Pyridoxine supplementation of lactating mothers: relation to maternal nutrition status and vitamin B-6 concentrations in milk

Vitamin B-6 status, assessed by plasma pyridoxal phosphate (PLP) concentrations, and vitamin B-6 concentrations in breast milk were examined in 47 lactating mothers supplemented with different amounts of pyridoxine.HCl (PN.HCl) during pregnancy and the first 6 mo of lactation. PLP concentrations in cord blood and maternal plasma at 2 d postpartum and vitamin B-6 concentration in colostrum were positively correlated with the amount of PN.HCl supplementation prenatally (r = 0.71, p less than 0.001; r = 0.74, p less than 0.001; and r = 0.78, p less than 0.001, respectively). Correlations between the amounts of PN.HCl supplementation postnatally and plasma PLP concentrations increased with the length of supplementation. Plasma PLP concentrations were also correlated with vitamin B-6 concentrations of milk samples, which were obtained on the same day as plasma. PN.HCl supplements between 2.5 and 4.0 mg/d (2.1-3.4 mg PN equivalents) ensured vitamin B-6 adequacy of the mother and maintained relatively saturated concentrations of vitamin B-6 in breast milk.     

Vitamin B6 status of breast-fed infants in relation to pyridoxine HCl supplementation of mothers

The vitamin B6 nutritue of breast-fed infants was evaluated by vitamin B6 intake, plasma pyridoxal 5'-phosphate (PLP) concentration, and growth patterns during the infants' first 6 mo of age. Vitamin B6 intakes of 47 healthy, term infants were significantly correlated with four levels of maternal vitamin B6 supplements: 2.5, 4.0, 7.5, or 10.0 mg pyridoxine (PN) HCl/d and met the B6 Adequate Intake (AI, 1998) of 0.1 mg/d for infants 0 to 6 mo. Only infants whose mothers received 10.0 mg PN x HCl/d exceeded or met the Recommended Dietary Allowances (RDA, 1989) of 0.3 mg vitamin B6/d from 4 to 6 mo of age. Plasma PLP concentrations of infants, measured at 1, 4, and 6 mo of age paralleled their mother's vitamin B6 intake. Most infants showed normal growth. The findings indicated that a maternal PN x HCl supplement of 2.5 mg/d provided an adequate amount of vitamin B6 in breast milk (0.15 mg/d) for the vitamin B6 status parameters and the growth of breast-fed infants.     

Effects of vitamin B6 intake on nutriture and growth of young infants

Vitamin B6 is critical to normal development; however, the requirement for adequate nutriture of the human infant is based on limited experimental data. In this study vitamin B6 intakes of breast-fed (BF) and formula-fed (FF), healthy, term infants were related to levels of pyridoxal phosphate (PLP) in their plasma at 1, 2, 4, and 6 mo of age. Mothers of BF infants were supplemented with either 2.5 or 15.0 mg pyridoxine . hydrochloride (PN . HCl)/d. Growth was similar for FF and BF infants and was within normal ranges over the 6 mo period. Plasma PLP in cord blood was similar in BF and FF infants; however, at 1-5 d of age and at each subsequent age studied, levels of plasma PLP were significantly higher in FF infants than in BF. Lowest PLP values were for BF infants of mothers who received 2.5 mg PN . HCl/d. Mean plasma PLP decreased with age and was not correlated to vitamin B6 intakes except at 1 mo of age. At this age, vitamin B6 intake of BF infants whose mothers received 2.5 mg PN . HCl/d was only 0.1 mg B6/d. The consequences of this are uncertain; however, plasma PLP levels of the infants were low and reflected their intakes of vitamin B6.     

