Diagnosis and management of folate deficiency in low birthweight infants

Is folic acid supplementation really necessary in preterm infants ≤ 32 weeks of gestation?

OBJECTIVES

The aim of this study was to define whether there was folate deficiency in hospitalized preterm infants, and, second, to define the effect of feeding modalities on serum folate levels.

METHODS

Infants born ≤ 32 weeks of gestation were included in the study. Blood samples for the determination of serum folate levels were obtained on days 14 and 28 postnatally, as well as 36 weeks postconceptionally (or just before discharge if patients are discharged <36 weeks)--samples A, B, and C, respectively. Infants were divided into 3 groups based on mode of feeding; human breast milk (HBM), fortified HBM (fHBM), or preterm formula (PF).

RESULTS

A total of 162 preterm infants were enrolled: 17 (10.5%) of whom received HBM alone, 94 (58%) received fHBM, and 51 (31.5%) were fed with PF. None of the preterm infants developed folate deficiency during the study period. Preterm infants in the fHBM and PF groups had significant higher serum folate levels in samples C when compared with those receiving HBM alone (P < 0.001 for both). Multivariate analysis to evaluate the effects of maternal supplementation, smoking habit, gestational age, birth weight, and cumulative folic acid intake in samples A, B, and C suggested that maternal smoking and maternal folic acid supplementation had significant effects on serum folate levels in sample A and B.

CONCLUSIONS

Preterm infants receiving parenteral nutrition with high folic acid content have no risk of folate deficiency during the 2 months of age; however, preterm infants fed orally from birth with HBM or PF with a low folic acid content could be at risk for folate deficiency, especially when mothers are smokers and/or do not receive folic acid supplementation during pregnancy.

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.

The role of vitamins in the prevention and control of anaemia

OBJECTIVE

While iron deficiency is regarded as the major cause of nutritional anaemia, changes in vitamins A, B12, C and E, folic acid and riboflavin status have also been linked to its development and control. This paper provides a systematic review of vitamin supplementation trials relating to the control of nutritional anaemia.

METHODS

A MEDLINE search was used to find reports of vitamin supplementation trials that reported changes in anaemia or iron status.

RESULTS

Vitamin A can improve haematological indicators and enhance the efficacy of iron supplementation. Both folate and vitamin B12 can cure and prevent megaloblastic anaemia. Riboflavin enhances the haematological response to iron, and its deficiency may account for a significant proportion of anaemia in many populations. Vitamin C enhances the absorption of dietary iron, although population-based data showing its efficacy in reducing anaemia or iron deficiency are lacking. Vitamin E supplementation given to preterm infants has not reduced the severity of the anaemia of prematurity. Vitamin B6 effectively treats sideroblastic anaemia. Multivitamin supplementation may raise haemoglobin (Hb) concentration, but few studies have isolated the effect of multivitamins from iron on haematological status.

CONCLUSIONS

In general, the public health impact of vitamin supplementation in controlling anaemia is not clear. Neither are the complex interactions involving multiple vitamins in haematopoiesis sufficiently understood to explain the observed variability in haematological responses to vitamins by age, population, vitamin mixture and dosages. Further research is needed to understand the roles of individual and combined vitamin deficiencies on anaemia to design appropriate micronutrient interventions to prevent anaemia.

Thiamine, riboflavin, folate, and vitamin B12 status of infants with low birth Weights receiving enteral nutrition

The purpose of the present study was to monitor the vitamin status of 14 low-birth-weight (LBW) infants (< 1,750 g birth weight) at 2 weeks and an additional four infants at 3 weeks who were receiving an enteral formula providing 247 micrograms/100 kcal thiamine, 617 micrograms/100 kcal riboflavin, 37 micrograms/100 kcal folate, and 0.55 micrograms/100 kcal vitamin B12. The mean birth weight of the 18 infants was 1,100 +/- 259 g, and mean gestational age was 29 +/- 2 weeks. Weekly blood, 24-h urine collections, and dietary intake data were obtained. For thiamine, red blood cell (RBC) transketolase activity was within the normal range for all infants. For riboflavin, RBC glutathione reductase activity was normal for all infants except one. We calculated from intake and urinary excretion data that these infants require 225 micrograms/100 kcal thiamine and 370 micrograms/100 kcal riboflavin, respectively. Mean plasma folate levels were 21 +/- 11 ng/ml at 2 weeks and 18 +/- 5 ng/ml at 3 weeks. RBC folate levels were 455 +/- 280 ng/ml at 2 weeks and 391 +/- 168 ng/ml at 3 weeks. All folate blood values were normal, except for one subject with an elevated level (59 ng/ml). Vitamin B12 plasma values were 737 +/- 394 pg/ml at 2 weeks and 768 +/- 350 pg/ml at 3 weeks, and all values were normal except for three infants with elevated values. In conclusion, appropriate vitamin status was maintained during this short observational period, during administration of this enteral formula; however, riboflavin concentrations in the enteral feed may be excessive.

