Maternal Versus Infant Vitamin DSupplementation During Lactation:A Randomized Controlled TrialBruce W. Hollis, PhDa, Carol L. Wagner, MDa, Cynthia R. Howard, MDb, Myla Ebeling, RAc, Judy R. Shary, MSa,Pamela G. Smith, BSNa, Sarah N. Taylor, MDa, Kristen Morella, MSc, Ruth A. Lawrence, MDb, Thomas C. Hulsey, ScDc

abstractOBJECTIVE: Compare effectiveness of maternal vitamin D3 supplementation with 6400 IU per dayalone to maternal and infant supplementation with 400 IU per day.

METHODS: Exclusively lactating women living in Charleston, SC, or Rochester, NY, at 4 to 6 weekspostpartum were randomized to either 400, 2400, or 6400 IU vitamin D3/day for 6 months.Breastfeeding infants in 400 IU group received oral 400 IU vitamin D3/day; infants in2400 and 6400 IU groups received 0 IU/day (placebo). Vitamin D deficiency was defined as25-hydroxy-vitamin D (25(OH)D),50 nmol/L. 2400 IU group ended in 2009 as greater infantdeficiency occurred. Maternal serum vitamin D, 25(OH)D, calcium, and phosphorusconcentrations and urinary calcium/creatinine ratios were measured at baseline then monthly,and infant blood parameters were measured at baseline and months 4 and 7.

RESULTS: Of the 334 mother-infant pairs in 400 IU and 6400 IU groups at enrollment, 216(64.7%) were still breastfeeding at visit 1; 148 (44.3%) continued full breastfeeding to 4months and 95 (28.4%) to 7 months. Vitamin D deficiency in breastfeeding infants was greatlyaffected by race. Compared with 400 IU vitamin D3 per day, 6400 IU/day safely andsignificantly increased maternal vitamin D and 25(OH)D from baseline (P , .0001). Comparedwith breastfeeding infant 25(OH)D in the 400 IU group receiving supplement, infants in the6400 IU group whose mothers only received supplement did not differ.

CONCLUSIONS:Maternal vitamin D supplementation with 6400 IU/day safely supplies breast milkwith adequate vitamin D to satisfy her nursing infant’s requirement and offers an alternatestrategy to direct infant supplementation.

WHAT’S KNOWN ON THIS SUBJECT: The vitamin Dconcentration in breast milk of women taking400 IU vitamin D per day is relatively low, leadingto vitamin D deficiency in breastfeeding infants.As a result, the American Academy of Pediatricsrecommends breastfeeding infant vitamin Dsupplementation within days after birth.

WHAT THIS STUDY ADDS: Maternal vitamin Dsupplementation alone with 6400 IU/day safelysupplies breast milk with adequate vitamin D tosatisfy the requirement of her nursing infant andoffers an alternate strategy to direct infantsupplementation.

aDivision of Neonatology, Department of Pediatrics, Medical University of South Carolina Children’s Hospital,Charleston, South Carolina; bDepartment of Pediatrics, University of Rochester, Rochester, New York; andcDepartment of Epidemiology, West Virginia University, Morgantown, West Virginia

Dr Hollis, as the principal investigator (PI) of the project, worked with Dr Wagner in theconception of the project, study design, implementation of the study, laboratory analyses, dataanalyses, and writing of the manuscript; Dr, Wagner as clinical PI of the study, worked withDrs Hollis and Howard, site PI at the University of Rochester (U of R), and all other coinvestigators inthe conception of the project, study design, implementation of the study, review of clinical andlaboratory data, subject safety, data analyses, and writing of the manuscript; Dr Howard asclinical site PI at the U of R worked directly with Dr Wagner; she was involved in the conceptionof the project, study design, implementation of the study, laboratory analyses, data analyses,and writing of the manuscript; Ms Ebeling, as Data Manager and part of the biostatistics team,was involved in all aspects of study design, data analyses, and interpretation of the data, writingof the manuscript; Ms Shary, as project manager, was involved in study design, data collection,and data analyses, as well as interpretation of the data and writing of the manuscript;

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Breast milk has long been held as the“perfect” food for the human neonatewith one caveat: it containsinsufficient vitamin D for nursingneonates to maintain minimalcirculating levels of the precursorhormone 25-hydroxy-vitamin D(25(OH)D; calcidiol), and thus skeletalintegrity.1 In fact, when comparedwith formula-fed infants, solelybreastfed infants are at increased riskof developing rickets.2,3 This isespecially true in African Americanbreastfed infants.4 Vitamin D activityin “normal” lactating women’s milk isknown to be in the range of 5 to80 IU/L depending on the methodof assay1,5,6; however, the vitamin Dcontent of human milk can be greatlyincreased by maternal oral vitamin Dsupplementation and/or increasingsolar exposure of the mother.7–9

