Plasma and red blood cell folate in breastfed infants

Infant blood concentrations of folate markers and catabolites are modified by 5,10-methylenetetrahydrofolate reductase C677T genotype and dietary folate source

BACKGROUND

Folate intake and polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene may affect folate metabolism in infants.

OBJECTIVES

We investigated the association between infant's MTHFR C677T genotype, the dietary folate source, and concentrations of folate markers in the blood.

METHODS

We studied 110 breastfed infants (reference) and 182 infants who were randomly assigned to receive infant formulas enriched with either 78 μg folic acid or 81 μg (6S)-5-methyltetrahydrofolate (5-MTHF) per 100 g milk powder for 12 wk. The blood samples were available at the ages of <1 mo (baseline) and 16 wk. MTHFR genotype and concentrations of folate markers and catabolites [i.e., para-aminobenzoylglutamate (pABG)] were analyzed.

RESULTS

At baseline, carriers of the TT genotype (vs. CC) had lower mean (SD) concentrations (all in nmol/L) of red blood cell (RBC) folate [1194 (507) vs. 1440 (521), P = 0.033) and plasma pABG [5.7 (4.9) vs. 12.5 (8.1), P < 0.001] but higher plasma 5-MTHF [33.9 (16.8) vs. 24.0 (12.6), P < 0.001]. Irrespective of the genotype, infant formula with 5-MTHF (vs. folic acid) caused a significant increase in RBC folate concentration [1278 (466) vs. 947 (552), P < 0.001]. In breastfed infants, plasma concentrations of 5-MTHF and pABG increased significantly by 7.7 (20.5) and 6.4 (10.5), respectively, from baseline to 16 wk. Infant formula that complies with the present EU legislation for folate intake increased RBC folate and plasma pABG concentrations at 16 wk (P < 0.001) than formula-fed infants. At 16 wk, plasma pABG concentrations remained ∼50% lower in carriers of the TT (vs. the CC) genotype among all feeding groups.

CONCLUSIONS

Folate intake from infant formula according to the present EU legislation increased RBC folate and plasma pABG concentrations in infants to a greater extent than breastfeeding, particularly in carriers of the TT genotype. However, this intake did not completely abolish the between-genotype differences in pABG. Whether these differences have any clinical relevance, however, remains unclear. This trial was registered at clinicaltrials.gov as NCT02437721.

Assessment of different folic acid supplementation doses for low-birth-weight infants

AIM

The adequacy of 50 mcg folic acid supplementation given to low-birth-weight babies was investigated. The folate levels of the mothers and infants, and breastmilk, and the optimum dose for folic acid supplementation were also investigated.

MATERIAL AND METHODS

After obtaining blood from 141 low-birth-weight infants on the 1st day of life for serum and red cell folate levels, the infants were randomly allocated into three groups according to the folic acid supplement dose. Forty-six infants were given 25 μg/d folic acid, 39 were given 50 μg/d folic acid, and 44 were given 75 μg/d folic acid. Folic acid could not be given to 12 infants. Follow-up blood samples were obtained at the end of folic acid supplementation. Maternal samples for red cell and serum folate levels and breast milk folate levels were obtained within the first 48 hours and the samples for measuring breastmilk folate level were obtained on the 3rd day postnatally. The feeding modes of the infants, maternal folic acid intake, and details of neonate intensive care unit course were recorded.

RESULTS

The mean birth weight and gestational age of the infants were found as 1788.2±478.4 g and 33.5±2.9 weeks, respectively. The mean serum and red cell folate levels on admission were found as 21.2±12.2 ng/mL and 922.7±460.7 ng/mL, respectively. The mean maternal serum and red cell folate levels and the mean breast milk folate levels were found as 12.3±7.5 ng/mL, 845.5±301.4 ng/mL, and 30.6±33.0 ng/m, respectively. The breast milk folate levels of mothers who were supplemented with folic acid during pregnancy were significantly higher compared with mothers who were not supplemented with folic acid (p<0.001). Infants who were supplemented with folic acid had higher follow-up serum folate levels compared with the basal level in all groups, but there was no statistically significant difference between the groups.