Effect of maternal pyridoxine X HCl supplementation on the vitamin B-6 status of mother and infant and on pregnancy outcome

The effect of maternal pyridoxine X HCl (PN-HCl) supplementation on the vitamin B-6 status of pregnant women and their infants at birth and on pregnancy outcome was investigated. Volunteer subjects were randomly assigned a daily vitamin B-6 supplement containing 0, 2.6, 5, 7.5, 10, 15 or 20 mg of PN-HCl in a double-blind study. The mean dietary vitamin B-6 intake of the group was 1.43 +/- 1.28 mg/day as estimated from 24-hour dietary recalls. Maternal plasma pyridoxal 5'-phosphate (PLP) levels were positively correlated with vitamin B-6 supplementation at 30 weeks gestation (r = 0.55, P less than 0.0005) and at delivery (r = 0.54, P less than 0.01). Cord plasma PLP levels reached a maximum when maternal PN-HCl supplementation was 7.5 mg and greater. Supplemental PN-HCl at the 7.5-mg level was required to prevent a decrease in maternal plasma PLP at delivery. Apgar scores at 1 minute after birth were higher (P less than 0.05) for infants whose mothers took 7.5 mg or more supplemental PN-HCl than for infants of mothers who took 5 mg or less. These findings indicate that a vitamin B-6 intake between 5.5 and 7.6 mg/day (diet plus supplement as pyridoxine equivalents) was required to maintain maternal plasma PLP levels at term at a level comparable to initial values.     

Pyridoxine supplementation: effect on lymphocyte responses in elderly persons

The effect of pyridoxine supplementation on lymphocyte responsiveness was investigated in 15 persons aged 65-81 y. Eleven subjects received 50 mg/d pyridoxine HCl (PN). Four subjects received a placebo. Lymphocyte proliferation to T and B cell mitogens, lymphocyte subpopulations with monoclonal antibodies, and plasma pyridoxal 5'-phosphate (PLP) were measured before and after 1 and 2 mo of supplementation. After 1 and 2 mo plasma PLP levels increased by 195 +/- 88 nM and 201 +/- 84 nM, respectively, in subjects receiving PN. With PN supplementation, lymphocyte proliferation increased significantly in response to phytohemagglutinin (p less than 0.01), pokeweed mitogen (p less than 0.01), and Staphylococcus aureus (Cowain I) (p less than 0.05). For PN-treated subjects with low presupplement plasma PLP levels, lymphocyte blastogenesis also increased significantly (p less than 0.01) in response to concanavalin A. Percentages of T3+ and T4+ but not T8+ cells increased significantly (p less than 0.05) in PN-treated subjects. These results suggest that improving vitamin B-6 status is important in stimulating immunocompetence in the elderly.     

Vitamin B-6 status of breast-fed neonates: influence of pyridoxine supplementation on mothers and neonates.

Vitamin B-6 concentrations in human milk are known to respond rapidly to changes in maternal vitamin B-6 intake. In this study, mothers were supplemented during the first 28 d of lactation with 2 or 27 mg pyridoxine (PN)-HCl/d and a subgroup of breast-fed infants of the 2-mg/d-supplemented mothers were supplemented with 0.4 mg PN-HCl/d. Vitamin B-6 intakes of breast-fed infants reflected the amount of their mother's supplement; intakes were highest for the vitamin-supplemented infants. Vitamin B-6 intake of mothers was a strong indicator of infant vitamin B-6 status. Vitamin intake of infants correlated significantly with five measures of vitamin B-6 status. Plasma pyridoxal-5'-phosphate (PLP) concentrations and birth weight were the strongest predictors of infant growth that were examined. Alkaline phosphatase activity in the mother's milk and infant plasma reflected pyridoxal-PLP ratios in these fluids, suggesting that the enzyme acts in regulating circulating vitamer concentrations.     