Plasma folate levels in preterm infants, with and without a 1 mg daily folate supplement

One hundred and four preterm infants were studied during the first few months of life in the Special Care Baby Unit of Addenbrooke's Hospital, Cambridge, United Kingdom. Previously, it had been the daily practice within the Unit to give a 1 mg oral supplement of folate (in the form of pteroylglutamic acid), once the infants had commenced full enteral feeding. At least one blood sample was obtained from 70 infants before oral folate supplementation was started. In these, the plasma folate levels fell progressively from a median value of 45 micrograms/l to a median of 12 micrograms/l, by the 2nd-3rd week of life. Once started on the oral supplement, 83 of the infants provided at least one blood sample. The plasma folate level of these infants rose immediately to a median value of 300 micrograms/l and a maximum of 1000 micrograms/l. Within individuals, these plasma folate levels decreased progressively following the introduction of the supplement, despite continuing daily supplementation. In a typical baby this decrease appeared to be explained by an increase in body-size, i.e. dilution of the folate into a larger pool. The implications of this level of supplementation are discussed, and in the light of our observations we suggest that daily supplementation in the range, 0.05-0.2 mg folate may be preferable for well preterm infants.

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.

Do breast and bottle fed babies require vitamin supplements?

In the present stage of knowledge, the following approach to vitamin supplementation seems reasonable. Breast-fed full-term infants should be supplemented with vitamin D (400 I.U./day). Supplementation of bottle-fed infants will depend upon the vitamin content of the formula which is being used. Pre-term and LBW infants may need higher amounts of vitamin D (800-1 000 I.U./day) and should be supplemented with vitamin E (1-2 I.U./day), C (50 mg/day), B6 (30-60 mcg/day) and folic acid (50-100 mcg/day) when they are being fed formulas with high amounts of PUFA and proteins or with iron. Multivitamin supplementation appears to be acceptable for infants of very low birth weight (less than 1 500 g) until they reach a body weight of at least 2 000 grams or a caloric intake of 300 kcal/day. Finally, the present routine of administering 0.5-1.0 mg of vitamin K at birth to all infants should be continued.

Critical vitamins for low birthweight infants

All vitamins are "critical" by definition for the growing infant. However, some of them are particularly relevant to the preterm or low birthweight (LBW) infant in whom a deficiency can occur more frequently than in a full-term newborn. In LBW infants vitamin deficiency may develop due to (1) low body stores at birth, (2) low intake, (3) limited absorption, (4) increased need or utilization, (5) presence of certain clinical conditions. The first reason concerns all lipid-soluble vitamins, and particularly vitamin E and K, which cross the placenta with some difficulty. Among hydrosoluble vitamins, cord-blood levels of vitamin B6 have been shown to be abnormally low in preterm infants. Low intake can occur because of low vitamin levels in milk or because of delayed and/or insufficient feeding. Limited intestinal absorption of vitamins in LBW infants has only been demonstrated for vitamin E and folic acid. The rapid post-natal growth may lead to increased vitamin utilization. In some clinical conditions particularly high intakes of certain vitamins are indicated. In our opinion, the really "critical" vitamins in LBW infants are vitamin D, E, K and folic acid, for which routine supplementation can be recommended, and possibly vitamins C and B6 under special circumstances.

Effect of folate deficiency on microsomal drug metabolism and heme content in the intestinal mucosa of guinea pigs

The relationship between folate deficiency, heme content, and microsomal drug metabolism in the intestinal mucosa of the guinea pig was examined. Weanling male guinea pigs were pair-fed a folate-deficient diet, and intestinal mucosal folate levels were measured. A significant decrease (75%) in these levels was observed at 3 weeks after diet initiation. A significant decrease (78%) in intestinal mucosal drug metabolism (7-ethoxycoumarin O-deethylase activity) and a significant decrease (46%) in intestinal mucosal heme content were also observed at this time. These findings indicate that folic acid deficiency in the guinea pig results in a marked reduction in heme content and microsomal drug metabolism of the intestinal mucosa.