Infants solely breastfed by womenwith vitamin D intakes of 400 IU/daytypically attain a circulating 25(OH)Dconcentration in the marginallysufficient to severely deficient(,12.5 nmol/L) range.10 Therefore,to address this risk of deficiency,supplementation of all breastfeedinginfants beginning within a few days ofbirth has been recommended by boththe American Academy of Pediatrics(AAP)11 and the Institute of Medicine(IOM).1 Although this has been therecommendation for decades, it israrely followed for various reasons,with low compliance ranging from2% to 19%,12–15 leaving the nursinginfant at significant risk for vitamin Ddeficiency.

The amount of vitamin D required bya lactating woman to normalize herown vitamin D status and ensureadequate vitamin D concentrations inher milk for her breastfeeding infantis predicted by knownpharmacokinetics about vitamin Dtransfer into human milk.7,8,16–18

Early studies demonstrated someeffectiveness of maternal vitamin Dsupplementation on increasingcirculating 25(OH)D levels in nursinginfants.7,8,16,19,20 Our research groupperformed an interventional study

providing 6400 IU vitamin D3 per dayto lactating mothers for a 6-monthperiod that produced dramaticincreases in both milk vitamin D andinfant circulating 25(OH)Dconcentrations.8 The results of thatpilot study became the basis for thislarger National Institute of ChildHealth and Human Development,2-site randomized clinical trial (RCT)using 3 maternal doses of oralvitamin D3 in a diverse group ofwomen for a 6-month period startingat 1 month postpartum. Baselinecharacteristics of the lactating motherand infant cohort have beenpublished previously.21

Our study was designed to test theprimary hypothesis that the lactatingwoman requires substantiallymore dietary vitamin D than theamount received from maternalsupplementation with 400 IU/day.1,11

We based our maternalsupplementation dosing on previousstudies: for every 1000 IU per dayvitamin D3, milk antirachitic activitywould increase by ∼80 IU/L in a waythat would sustain the nursinginfant.8,22 Thus, if successful, ourstrategy could offer an alternativeto the largely failed direct infantsupplementation strategy.1,11,14,15

The findings of this supplementationtrial are presented here.

METHODS

Design

This was a randomized, double-blind,comparative effectiveness trial of 3doses of vitamin D supplementationin lactating mothers and theirbreastfeeding infants (November2005–August 2012). The study wasconducted at the Medical Universityof South Carolina (MUSC) and theUniversity of Rochester (U of R).Approval was granted by (1) MUSC’sInstitutional Review Board forHuman Subjects HR 16536 andClinical and Translational ResearchCenter (CTRC; Protocol 752); and (2)U of R’s Institutional Review Board

(14460) and CTRC (Protocol 1129),and registered via ClinicalTrials.govNCT00412074.

Following written informed consent,mothers were randomized to 1 of 3vitamin D supplementation regimens:Group 1: 400 IU vitamin D3 per day(0 IU vitamin D3: placebo and 1 prenatalvitamin containing 400 IU vitamin D3);Group 2: 2400 IU (2000 vitamin D3 perday and 1 prenatal containing 400 IUvitamin D3); and Group 3: 6400 IUvitamin D3 per day (6000 IU vitamin D3

and 1 prenatal vitamin containing400 IU vitamin D3). Breastfeedinginfants also were given 1 drop per dayof a liquid suspension vitamin Dsupplement (Bio-D-Mulsion, BioticsResearch, Rosenberg, TX) as follows:those infants in Group 1 received 400 IUvitamin D3 as previously described,23

and infants in Groups 2 and 3 receiveda placebo emulsion containing 0 IUvitamin D3 for the 6-month study period.

Mothers and infants were evaluatedmonthly with maternal blood samplesand urine samples obtained at thosevisits. Infant urine samples wereobtained monthly but blood sampleswere drawn only at baseline (4–6weeks postpartum; V1), month 4(V4), and month 7 (V7).

Participants

Exclusively breastfeeding mothersand their singleton infants receivingno other form of nutrition other thanhuman milk at the time of studyentry24,25 within 4 to 6 weekspostpartum were eligible forinclusion in the study if theyplanned to continue exclusive/fullbreastfeeding for the next 6months.24,26 Infants had to be $35weeks’ gestation and in good generalhealth at the time of enrollment.Exclusion criteria are summarized inthe Methods section of theSupplemental information.