The effect of acute prolonged starvation on the concentrations of vitamin B6 aldehyde derivatives in whole blood

Since plasma pyridoxal-x-5'o-phosphate (PLP) levels are used to assess vitamin B6 status low levels are frequently interpreted to indicate B6 deficiency. However plasma PLP is in a dynamic equilibrium with pyridoxal (PL) through the action of non specific alkaline phosphatases (ALP). The object of this study was to monitor possible disturbances of this equilibrium in whole blood during acute prolonged fasting (40 hrs) and the subsequent repletion period in 16 healthy male dogs. Mean plasma PLP decreased by 15 percent (p less than 0.025) and PL increased by 20 percent (p less than 0.05) at the end of the starvation period and returned to baseline values after 48 hrs of refeeding. However total plasma aldehyde (PLP and PL) B6 vitamer concentrations remained unchanged throughout the investigation period. A 35 percent increase in haemolysate PL was the only significant change (p less than 0.0005) in PLP and PL levels observed in erythrocytes during fasting. It is concluded that the use of plasma PLP alone to assess vitamin B6 status may be misleading in conditions with a disturbed plasma PLP/PL equilibrium.     

Extremely low serum pyridoxal 5'-phosphate in children with familial hypophosphatemic rickets

The apparent vitamin B-6 status of 31 children with familial hypophosphatemic rickets (FHR) was determined. All children had alkaline phosphatase activity that was high-normal to elevated for their ages. A sensitive assay for pyridoxal 5'-phosphate (PLP) indicated that 15 of the 31 children had an undetectable (less than 0.2 nmol/L) concentration of the vitamer--the lowest values yet reported in human serum. The 16 remaining children had concentrations of the vitamer so low that they indicated a potential severe vitamin B-6 deficiency. However, none of the children had ever presented with any of the classical vitamin B-6-deficiency symptoms. Treatment of three additional FHR children with 100 mg pyridoxine.HCl/d resulted in a moderate and transient elevation of their serum PLP concentrations, a dramatic elevation of their erythrocyte PLP concentrations, and no improvement in clinical condition. Serum or plasma PLP concentrations are an inappropriate index for determining vitamin B-6 status in people with FHR and perhaps in others with elevated alkaline phosphatase activity.     

The measurement of plasma vitamin B6 compounds: comparison of a cation-exchange HPLC method with the open-column chromatographic method and the L-tyrosine apodecarboxylase assay

A cation-exchange high-performance liquid chromatographic (HPLC) method was found to be comparable to the open-column (OCC) method for measuring six different B6 compounds in human plasma and the L-tyrosine apodecarboxylase (LTD) assay for pyridoxal-P (PLP). Plasma samples were obtained from 9 subjects before and after 7 days of pyridoxine (PN) supplementation. PLP, pyridoxal (PL) and 4-pyridoxic acid (4-PA) were the major B6 compounds in plasma and the only compounds which increased after supplementation. The coefficients of correlation between any 2 of the 3 methods in measuring plasma PLP were greater than 0.93, and between HPLC and OCC in quantifying PL and 4-PA were 0.82 and 0.63, respectively. With the low plasma levels of pyridoxamine-P, PN and pyridoxamine, the results from OCC were consistently higher than those from HPLC. However, recoveries of spiked B6 compounds in plasma by these methods were between 84 to 105 percent for all the 5 vitamers and 4-PA.     

Effect of oral vitamin B6 supplementation on in vitro platelet aggregation

A randomized, double-blind study was conducted with 12 healthy adult males to determine the effects of oral pyridoxine supplementation on in vitro platelet aggregation. Following a 4-wk baseline period, half the subjects received 100 mg/day of pyridoxine X HCl while the remaining subjects received a placebo for 6 wk. In vitro platelet responses to ADP and collagen and the plasma pyridoxal 5'-phosphate (PLP) concentrations were measured at biweekly intervals. Plasma PLP concentrations increased significantly (p less than 0.001) for those receiving the vitamin B6 compared to baseline values or compared to those receiving the placebo. However, there was no significant effect of increased levels of plasma PLP on collagen-stimulated platelet aggregation and only a slight effect on ADP-stimulated aggregation. Acute administration of 100 mg pyridoxine X HCl failed to alter the in vitro response of platelets to either ADP or collagen. Reevaluation of conclusions based solely on in vitro studies suggesting the use of pyridoxine as an effective in vivo antithrombotic agent may be warranted.     