CONCLUSION

This study showed that the folic acid doses of 25, 50, and 75 μcg/d affected serum folate levels similarly. We can conclude that the dose of 25 μcg/d is adequate for low-birth-weight infants.

5-Methyltetrahydrofolate and thiamine diphosphate in cord-blood erythrocytes of preterm versus term newborns

BACKGROUND/OBJECTIVES

A low folate or low thiamine status may be associated with the risk of preterm delivery, small for gestational age (SGA) offspring and adverse pregnancy outcomes.

SUBJECTS/METHODS

5-Methyltetrahydrofolate (5MTHF) and thiamine diphosphate (TDP) were measured directly in cord-blood erythrocytes (CBEs) of early preterm (n=26; <32 weeks gestational age; including 50% multiple births), late preterm (n=38; 32 to <37 weeks; including 24% multiple births) and term newborns (n=60, 37-42 weeks) via high-performance liquid chromatography and fluorescence detection. Associations between 5MTHF and TDP with gestational age, newborn anthropometrics (birth weight, newborn's length and head circumference) and risk of being SGA were explored.

RESULTS

Group comparison as well as multivariate linear regression analysis of cord-blood vitamins revealed that 5MTHF was significantly lower in late preterms compared with terms but did not differ between singletons and multiples. TDP tended to be higher in preterms than in terms and lower in multiples than in singletons in both early and late preterms. Multivariate analysis on birth outcomes showed that 5MTHF was significantly positively associated with gestational age, birth weight and newborn's length. 5MTHF, increasing gestational age and parity were associated with a significantly reduced risk for being SGA, while TDP, multiple births and gender were not associated with the risk for being SGA.

CONCLUSIONS

Higher CBE concentrations of 5MTHF were associated with improved birth outcomes. Lower TDP concentrations were observed in multiple births. Future studies evaluating cord-blood vitamin concentrations and their associations with birth outcomes should additionally include dietary intakes and maternal blood concentrations at different stages of pregnancy.

Vitamin requirements for term infants: considerations for infant formulae

OBJECTIVE

To provide the informed health professional with an up to date evaluation of the current thinking regarding requirements for vitamins in infant feeds. ESTABLISHING CRITERIA FOR ADEQUACY: Vitamin adequacy in the neonate is currently defined in terms of circulating levels of a vitamin or of the activity of a vitamin dependent enzyme in the erythrocytes. Although these measurements have their value there is a need to develop biochemical, physiological or clinical markers of well defined specific function. For some vitamins there is a risk of deleterious effects of very high intakes: risk of toxicity needs to be taken into consideration when making recommendations for inclusion in infant formulae. BREAST MILK AS THE 'GOLD STANDARD': Breast milk concentrations of vitamins have been used as the criteria of adequate intake by neonates. This may not always be justified. Greater consideration needs to be given to differences in bioavailability of vitamins from breast milk compared with formula feeds, of the influence of season, and of stage of lactation, on the stated composition.

EXPERIMENTAL APPROACHES

Animal studies have provided limited information regarding effects of different levels of intakes on current status indices in the neonatal period. There are few reports of randomized controlled studies into the effects of different levels of vitamins and these rely heavily on biochemical criteria of adequacy.

RECENT DEVELOPMENTS

The inclusion of beta-carotene into formula feeds for premature babies is an issue of current interest. What is the justification for this? Are there potential benefits for the term infant? Riboflavin deficiency in the period around weaning may affect the normal structural and functional development of the gastrointestinal tract; some of these effects may be permanent. RESEARCH TO BE DONE: A greater understanding of the absorption and metabolism of vitamins during infancy is required in order to help establish dietary requirements. The relative bioavailability of vitamins in human milk and formulae needs to be investigated. Criteria for vitamin adequacy should be extended to include measures of function. Information regarding the conversion factor from tryptophan to niacin in infancy would allow us to set niacin requirements with greater confidence. There is a particular lack of information about concentrations of biotin and pantothenic acid in breast milk and the relative biochemical status of infants receiving breast milk and formulae. Benefits of including beta-carotene into infant formulae need to be evaluated. The role of individual micronutrients in the structural and functional development of the gastrointestinal tract should be explored.