Outcome Measures

Laboratory Measurements

1. Maternal and infant baseline se-rum calcium and phosphorus were

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measured using standard method-ology and laboratory normativedata by MUSC’s and U of R’sClinical Chemistry Laboratories.Cross-validation between labora-tories was performed for 5%of the samples (interassay variation5.4%).

2. Circulating 25(OH)D and vitaminD (parent compound) were mea-sured using high performanceliquid chromatography andradioimmunoassay techniques aspreviously described.27–30 On thebasis of clinical laboratoryclassifications31,32 and the work ofHeaney et al33 and Vieth et al,35,36

deficiency was defined a priori astotal circulating 25(OH)D ,50nmol/L (,20 ng/mL).16,30,32,36

The inter- and intraassay co-efficient of variation was #10%(see Methods in the SupplementalInformation).

3. Maternal and Infant Circulatingintact PTH Concentrations weremeasured by immunoradiometricassay (Diasorin, Stillwater, MN).37

Statistical Methods

Sample Size and Power Considerations

One hundred and eighty-nineparticipants were to be randomizedinto 3 treatment arms, with 63 persupplementation arm substratified byrace/ethnicity. With stopping of the2400 IU arm (see Methods in theSupplemental Information fordetails), there were to be 126mother/infant pairs enrolled in thetwo remaining arms. The loss ofthe 2400 IU group (see Methods inthe Supplemental Information) didnot alter the capability of the otherarms in assessing their effectivenessbecause each can be viewed as anindependent trial.

Of the 564 women who consented toparticipate in the study, 175 women/infant pairs met exclusion criteria(Fig 1). Of the remaining women, 389women met the criterion for exclusivebreastfeeding at entrance into thestudy and had baseline 25(OH)D

concentrations measured; 55 were inthe 2400 IU group and excluded fromfinal analysis, with 334 mother/infantpairs randomized to the 400 IU and6400 IU groups. Allocation, interimanalysis, follow-up, and final analysisas well as reasons for exclusion at V4and V7 are included in Fig 1 and inthe Results section of theSupplemental Information.

Statistical Analyses

The primary outcome was changefrom baseline maternal and infanttotal circulating 25(OH)Dconcentrations at 4 and 7 monthspostpartum in exclusively/fullylactating pairs by treatment group,and the secondary outcome was thepercent of women and infants bytreatment group with 25(OH)D ,50nmol/L at baseline, 4 and 7 months’postpartum (V4 and V7).

The analysis was undertaken asintention-to-treat in which allexclusively/fully breastfeedingmothers randomized to 1 group wereconsidered to be within that groupthroughout the analysis.38

Comparison of the 3 treatmentgroups at entrance into the study wasperformed to detect potentialdifferences with regard tosociodemographic and baselineclinical characteristics (nostatistically significant differences;data not shown). After stopping the2400 IU arm due to safety concernsfor the infants (see Methods in theSupplemental Information), time-point measures were restricted to the2 remaining 400 IU and 6400 IUtreatment groups.

Statistical analyses were performedby using SAS version 9.3 (SAS, Cary,NC). Descriptive statistics were usedto characterize and compare thegroups at baseline. x2 and analysis ofvariance were used to test fordifferences in categorical data.Student’s t test analyses were used totest for differences in normallydistributed variables. The Wilcoxonrank-sum test was used for analyses

involving nonparametric variables.Regression methods (multivariateand logistic) included variables thatwere significant in bivariate analysisto model 25(OH)D status. Correlationanalysis was performed bySpearman’s correlation. Significancewas set a priori as P , .05.

RESULTS

Of the 334 women randomized intothe 400 and 6400 IU arms of thestudy who had baseline 25(OH)Dconcentration measured, 118 womenstopped exclusively breastfeedingafter randomization. Of the remaining216-exclusively/fully breastfeedingmother-infant pairs enrolled andrandomized into the 400 and 6400 IUarms of the study with baseline25(OH)D values, 148 (64.7%)continued to exclusively/fullybreastfeed and completed the studyto V4; 95 (28.4%) completed thestudy through visit 7. As shown inFig 1, the main reason for subjectattrition was change of breastfeedingstatus. Table 1 summarizes baselinesociodemographic and clinicalcharacteristics data in the 400 vs6400 IU groups of mothers who wereexclusively/fully breastfeeding at thetime of enrollment. The averagematernal dietary vitamin D intake(IU/day) was ∼200 IU/day.