A new perspective in the assessment of vitamin B-6 nutritional status during pregnancy in humans

Plasma pyridoxal-5'-phosphate (PLP) concentration has been suggested as a valid indicator to assess vitamin B-6 nutritional status. Animal and human studies have shown that plasma PLP concentrations decrease progressively during pregnancy and large doses of vitamin B-6 supplementation are required to maintain plasma PLP at early or prepregnant levels. PLP is known to be hydrolyzed to pyridoxal (PL) by alkaline phosphatase (ALP), resulting in an inverse relationship between PLP and ALP. The object of this study was to compare the PLP-PL equilibrium in a group of healthy pregnant females with that of an age-matched nonpregnant control group from a similar socioeconomic background. The mean plasma PLP level was 37% lower, (P less than 0.0001), whereas the mean PL level was almost 90% higher (P less than 0.001) in the pregnant group than in the nonpregnant control group. The total amount of plasma PLP and PL levels, however, did not differ significantly (P greater than 0.24) between the two groups. Because the PL vitamer is regarded as the ultimate transport form of vitamin B-6, it may serve as a readily available source of vitamin B-6 to meet possible increased metabolic demands. Therefore, the estimation of plasma PLP alone does not permit an accurate assessment or understanding of the nutritional status and the physiology of vitamin B-6 in conditions associated with altered vitamin B-6 homeostases.     

Effects of maternal dietary restriction in vitamin B-6 on neocortex development in rats: B-6 vitamer concentrations, volume and cell estimates

Influence of the time of maternal restriction in dietary vitamin B-6 on vitamer concentrations and morphological development of neocortex was examined. Rats were fed ad libitum a vitamin B-6-free diet supplemented with 0.0 or 0.6 mg pyridoxine X hydrochloride (PN X HCl)/kg diet during gestation followed by a control diet (7.0 mg PN X HCl/kg) during lactation or were supplemented with 0.6 or 7.0 mg PN X HCl/kg diet throughout gestation and lactation. During postweaning offspring received the maternal diets fed during lactation. Neocortices of offspring were examined at 30 d of age by liquid chromatography and light microscopy. Vitamin restriction during gestation and 30 d postnatal was the only vitamin B-6-restricted treatment of the three administered that altered B-6 vitamer levels in neocortex; all vitamers were depressed equally. Brain weight and volume of neocortex were not changed significantly by the maternal restrictions imposed. However, each restriction adversely affected neurogenesis and neuron longevity of the neocortex and when expressed as percent reduction from control, neuron longevity was affected more severely than neurogenesis.     

Pyridoxal-5'-phosphate and pyridoxal biokinetics in male Wistar rats fed graded levels of vitamin B-6

Biokinetic parameters of plasma pyridoxal-5'-phosphate (PLP) and pyridoxal (PL) disposition were studied in male Wistar rats (age 8 mo) fed a purified diet containing less than 0.5, approximately 3 or approximately 6 mg pyridoxine.HCl/kg diet from weaning, with animals fed the 6 mg/kg diet serving as the control group. Basal plasma PLP concentration was lower in both the less than 0.5 and 3 mg/kg diet groups than in control animals (98 +/- 12, 314 +/- 40 and 514 +/- 56 nmol/L, respectively). Basal plasma PL concentration was lower in the less than 0.5 mg/kg diet group only [60 nmol/L (measured in pooled samples), 190 +/- 73 and 235 +/- 63 nmol/L for less than 0.5, 3 and 6 mg/kg diet groups, respectively]. In both the less than 0.5 and 3 mg/kg diet groups, PLP clearance was lower than in control rats (0.158 +/- 0.025, 0.131 +/- 0.040 and 0.240 +/- 0.051 L.h-1.kg body weight-1, respectively). In the less than 0.5 mg/kg diet group, PLP synthesis was more efficient than in control animals (34.7 +/- 9.3, 12.1 +/- 2.5 and 16.7 +/- 11.4% for less than 0.5, 3 and 6 mg/kg diet groups, respectively). In both the less than 0.5 and 3 mg/kg diet groups, volume of distribution of PLP as well as of PL was larger than in controls. It is concluded that B-6 vitamer metabolism is influenced by vitamin B-6 status. The metabolic pathway involved (PLP synthesis and/or PLP degradation) was observed to depend on degree of vitamin B-6 deficiency.     