Folate and cobalamin status in relation to breastfeeding and weaning in healthy infants

BACKGROUND

Folate and cobalamin status changes markedly during infancy.

OBJECTIVE

We aimed to examine the influence of breastfeeding on folate and cobalamin status in healthy infants.

DESIGN

In a longitudinal study, we measured serum folate, cobalamin, holotranscobalamin, holohaptocorrin, methylmalonic acid, and homocysteine at birth and at ages 6, 12, and 24 mo (n = 361, 262, 244, and 224, respectively). Breastfeeding status and nutrient intake were assessed by using questionnaires and 7-d weighed-food records (at 12 mo).

RESULTS

All indexes changed significantly from birth to age 24 mo (P < 0.001). Folate was high until age 6 mo and then declined. At age 6 mo, folate was positively correlated with duration of exclusive breastfeeding (rho = 0.29; P < 0.001). Cobalamin status declined after birth in breastfed but increased in nonbreastfed infants. Thus, holotranscobalamin (pmol/L) was lower in breastfed than in nonbreastfed children at age 6 mo [geometric mean: 37 (95% CI: 33, 40) and 74 (64, 86), respectively], at 12 mo [51 (46, 56) and 76 (70, 82), respectively], and at 24 mo [65 (50, 83) and 90 (85, 97), respectively; P < 0.05 for all]. Complementary feeding did not increase (6 mo) or modestly increased (12 mo) cobalamin status in breastfed children. At 12 mo, cobalamin intake (microg/d), excluding breast milk cobalamin, was lower in breastfed than in nonbreastfed infants [geometric mean: 1.4 (1.3, 1.6) and 2.4 (2.1, 2.6), respectively; P < 0.001]. However, after adjustment for total cobalamin intake, cobalamin status (ie, holotranscobalamin) remained significantly lower in breastfed than in nonbreastfed infants [54 (49, 59) and 70 (64, 78), respectively; P < 0.001].

CONCLUSIONS

Low cobalamin status is a characteristic finding in breastfed children. Reference limits according to age and breastfeeding status should be considered in early childhood.

Red cell folate and plasma homocysteine in preterm infants

BACKGROUND

The supplementation of preterm infants with folic acid is routine practice in many neonatal units. However, the advent of preterm formula milks and breast milk fortifiers have increased folic acid intake. We measured red cell folate in preterm infants who received preterm formula milks and breast milk fortifiers to determine whether additional folic acid supplementation was still required. A potential benefit of folic acid supplementation is reduction of plasma total homocysteine (tHcy). tHcy appears to have a linear association with the risk of atherothrombotic vascular events in adults but its role in intraventricular haemorrhage and associated white matter damage in preterm infants is not known. As there is little information regarding tHcy in preterm infants, we also measured tHcy in this study.

METHODS

Red cell folate and tHcy were measured at 1 and 4 weeks of age and before discharge in 28 consecutive infants <34 weeks' gestation. Factors which may have affected folate and homocysteine status were recorded.

RESULTS

Red cell folate ranged between 266 and 1,513 ng/ml and deficiency (<140 ng/ml) was not observed in any sample. Red cell folate concentration tended to increase with increasing age. tHcy ranged from 0.8 to 12.2 micromol/l and fell within the 'normal' range for fasting adults.

CONCLUSIONS

Preterm formula milks and breast milk fortifiers provide sufficient folic acid to prevent folate deficiency in preterm infants. Although tHcy fell within the 'normal' range for fasting adults, more research is needed to determine optimal concentration of tHcy for preterm infants.