Vitamin D status at baseline formother and infant by race are foundin Table 2. African American mothersand infants had substantially lowercirculating 25(OH)D levels than didwhite subjects with several minorityinfants exhibiting severe vitamin Ddeficiency (2.5 nmol/L 25(OH)D)after 1 month of breastfeeding.

Comparison of maternal and infantlaboratory parameters in the 400 IUand 6400 IU groups are found inFig 2A, 2B, 2C, and 2D (see alsoSupplemental Tables 3, 4, 5, and 6).Whereas women who wereexclusively/fully breastfeedingthrough V4 differed on baseline25(OH)D by treatment group with

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a slightly higher initial concentrationin the 6400 IU group, this differencewas not seen in the group of womenwho were exclusively/fullybreastfeeding through V7. There weresimilar numbers of women in bothtreatment groups who met the IOMdefinition of vitamin D deficiency(25(OH)D ,50 nmol/L) at baseline.The other vitamin D–related laboratoryvalues did not differ at baselinebetween the treatment groups.

By V4 there was a difference inmaternal 25(OH)D (Fig 2A) and theparent compound vitamin D but notin other parameters measured.Compared with 6400 IU group, therewas a trend with the 400 IU group atV4 being more likely to have 25(OH)Dconcentration ,50 nmol/L. In those

women who continued to fullybreastfeed through V7, significantdifferences were noted by treatmentgroup at V4 and V7 with 25(OH)D(Fig 2B) and vitamin D, andadditionally at V7 only with iPTH andserum phosphorus being lower in the6400 IU group. Within groupcomparisons of the mothers over timerevealed the following: exclusively/fully lactating women in the 400 IUgroup had –6.5 nmol/L decline in25(OH)D between V1 and V4 and –10.5nmol/L decline in 25(OH)D betweenV1 and V7 (P = .02) compared with+51.3 nmol/L in the 6400 IU groupbetween V1 and V4 that wassustained through V7 (P , .0001). Ina model predicting maternal 25(OH)Dthat included race/ethnicity,

treatment, and maternal BMI,treatment with 6400 IU was thestrongest predictor (parameterestimate 67.2 6 5.8 nmol/L; P ,.0001).

Focusing on the infants in the study,those infants fully breastfed throughV4 did not differ by treatment groupon any of the parameters measured ateither baseline or at V4 (see alsoSupplemental Tables 5 and 6). Ofnote, .70% of those babies at 1month (V1) met the IOM definition ofvitamin D deficiency (25(OH)Dconcentration ,50 nmol/L). Thoseinfants who were fully breastfedthrough V7 did not differ bytreatment group at baseline, V4 or V7on any of the parameters measuredbut there was deficiency at baseline

FIGURE 1CONSORT Flow Diagram of Study Participants throughout the Trial. CONSORT, Consolidated Standards of Reporting Trials.

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in .75% of the infants at V1. By V4,there was marked improvement thatwas sustained to V7 in bothtreatment groups. Thus, infantswhose only source of vitamin D wasmaternal (6400 IU group) did notdiffer from those infants who

received oral supplementation of 400IU/day (400 IU Group) on any of thelaboratory parameters tested. Mean25(OH)D (SD) by treatment group ofexclusively/fully breastfeedinginfants through V4 is depicted inFig 2B, and through V7 is depicted in

Fig 2D. Across the visits, there wereno differences in infant serumcalcium, creatinine, phosphorus, orurinary calcium/creatinine ratios.

When analyzed by treatment group,there were no differences in infantweight, length, and head circumferenceat any of the visits, which persistedeven after controlling for race/ethnicity (data not shown). Baselineanterior fontanelle area (AFA) did notdiffer by treatment group (seeTable 1). Maternal and infant 25(OH)Dconcentration at V1 correlated withAFA only in Hispanic infants (P , .05).At V4, there were significantdifferences between treatment groups:AFA 7.0 6 4.8 cm2 in the 400 IUgroup infants versus 3.7 6 3.7 cm2

in the 6400 IU group (P = .037).This difference was not seen in the

TABLE 1 Exclusively/Fully Breastfeeding Maternal and Infant Sociodemographic and Clinical Characteristics by Vitamin D Supplementation Group at V1

Characteristic 400 IU Group (n = 110)n (%) or Median (Range, n)

6400 IU Group (n = 106)n (%) or Median (Range, n)

P

Maternal race/ethnicity .5Black 26 (23.6) 23 (21.7)Hispanic 32 (29.1) 25 (23.6)White 52 (47.3) 58 (54.7)

