganese concentration of erythrocytes was higher in formula-fed than in breast-fed infants (p less than 0.001). This might be due to the high dietary intake of this element in the formula-fed subgroup. On the other hand, plasma selenium concentrations were significantly higher in breast-fed than in formula-fed infants of all ages (p less than 0.01 at 1 to 5 weeks and p less than 0.05 at 6 to 52 weeks). This suggests that selenium compounds are biologically more available for infant nutrition in breast milk than in formula.     

The influence of prematurity and long chain polyunsaturate supplementation in 4-week adjusted age baboon neonate brain and related tissues

Clinical studies show that docosahexaenoic acid (DHA) and arachidonic acid (ARA) supplemented formula improve visual function in preterm infants, however improved fatty acid status is known only for plasma and red blood cells (RBC) since target organs cannot be sampled from humans. Baboons were randomized to one of four groups: Term breast-fed (B); Term formula-fed (T-); Preterm formula-fed (P-); and Preterm DHA/ARA-supplemented formula-fed (P+). The P+ contained 0.61 +/- 0.03% DHA and 1.21 +/- 0.09% ARA, and breast milk had 0.68 +/- 0.22% and 0.62 +/- 0.12% as DHA and ARA, respectively. The B and P+ groups had significantly higher DHA concentration in all tissues than T- and P-. The P- group showed dramatically lower DHA content of 35%, 27%, 66%, and 75% in the brain, retina, liver, and plasma, respectively, compared with B. Supplementation prevented declines in DHA levels in the retina, and liver, and attenuated the decline in brain, plasma and RBC of preterm animals. In contrast, ARA was not significantly lower compared with B in any group in any tissue but was significantly elevated in liver and brain. RBC and plasma DHA were correlated with DHA in tissues; RBC/plasma ARA were uncorrelated with tissue ARA. We conclude that 1) DHA drops precipitously in term and preterm primates consuming formula without long chain polyunsaturates, while 22:5n-6 concentration rises; 2) tissue ARA levels are insensitive to dietary LCP supplementation or prematurity, 3) plasma and RBC levels of ARA are uncorrelated with total ARA levels; 4) DHA levels are correlated with group effects and are uncorrelated within groups.     

Docosahexaenoic acid in red blood cells of term infants receiving two levels of long-chain polyunsaturated fatty acids

OBJECTIVES: A randomized, double-blind, prospective trial assessed effects of different formula levels of polyunsaturated fatty acids on blood phospholipid docosahexaenoic (DHA; 22:6omega3) and arachidonic acids (ARA; 20:4omega6) in term infants at 120 days of age. METHODS: Healthy, formula-fed term infants (n = 78) were randomized to 1) routine milk-based formula with 8 mg DHA, 21 mg ARA, 110 mg alpha-linolenic (ALA; 18:3omega3), and 1,000 mg linoleic acids (LA; 18:2omega6) per 100 kcal (Lower-long-chain polyunsaturated fatty acids [LCPUFA]; n = 39) or 2) routine milk-based formula with 17 mg DHA, 34 mg ARA, 85 mg ALA, and 860 mg LA per 100 kcal (Higher-LCPUFA; n = 39). Fatty acid methyl esters from red blood cell (RBC) and plasma phospholipid fractions were assessed using capillary column gas chromatography. RESULTS: Compared with infants fed Lower-LCPUFA formula, the Higher-LCPUFA group had significantly greater percentages of fatty acids as DHA in RBC phosphatidylethanolamine (PE), RBC phosphatidylcholine (PC), total RBC, and plasma phospholipids (P < 0.001). Infants fed Lower-LCPUFA formula had higher percentages of precursor omega6 fatty acids in the desaturation/elongation pathway but lower percentages of ARA (RBC PE, RBC PC, and plasma phospholipid, P < 0.001; total RBC, P = 0.017) compared with the Higher-LCPUFA group. CONCLUSIONS: Greater amounts of dietary ALA do not produce as great an increase in DHA in blood lipids as preformed dietary DHA. Infants fed DHA at levels similar to human milk had significantly greater percentage of DHAat 120 days of age compared with the Lower-LCPUFA group despite higher precursor levels of ALA.