Exclusive breast-feeding for 6 months, with iron supplementation, maintains adequate micronutrient status among term, low-birthweight, breast-fed infants in Honduras

There is little information on the risk of micronutrient deficiencies during the period of exclusive breast-feeding. We evaluated this among term, low-birthweight (LBW; 1500-2500 g) infants in Honduras. Mother-infant pairs were recruited in the hospital and assisted with exclusive breast-feeding during the first 4 mo. At 4 mo, infants were randomly assigned to either continue exclusive breast-feeding to 6 mo (EBF; n = 59) or be given iron-fortified complementary foods (rice, chicken, fruits, and vegetables) from 4 to 6 mo while continuing to breast-feed (SF, n = 60). Blood samples were collected at 2, 4, and 6 mo and analyzed for hemoglobin (Hb), hematocrit, plasma ferritin, % transferrin saturation, vitamin A, vitamin B-12, folate, zinc, and erythrocyte folate. Infants with Hb < 100 g/L at 2 or 4 mo were given medicinal iron supplements for 2 mo; the proportion administered iron drops did not differ significantly between groups. There was no significant effect of complementary foods on indices of vitamin A, B-12, folate, or zinc status. Among infants not given medicinal iron at 4-6 mo, iron status was higher in the SF group than the EBF group. In those given medicinal iron at 4-6 mo, iron status was higher in the EBF group, suggesting that complementary foods interfered with iron utilization. About half of the infants were anemic by 2 mo, before the age when complementary foods would be recommended. This supports the recommendation that LBW infants should receive iron supplementation in early infancy. Given that infants given iron supplements did not benefit from complementary foods at 4-6 mo, we conclude that exclusive breast-feeding for 6 mo (with iron supplementation) can be recommended for term, LBW infants.

Nutrient requirements for preterm infant formulas

Achieving appropriate growth and nutrient accretion of preterm and low birth weight (LBW) infants is often difficult during hospitalization because of metabolic and gastrointestinal immaturity and other complicating medical conditions. Advances in the care of preterm-LBW infants, including improved nutrition, have reduced mortality rates for these infants from 9.6 to 6.2% from 1983 to 1997. The Food and Drug Administration (FDA) has responsibility for ensuring the safety and nutritional quality of infant formulas based on current scientific knowledge. Consequently, under FDA contract, an ad hoc Expert Panel was convened by the Life Sciences Research Office of the American Society for Nutritional Sciences to make recommendations for the nutrient content of formulas for preterm-LBW infants based on current scientific knowledge and expert opinion. Recommendations were developed from different criteria than that used for recommendations for term infant formula. To ensure nutrient adequacy, the Panel considered intrauterine accretion rate, organ development, factorial estimates of requirements, nutrient interactions and supplemental feeding studies. Consideration was also given to long-term developmental outcome. Some recommendations were based on current use in domestic preterm formula. Included were recommendations for nutrients not required in formula for term infants such as lactose and arginine. Recommendations, examples, and sample calculations were based on a 1000 g preterm infant consuming 120 kcal/kg and 150 mL/d of an 810 kcal/L formula. A summary of recommendations for energy and 45 nutrient components of enteral formulas for preterm-LBW infants are presented. Recommendations for five nutrient:nutrient ratios are also presented. In addition, critical areas for future research on the nutritional requirements specific for preterm-LBW infants are identified.

Folates and dairy products: a critical update

In recent years, folates have come into focus due to their protective role against child birth defects, for example, neural tube defects. In addition, folates may have a protective role to play against coronary heart disease and certain forms of cancer. During the last few years most countries have established increased recommended intakes of folates, for example, between 300-400 microg per day for adults. This review of folates in milk and dairy products compares some recent data based on high pressure liquid chromatography (HPLC) analyses and radioprotein-binding assays, with previous data based on microbiological assays. All three methods show similar ranges for folates in cow's milk, 5-10 microg per 100 g, the variation being due to seasonal variations. Data on folates in fermented milk (buttermilk and yogurt) are also similar for these methods. Different starter cultures, however, might explain some of the variations in folate content and folate forms. Most cheese varieties contain between 10 microg and 40 microg folate per kg, with slightly higher values for whey cheese. Ripened soft cheeses may contain up to 100 microg folate per 100 g. Most previous and recent studies using HPLC indicate that 5-methyl-tetrahydrofolate (5-methyl-THF) is the major folate form in milk, but more studies are needed concerning folate forms in other, especially fermented dairy products. Relatively new data on actual concentrations in different dairy products show folate-binding proteins (FBP) to occur in unprocessed milk, but also in pasteurised milk, spray-dried skim milk powder and whey. In contrast, UHT milk, fermented milk and most cheeses only contain low levels or trace amounts.