Education .7Less than high school education 16 (14.6) 14 (13.2)High school graduate 22 (20.0) 17 (16.0)College or more 72 (65.5) 75 (70.8)

Employed full-time at study entrance 72 (65.5) 75 (70.8) .4Insurance .2Commercial 49 (44.6) 57 (53.8)Medicaid/none 61 (55.5) 49 (46.2)

BMI .30 28 (25.5) 21 (19.8) .3Season at study entry .5April–September 57 (51.8) 60 (56.6)October–March 53 (48.2) 46 (43.4)

Interpregnancy interval (mo) 24.0 (1.0–132.0, 83) 24.0 (1.0–156.0, 81) .4Parity 2.0 (0.0–6.0, 110) 2.0 (0.0–5.0, 106) .4Maternal Health Rating Scale 9.5 (0.0–10.0, 110) 9.00 (0.0–10.0, 106) .9Maternal age (y) 28.7 6 6.5 (18.0–48.0, 110) 29.0 6 5.8 (18.0–42.0, 106) .8Maternal wt (lb) 156.5 6 35.3 (90.6–266.1, 110) 161.2 6 30.4 (95.9–266.5, 105) .3Maternal BMI 27.8 6 5.5 (19.4–46.7, 85) 27.4 6 4.3 (19.5–40.8, 85) .6Days postpartum 37.5 6 8.6 (3.0–68.0, 110) 36.0 6 7.2 (7.0–64.0, 104) .2Maternal smart probe forearm 54.1 6 9.5 (31.7–69.2, 110) 55.0 6 9.5 (32.7–68.4, 106) .5Maternal vitamin D dietary intake (IU) 234.8 6 147.4 (29.3–562.9, 49) 201.5 6 119.1 (28.7–593.7, 59) .2Maternal Kcal intake 2378.4 6 919.0 (873.7–5220.6, 49) 2274.7 6 883.7 (806.5–5145.9, 59) .6Maternal calcium intake, mg/day 1236.2 6 522.5 (332.5–2641.5, 49) 1201.4 6 500.2 (418.2–2486.1, 59) .7Maternal baseline total circulating 25(OH)D (nmol/L) 82.1 6 31.8 (14.5–230.3, 110) 90.7 6 34.6 (20.8–191.0, 106) .06Maternal baseline total circulating vitamin D3 (nmol/L) 9.5 6 21.5 (1.5–159.5, 76) 6.4 6 10.0 (1.5–60.5, 71) .2Infant birth wt (g) 3345.6 6 475.7 (2133.0–4443.0, 110) 3460.3 6 481.1 (2370.0–4840.0, 106) .08Infant gestational age (wk) 39.3 6 1.4 (34.0–42.0, 110) 39.4 6 1.0 (36.2–41.6, 104) .5Infant fontanelle area (cm) 9.5 6 5.9 (0.8–30.0, 108) 9.8 6 6.1 (0.4–40.0, 104) .7Infant birth head circumference (cm) 37.8 6 1.3 (34.5–41.5, 110) 37.7 6 1.5 (34.0–42.0, 105) .6Infant length (cm) 54.7 6 2.4 (49.0–63.0, 110) 54.5 6 2.6 (47.0–59.5, 106) .6Infant baseline total circulating 25(OH)D (nmol/L) 33.7 6 23.5 (2.5–106.5, 110) 37.9 6 23.3 (2.5–113.8, 106) .2

TABLE 2 Baseline 25(OH)D (nmol/L)a at 1 Month Postpartum in Exclusively Breastfeeding Mothersand Infants by Race/Ethnicity Who Participated Through V4

Race/Ethnicity 25(OH)D (nmol/L), Mean 6 SD (Range)

MotherBlack/African American, n = 28 69.8 6 27.7 (26.5–132.5)Hispanic, n = 32 77.2 6 24.5 (14.5–133.3)White, n = 88 105.4 6 32.7 (47.8–230.3)

InfantBlack/African American, n = 28 24.1 6 23.1, (#2.5–113.8)b

Hispanic, n = 32 29.4 6 20.8, (#2.5–89.5)b

White, n = 88 43.4 6 22.9, (10.5–106.5)a Profound deficiency by the IOM’s Guidelines is defined as a 25(OH)D concentration ,25 nmol/L (10 ng/mL) for bothadults and children (including neonates and young infants).1b The level of detection of the assay for 25(OH)D is 2.5 nmol/L.

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subcohort of infants who continued tobreastfeed through V7.