Type 1 diabetes impairs vitamin B(6) metabolism at an early stage of women's adulthood

Vitamin B(6) (pyridoxine) metabolism in diabetes has never been investigated except for a few reports on plasma pyridoxal 5'-phosphate (PLP). These studies indicated that this most active (coenzyme) vitamer can be reduced. The present clinical investigation aimed to measure all vitamers in blood and urine by high performance liquid chromatography as well as important related factors, in women during active reproductive years. Thirty-two insulin-treated type 1 diabetic (T1D) patients, without renal complication, and 27 well-matched healthy controls, aged 30 to 40 years old, were recruited using rigorous criteria. Both groups had normal hemoglobin and serum albumin levels. Plasma PLP and pyridoxal (PL) did not differ significantly in the T1D group but alkaline phosphatase (ALP) activity was greater (p < 0.01). This produced a shift in plasma PLP-PL profile, as evidenced by a lower plasma PLP/PL ratio (p < 0.05). Enhanced ALP activity meant more PLP being dephosphorylated to PL (the membrane transfer form), with more ending up in erythrocytes to be rephosphorylated in its active form, as suggested by the significant positive correlation (p < 0.001) between plasma PL and erythrocyte PLP. More PL into blood circulation also means more oxidation of this vitamer to 4'-pyridoxic acid in kidneys, as confirmed by the positive correlation between plasma PL and urinary 4'-pyridoxic acid (p < 0.001). The positive correlation (p < 0.001) between ALP activity and glycosylated hemoglobin indicated a direct effect of the disease. The T1D-induced alteration in vitamin B(6) metabolism, consecutive to enhanced ALP activity, may put patients at greater risk of vitamin B(6) deficiency and diabetic complications.     

Vitamin B-6 requirement of growing kittens

Two experiments were conducted to determine the vitamin B-6 requirement for growing kittens. Ten kittens were divided into two groups and given a purified diet containing 8.0 mg pyridoxine (PN)/kg diet (+PN) or a PN-free diet (-PN) for 11 wk. Daily body weight gain, food intake, weekly plasma free amino acids, plasma B-6 vitamers, urinary oxalate excretion, hemoglobin (Hb) and hematocrit were measured. Kittens fed a -PN diet had depressed body weight gain, food intake, plasma pyridoxal phosphate (PLP) and pyridoxal (PL), Hb and hematocrit, and had elevated urinary oxalate, plasma tyrosine and plasma cystathionine. In a second experiment, 24 kittens were given a -PN diet for 45 d to deplete their body reserves. The kittens were then divided into six groups of four kittens each and given a purified diet containing either 0.5, 1.0, 2.0, 3.0, 4.0 or 8.0 mg PN/kg diet for 46 d. Following supplementation, positive responses in body weight gain, PLP, Hb and hematocrit, and decreased urinary oxalate excretion, plasma tyrosine and plasma cystathionine occurred in all groups except those fed 0.5 mg PN/kg diet. At the end of the repletion period, kittens fed 1.0 mg PN/kg diet had lower body weight gain, higher plasma tyrosine and cystathionine, slower rate of decrease in urinary oxalate, and lower values for Hb, hematocrit and PLP than did the kittens from groups fed 2.0-8.0 mg PN/kg diet. These findings indicate that the dietary requirement for PN is greater than 1.0 mg/kg diet, but 2.0 mg PN/kg diet is adequate for growing kittens given a 35% casein diet.     