Thiamine, riboflavin, folate, and vitamin B12 status of low birth weight infants receiving parenteral and enteral nutrition

Thirty infants were randomly assigned to receive either 3 mL of MVI-Pediatric supplement (PAR3 group, parenterally fed) or 2 mL (PAR2 group, parenterally fed). For the first week, 100% received total parenteral nutrition (TPN), 50% by the second, and less than 33% by the third. Eighteen control infants received enteral feeds of infant formula. Baseline (before TPN) and subsequent weekly blood samples, dietary data, and 24-hour urine collections were obtained. The adequacies of thiamine and riboflavin were assessed by the thiamine pyrophosphate effect and erythrocyte glutathione reductase activity, respectively. Urinary thiamine and riboflavin levels were measured by fluorometry. Plasma folate, red blood cell folate, urinary folate, and plasma vitamin B12 concentrations were determined by radioassay. No differences between groups were observed in thiamine pyrophosphate effect, erythrocyte glutathione reductase activity, urinary B1 or B2, or red blood cell folate levels at any time. Plasma folate differed (p less than .05) among the PAR3 group (24 +/- 7 ng/mL), and both the PAR2 (13 +/- 5 ng/mL) and enterally fed (ENT) groups (16 +/- 3 ng/mL) before the initiation of feeds, at week 1 (PAR3 = 32 +/- 15 ng/mL; PAR2 = 18 +/- 4 ng/mL; ENT = 19 +/- 9, ng/mL) and between the PAR3 (30 +/- 16 ng/mL) and PAR2 (16 +/- 4 ng/mL) infants at week 2. Plasma vitamin B12 levels differed among the ENT groups (551 +/- 287 pg/mL) and both the parenteral groups (PAR2 = 841 +/- 405 pg/mL; PAR3 = 924 +/- 424 pg/mL) at week 1 and between the ENT (530 +/- 238 pg/mL) and PAR3 (999 +/- 425 pg/mL) groups at week 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of folic acid supplementation on small-for-gestational-age infants born at term

The effect of 250 micrograms folic acid (FA)/day or placebo given to 21 small-for-gestational-age infants born at term was studied during the first 3 months of life. The design of the study was double blind with random allocation. No randomization was performed in respect of breast-feeding or formula-feeding with a folate content of 60-70 micrograms/l. No significant differences were observed in haemoglobin concentration, haematocrit, weight and length between FA-supplemented and non-supplemented infants. A negative correlation was demonstrated between gestational age and erythrocyte folate (E-folate) concentration at 1 week. E-folate content was higher when no supplement was given in breast-fed than in formula-fed infants.

Serum thiamin, pyridoxal, cobalamin and folate concentrations in young infants

Blood samples were obtained from 509 apparently healthy infants between the age of 3 and 54 weeks attending for routine checks at infant health centres. Serum was assayed for thiamin, pyridoxal, cobalamin and folate. Three hundred and five infants were being breast fed and results from these were used to construct a reference range-thiamin 2-17 micrograms/l, pyridoxal 8-39 micrograms/l, cobalamin 120-800 ng/l and folate 7-47 micrograms/l (95 percentile ranges). One hundred and thirty-four infants were being fed a manufactured milk formulation and the serum concentrations of thiamin, pyridoxal and cobalamin were significantly higher than those found in breast fed infants. Thirteen infants were receiving pasteurized cow's milk. This milk was found to have more than 3 times the folate content of human breast milk yet these infants had a significantly reduced serum level of folate.

Normal vitamin requirements in neonates and infants

Information about vitamin requirements by neonates and infants has been derived from studies of the composition of breast milk, from feed-response trials, from the occurrence of overt deficiency in infants fed damaged milk formulae, and by extrapolation from experimental deficiency studies on adult humans and on animals. Our knowledge is far from complete, however, and dietary recommendations have been formulated for only about half the known vitamins in the UK. In the near future, studies with stable isotope-labelled vitamins should help to define pool sizes and turnover rates that are associated with particular intakes and thus give firmer evidence about requirements.