The number of adverse events andserious adverse events did not differby treatment group. There were 7adverse events among thebreastfeeding mothers/infantsequally distributed by treatmentgroup. The Data and SafetyMonitoring Committee (DSMC)deemed these events as not beingrelated to treatment dose.

DISCUSSION

In this study of 3 dosing schedules inlactating women and theirexclusively/fully breastfeedinginfants, maternal supplementation

with 6400 IU vitamin D3/day wassuperior to either 2400 IU or 400 IU/day in safely achieving robustmaternal vitamin D sufficiency thatallowed sufficient vitamin D transferin the breast milk for infant vitamin Dsufficiency for the 6-month studyperiod. Thus, when compared withinfants receiving a daily oral vitaminD supplement of 400 IU/day, infantswhose mothers were taking 6400 IUvitamin D daily (as their sole sourceof vitamin D) achieved equivalentvitamin D status. With appropriatevitamin D intake, the lactating mothercan fully transfer from her blood toher milk the vitamin D required tosustain optimal vitamin D nutrition inthe nursing infant with no additional

supplementation required for theinfant.8 Furthermore, the safetyprofiles of women in each treatmentgroup were equivalent. As viewed bythe DSMC, there were no instances ofadverse events attributable to vitaminD supplementation.

When this study was initiated, theIOM upper limit for vitamin D was2000 IU per day.39 An InvestigationalNew Drug application to the US Foodand Drug Administration wasmandated to conduct both the currentstudy and our pregnancy vitamin Dsupplementation trials.40,41 Since thattime, the IOM has increased the upperlimit to 4000 IU per day,1 and theEndocrine Society set the upper limitat 10 000 IU/day.42 During the past

FIGURE 2Total circulating 25(OH)D concentration (nmol/L) by treatment (400 IU vs 6400 IU groups) of breastfeeding mothers: A, through V4; B, through V7; and ofbreastfeeding infants: C, through V4; D, through V7.

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decade several studies, including ourown, were performed using ouroriginal Food and DrugAdministration Investigational NewDrug application involving severalthousand patients. To our knowledge,not a single adverse event hasbeen attributed to vitamin Dsupplementation at the doses rangingfrom 2000 to 6400 IU/day.

It is universally accepted thatvitamin D toxicity is associated withhypercalciuria, hypercalcemia, andrisk of renal stones.1 In 2006,Jackson et al43 published theWomen’s Health Initiative study thatclaimed an adjusted vitamin Dintake of 280 IU per day resulted inan increase in renal stone incidence.These findings are in markedcontrast to the results of a recentreport involving several thousandsubjects consuming up to 10 000 IUvitamin D per day for 1.5 years thatdemonstrated no relationship withrenal stones.44 In our studies, wehave never observed an event ofhypercalciuria associated withvitamin D intake or circulating levelsof 25(OH)D.7,8,40,41 Concern remainsabout vitamin D toxicity as it relatesto mortality.45 A recent meta-analysis by Garland et al on thesubject, however, clearlydemonstrated increased all-causemortality at low circulating levelswith no such relationship at higherlevels.467 Finally, the levels ofcirculating 25(OH)D we report hereare robust and consistent with levelsachieved in various populationsinvolving only solar exposure withno dietary supplementation.47–49

Human milk has long been known tosupply inadequate amounts ofvitamin D to nutritionally support thesolely breastfed infant.1,3,11 Over thedecades, we and others have reportedthe vitamin D content of human milkand thus its antirachiticactivity.8,22,28,50–52 These studieshave provided valuable information.Universally, the antirachitic activity ofhuman milk is quite low, 5 to 80 IU/L,

unless the lactating mother isingesting a significant amount ofvitamin D daily or getting significanttotal body UV exposure.7,8,18 It is theparent compound, vitamin D itself,which overwhelmingly getstransferred into human milk from thematernal circulation.8,17,22,52,53 Thisis an important yet almost universallymisunderstood fact. Althoughcirculating vitamin D readily gainsaccess to human milk, circulating25(OH)D does not, and this transferrelationship occurs over a massiverange of vitamin D intakes and/orcirculating levels.8,22,52,53 Thus, onecannot assume that becausea lactating mother’s circulating25(OH)D level is adequate, her milkvitamin D activity will be. This isconfirmed in our baseline data(Table 1) in which mothers had beenbreastfeeding their infants for 1month. Maternal baseline circulating25(OH)D levels were quite good, ∼80to 90 nmol/L; however, infantcirculating 25(OH)D levels were inthe very low range, ∼35 nmol/L, withmany exhibiting dire deficiency,,2.5 nmol/L. This is because circulatingvitamin D3 in the mothers was low,and, in many cases, undetectable(,4 nmol/L), making mother’s milka poor source of vitamin D activity.Why? Because the circulating half-lifeof 25(OH)D is 3 to 4 weeks, and thatof vitamin D is ∼12 to 24 hours,reflecting their binding affinity tovitamin D binding protein.17 Thisreduced affinity of vitamin D3 allowsthe unbound vitamin D3 to diffuseacross cell membranes from bloodinto the milk. This concept isdiscussed in depth elsewhere.17 Thus,a daily dose of vitamin D is requiredto sustain both circulating and milklevels of vitamin D in the lactatingwoman.