Supplementing vitamin B6 to a low vitamin B6 diet exaggerates UVB-induced skin tumorigenesis in DMBA-treated hairless mice

7,12-Dimethylbenz[a]anthracene (DMBA)-treated hairless mice exposed to UVB radiation were used to examine the effect of graded levels of vitamin B(6) [1, 7 or 35 mg pyridoxine (PN) HCl/kg] on skin tumorigenesis for 18 wk. Compared to the 1 mg PN HCl/kg diet, the 35 mg PN HCl/kg diet significantly elevated the incidence and multiplicity of skin tumors, while there was no difference in skin tumorigenesis between the 7 and 35 mg PN HCl/kg diets. Skin levels of oxidative stress markers (lipid peroxides and protein carbonyls) were unaffected by dietary treatment. Compared to the 1 mg PN HCl/kg diet, the 7 and 35 mg PN HCl/kg diets significantly elevated serum pyridoxal 5'-phosphate (PLP) without affecting the skin level of PLP. The results suggest that dietary supplemental vitamin B(6) exaggerates UVB-induced skin tumorigenesis in hairless mice without affecting oxidative stress in the skin.     

Comparisons of uptake and cell surface binding among pyridoxal,pyridoxine, and pyridoxamine in RAW264.7 cells

ObjectiveVitamin B6 (B6) suppresses the expression of cyclooxygenase-2 stimulated by lipopolysaccharide in mouse macrophage RAW264.7 cells. The greatest effect is recognized for pyridoxal (PL) compared with pyridoxamine (PM), pyridoxine (PN), and pyridoxal 5′-phosphate (PLP). However, it has not been elucidated why PL has the strongest effect. We compared the uptakes and cell surface interactions among PL, PM, PN, and PLP in RAW264.7 cells.MethodsCyclo-oxygenase-2 mRNA expression was evaluated by real-time polymerase chain reaction. Intracellular B6 concentrations were measured by high-performance liquid chromatography. Interactions of B6s with the cell surface were analyzed using a surface plasmon resonance biosensor. B6 uptake speeds were measured using [³H]-PN.ResultsThe intracellular PLP levels did not change significantly when cells were cultured in medium containing PL, PM, PN, or PLP. Only PL interacted with the cell surface. Although PM and PN were associated with the cell surface, their binding was only recognized during sample loading. After the change to phosphate buffered saline after sample loading, the binding resonances of PM and PN returned to baseline, whereas that of PL did not. Uptake of [³H]-PN was inhibited by non-labeled PN, PL, or PLP, but not PM, at 1 μM. The inhibition rate of PL was higher than those of PN and PLP.ConclusionThe inhibition of cyclo-oxygenase-2 mRNA expression by PL may be related to the cell surface interaction of PL, rather than the intracellular PLP level. The uptake mechanism for PN and PL may differ from that for PM.     

Insensitivity of the tryptophan-load test to marginal vitamin B-6 intake in rats.

The tryptophan-load test for vitamin B-6 nutritional status was administered to adult female Long-Evans rats fed graded levels of pyridoxine hydrochloride (PN.HCl) in two experiments, and its sensitivity to marginal vitamin B-6 intake was evaluated. In Experiment 1, rats were 4-h meal-fed an AIN-76A (20% casein) diet devoid of PN.HCl for 3 wk, then repleted (n = 12) for 6 wk with 4-h pair-fed meals of either 0.25, 0.5, 1.0 or 7.0 (control) mg PN.HCl/kg diet. In Experiment 2, rats (n = 16) were pair-fed for 10 wk either 0.0, 0.5, 1.0 or 7.0 (control) mg PN.HCl/kg diet, with 24-h access to food. Vitamin B-6 nutritional status was assessed at the end of each experiment. Except in rats fed 0 mg PN.HCl/kg diet, mean body weights were not significantly different among diet groups of either experiment. Plasma pyridoxal phosphate (PLP), pyridoxal and total vitamin B-6 concentrations, determined by HPLC, were very sensitive to gradations in dietary PN.HCl concentrations (P less than 0.05). Red blood cell endogenous and PLP-stimulated alanine and aspartate aminotransferase activity did not statistically differentiate all levels of dietary vitamin B-6, although the calculated activity coefficient for each enzyme (stimulated/endogenous activity) did. Urinary xanthurenic acid excretion following a tryptophan load [24.5 mumol (5 mg) L-tryptophan/100 g body weight, injected intraperitoneally] was significantly (P less than 0.05) elevated compared with controls only in the group fed 0 mg PN/HCl/kg diet. At the tryptophan dose used here, the tryptophan-load test was not useful in detecting marginal vitamin B-6 intake in rats.     