Plasma and red cell folate values and folate requirements in formula-fed premature infants

Plasma and red cell folate concentrations (lactobacillus casei activity) and other pertinent blood values have been studied during the 1st year of life in 41 premature infants (mean gestational age 31.6, range 26-35 weeks). They were formula-fed, 48.5 nmol (21 micrograms) folate per 1, from 1 month of age. The infants were divided into two groups according to their birth weights (BW): group A, BW less than or equal to 1750 g and group B, BW greater than 1750 g, respectively. One-half of the infants in each group received an extra 113.5 nmol (50 micrograms) folic acid daily. The premature infants were compared with 35 breast-fed term infants considered to have an optimal folate status. The infants not receiving folic acid supplementation had low plasma and red cell folate concentrations during the first months of life, while those receiving supplementation had values comparable to the breast-fed infants. No significant differences in the gain in weight and increase in length were observed when the folic acid supplemented infants in group A were compared with the non-supplemented infants. However, in the case of group B a significant increase in length and a somewhat greater weight gain were observed for infants with folic acid supplementation in comparison with those not given extra folate. No significant differences were observed between the haemoglobin, RBC and VPRC values in the folic acid supplemented and non-supplemented infants. It is estimated that the optimal folate intake during the first months of life in formula-fed premature infants is about 150 nmol (65 micrograms) per day. This amount is higher than previously recommended. The infants from all groups had a folate intake similar to, or above, the minimal daily requirement needed for erythropoiesis.

Plasma and red cell folate values and folate requirements in formula-fed term infants

Plasma and red cell folate concentrations (L. casei activity) and other pertinent blood values have been studied during the first year of life in 64 term infants. After weaning and until 6 months of age, 33 infants were given milk formula I (88 nmole [39 micrograms] folate per liter) and 31 infants MF II (178 nmole [78 micrograms] folate per liter). These infants were compared with 35 breast-fed term infants, considered to have an optimal folate status. The mean folate concentration in the human milk consumed at 3 months of age was 124 nmole (55 micrograms) per liter. The infants fed MF I had low plasma and red cell folate concentrations during the first months of life. The infants fed MF II had folate values almost comparable to those of the breast-fed infants. The weight gain in the infants fed MF II was significantly higher than observed in the infants fed MF I during the first 6 months of life. No significant differences related to folate deficiency were observed between the hemoglobin, RBC, and VPRC values in the formula-fed infants and those recorded in the breast-fed infants. It is estimated that the optimal folate intake during the first months of life in formula-fed infants is about 170 nmole (75 micrograms) per day. This amount is higher than previously recommended. Infants from all groups had folate intake similar to, or above, the minimal daily requirement needed for the erythropoiesis.

Detection of a milk factor that facilitates folate uptake by intestinal cells

Folate binding proteins in milk were tested for their effect on folate absorption. The uptake of bound folate by isolated mucosal cells from the rat small intestine was twice that of free folate and differed from it in being more effective with progression down the small intestine, in not being affected by glucose or Dilantin, in having a higher pH optimum, and in being affected by calcium concentration. This milk factor may enhance folate absorption in infants, whose risk of folate deficiency is high.

Plasma and red cell folate values in newborn infants and their mothers in relation to gestational age

The plasma and red blood cell folate concentrations have been studied in 344 newborn infants at 20 to 43 weeks of gestation and in 286 of their mothers at delivery. Folic acid supplementation was no given to the mothers during pregnancy. The mothers had no signs of folate deficiency as judged from their plasma and red blood cell folate concentrations and the red blood cell picture. The infants had significantly higher plasma folate concentrations than in adult control subjects, and six to eight times higher plasma folate concentrations than found in their mothers throughout the observation period. The red cell folate concentrations in the infants were significantly higher than in adult control subjects, and the concentrations were about two times higher than found in their mothers until 34 to 37 weeks of gestation. Term infants had significantly higher red cell folate concentrations than infants of lower gestational age. During the last weeks of pregnancy an increased transfer of folate to the fetus probably takes place.