From the standpoint of nature, lowvitamin D content in breast milk is anodd circumstance. Would natureallow so little vitamin D in breast milkthat the nursing infant would developrickets from ingesting it?1,3,11 We didnot believe so. Our belief was that

breast milk was deficient invitamin D due solely to lack ofsolar exposure and dietaryrecommendations for vitamin D putforth in recent decades. The currentIOM recommendation for vitamin Dintake during lactation is 400 to600 IU/d, yet historical datasuggest that this level of maternalsupplementation does nothing toincrease the vitamin D content of hermilk8,17,53 and/or support adequatenutritional vitamin D status in hernursing infant.7,8,19,52 This fact isprecisely why the AAP recommendsevery nursing infant receive a dailysupplement of 400 IU vitamin D.11

However, this last recommendationtreats only the infant and does notaddress the core problem of whybreast milk has such lowconcentrations of vitamin D. Also,the AAP recommendation11 is rarelyfollowed as evidenced by ourbaseline entry data for breastfedinfants (Table 1). In our studyinfants, only 12% were being givensupplements at baseline, whichconcurs with previous reports.12–15

This is reflected by the basecirculating 25(OH)D levels innonsupplemented infants of ∼35nmol/L following the first month ofbreastfeeding, which was less thanhalf that of the supplementedbreastfeeding infants (data notshown). This fact alone highlightshow the AAP recommendation isignored to the detriment of theinfant.

The strengths of this 2-site study arethat it was conducted at 2 distinctlatitudes with strong racial/ethnicdiversity such that the results can beapplied to a wide-range ofbreastfeeding mothers and theirinfants. Additional strengths of thestudy are that it was conducted as anRCT to assess the comparativeeffectiveness of 3 treatments.Maternal and infant laboratorymeasures further ensured the safetyof the higher dose treatment groups.Limitations of this study, however, arethat of the original enrolled women,

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64.7% at V1 and 44.3% at V4 werestill exclusively breastfeeding. Thatrate continued to decrease in theensuing months, with only 28.4% at7 months still fully breastfeeding(with the addition of complementaryfoods at 6 months). The rates ofbreastfeeding decline in the studymirrored what has been reportednationally by the Centers for DiseaseControl and Prevention.54 Thisattrition rate had been taken intoaccount in the original study design,and the number of subjects availablefor analysis at 7 months wasaccording to the sample size andpower calculations. Anotherlimitation is that although it was notpossible to measure the vitamin Dmoieties in the breast milk samplesin this study because of cost, we hadpreviously demonstrated how theparent compound vitamin D(cholecalciferol and ergocalciferol)is transferred from the mother toher milk and to her recipientinfant.7,8 With that being said,however, the most important factoris the amount of vitamin D inmother’s milk that will support thevitamin D status of her nursinginfant, which was shown to be thecase in this study.

Vitamin D deficiency is almostuniversal among solely breastfedinfants not receiving oral vitamin Dsupplementation. This problem isespecially acute in the blackpopulation.4 This issue is depicted inTable 2 in which one can see thatseveral minority infants exhibiteddire vitamin D deficiency, #2.5 nmol/Lcirculating 25(OH)D, after 1 monthof being solely breastfed. The

newborn human infant who is solelybreastfed can only acquire vitamin Dthrough direct dietarysupplementation, direct sunexposure, and/or ingestion of breastmilk. Direct supplementation is notadhered to12,13 and direct infant sunexposure is contrary to the AAP’srecommendations of no direct sunexposure during the first 6 months oflife.11,55 That leaves breast milk asthe only alternative.