Effect of maternal vitamin B-6 restriction on pyridoxal phosphate concentrations in developing regions of the central nervous system in rats

The effect of maternal vitamin B-6 deficiency on concentrations of pyridoxal phosphate (PLP) within four different regions of the central nervous system (CNS) of progeny, the corpus striatum (CS), hypothalamus (H), cerebellum (C), total brain and first cervical segment (C-1) of the spinal cord was determined at 7, 15, 21 and 50 days of age. PLP concentrations in each CNS region, as well as in total brain at 15, 21 and 50 days postnatally, paralleled the level of vitamin B-6 in the deficient (0.6, 0.8, 1.0 mg pyridoxine . HCl per kilogram diet) and control diets (7.0 mg pyridoxine . HCl per kilogram diet). By 21 days of age, PLP concentrations had essentially plateaued in CNS regions of controls, whereas in the vitamin B-6-restricted groups, a significant catch-up in concentration was observed between 21 and 50 days of age in all CNS regions except C-1 of the spinal cord. Throughout postnatal development, PLP concentrations in the C-1 region of spinal cord and in hypothalamus appeared least affected by vitamin B-6 restriction and levels in CS and C were most affected. These findings suggested that the mechanism for intracellular trapping of B-6 vitamers may develop in a caudal to rostral direction within the CNS.     

Adding zinc to prenatal iron and folate supplements improves maternal and neonatal zinc status in a Peruvian population.

BACKGROUND: Maternal zinc deficiency during pregnancy may be widespread among women in developing countries, but few data are available on whether prenatal zinc supplementation improves maternal and neonatal zinc status. OBJECTIVE: We studied whether maternal zinc supplementation improved the zinc status of mothers and neonates participating in a supplementation trial in a shantytown in Lima, Peru. DESIGN: Beginning at gestation week 10-24, 1295 mothers were randomly assigned to receive prenatal supplements containing 60 mg Fe and 250 microg folate, with or without 15 mg Zn. Venous blood and urine samples were collected at enrollment, at gestation week 28-30, and at gestation week 37-38. At birth, a sample of cord vein blood was collected. We measured serum zinc concentrations in 538 women, urinary zinc concentrations in 521 women, and cord zinc concentrations in 252 neonates. RESULTS: At 28-30 and 37-38 wk, mothers receiving zinc supplements had higher serum zinc concentrations than mothers who did not receive zinc (8.8 +/- 1.9 compared with 8.4 +/- 1.5 micromol/L and 8.6 +/- 1.5 compared with 8.3 +/- 1.4 micromol/L, respectively). Urinary zinc concentrations were also higher in mothers who received supplemental zinc (P < 0.05). After adjustment for covariates and confounding factors, neonates of mothers receiving zinc supplements had higher cord zinc concentrations than neonates of mothers who did not receive zinc (12.7 +/- 2.3 compared with 12.1 +/- 2.1 micromol/L). Despite supplementation, maternal and neonatal zinc concentrations remained lower than values reported for well-nourished populations. CONCLUSION: Adding zinc to prenatal iron and folate tablets improved maternal and neonatal zinc status, but higher doses of zinc are likely needed to further improve maternal and neonatal zinc status in this population.