The medical community hasaccepted the fact that lowconcentrations of vitamin D are aninherent defect in human milk thathas prompted the recommendation ofvitamin D supplementation forbreastfeeding infants starting withinthe first few days after birth.1,11 Thecurrent study clearly refutes thismisconception. The inherent flaw isnot the design of human milkbut in the dietary vitamin Drecommendation with respect tothe lactating mother. The currentrecommendation of 400 IU per dayto these individuals does little tosustain blood concentrations of theparent vitamin D compound, theform that crosses from the maternalcirculation into human milk; thus,minimal vitamin D is transferredinto human milk. The result: direvitamin D deficiency in thebreastfeeding infant, especiallydarker-pigmented infants. Our studyclearly demonstrates that withappropriate vitamin D intake, thelactating mother can fully transferfrom her blood to her milk thevitamin D required to sustainoptimal vitamin D nutrition in thenursing infant with no additional

supplementation required for theinfant.

ACKNOWLEDGMENTS

We thank the hundreds of womenand their infants who participatedin this clinical trial sponsored byNational Institute of Child Healthand Human Development/NationalInstitutes of Health, without whomthis study would not have beenpossible. We also thank thededication and hard work ofthe research and medical staff of theCTSA-sponsored Clinical ResearchCenters at the MUSC and the U of R.Lastly, we acknowledge BioticsResearch Corp, Rosenberg, Texas,for providing Bio-D-Mulsionvitamin D drops and Mead Johnson,Inc, Ohio (Mead Johnson, Evansville,IN), for providing vitamin D–freeformula for the infants enrolled inthe study.

ABBREVIATIONS

AAP: American Academy ofPediatrics

AFA: anterior fontanelle areaCTRC: Clinical and Translational

Research CenterDSMC: Data and Safety Monitoring

CommitteeIOM: Institute of MedicineMUSC: Medical University of South

CarolinaRCT: randomized controlled trialU of R: University of RochesterV1: Visit 1 at 1 month postpartumV4: Visit 4 at 4 months postpartumV7: Visit 7 at 7 months postpartum

Ms. Smith, as research associate, was involved in study design, data collection, and data analyses, as well as interpretation of the data and writing of the

manuscript; Dr Taylor, as a clinical coinvestigator at Medical University of South Carolina, was involved in the conception of the project, study design,

implementation of the study, laboratory analyses, data analyses, and writing of the manuscript; Ms Morella as a biostatistician as part of the biostatistics team was

involved in data analyses, interpretation of the data, and writing of the manuscript; Dr Lawrence as a clinical coinvestigator at the U of R was involved in the

conception of the project, study design, implementation of the study, laboratory analyses, data analyses, and writing of the manuscript; Dr Hulsey, as senior

coinvestigator, was involved in the conception of the project, study design, implementation of the study, laboratory analyses, data analyses, and writing of the

manuscript; and all authors approved the final manuscript as submitted.

This trial has been registered at www.clinicaltrials.gov (identifier NCT00412074); FDA Investigational New Drug approval 66,346.

632 HOLLIS et al by guest on March 21, 2020www.aappublications.org/newsDownloaded from

www.pediatrics.org/cgi/doi/10.1542/peds.2015-1669

DOI: 10.1542/peds.2015-1669

Accepted for publication Jul 27, 2015

Address all correspondence to Carol L. Wagner, MD, Medical University of South Carolina, Division of Neonatology Department of Pediatrics, 165 Ashley Ave, MSC 917,

Charleston, SC 29425. E-mail: wagnercl@musc.edu

PEDIATRICS (ISSN Numbers: Print, 0031-4005; Online, 1098-4275).

Copyright © 2015 by the American Academy of Pediatrics

FINANCIAL DISCLOSURE: The authors have indicated they have no financial relationships relevant to this article to disclose.

FUNDING: Funded in part by National Institutes of Health (NIH) 5R01HD043921, NIH RR01070, Medical University of South Carolina Department of Pediatrics, and by

the South Carolina Clinical & Translational Research (SCTR) Institute, with an academic home at the Medical University of South Carolina, NIH/National Center for

Advancing Translational Sciences grant UL1 TR000062.

POTENTIAL CONFLICT OF INTEREST: The authors have indicated they have no potential conflicts of interest to disclose.

COMPANION PAPER: A companion to this article can be found on page 763 and online at www.pediatrics.org/cgi/doi/10.1542/peds.2015-2312.

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originally published online September 28, 2015; Pediatrics C. Hulsey

Pamela G. Smith, Sarah N. Taylor, Kristen Morella, Ruth A. Lawrence and Thomas Bruce W. Hollis, Carol L. Wagner, Cynthia R. Howard, Myla Ebeling, Judy R. Shary,

Randomized Controlled TrialMaternal Versus Infant Vitamin D Supplementation During Lactation: A

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