The OK Daily Study

May 27, 2026 updated by: Norfolk and Norwich University Hospitals NHS Foundation Trust

Oral Vitamin K2 (Menaquinone-7; MK-7) Supplementation and Effect on Vitamin K Status of Breastfed Term Infants in Early Infancy; a Four-cohort Prospective, Part-randomised, Part-blinded Study.

The OK Daily Study is a multi-centred, part-randomised, part blinded, four cohort study. We are exploring daily dietary supplementation with vitamin K2, specifically menaquinone-7 (MK-7), given to breastfed infants or breastfeeding mothers to see whether this improves the incidence of biochemical vitamin K deficiency in the infants at 2 months postnatal age.

The overall aims are:

  • To compare infant MK-7 supplementation with placebo
  • To compare maternal MK-7 supplementation with placebo
  • To compare infant MK-7 supplementation and maternal MK-7 supplementation
  • To compare infant MK-7 supplementation with vitamin K1 supplementation via infant formula milk.

Once recruited, mother and infant pairs will be grouped initially based on the families' feeding choice. Breastfed infants will then be randomised 2:1 to the infant supplementation or maternal supplementation group. Within the infant supplementation group, infants will either receive MK-7 with vitamin D or a placebo containing vitamin D.

Follow up will occur at 2 months postnatal age (range 2-3 months postnatal age), where bloods and breastmilk samples will be collected to assess the infant and maternal vitamin K status.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

The OK Daily Study is a multi-centre study taking place in the Norfolk and Norwich University Hospital, Norwich, UK, and Ashford and St Peters' Hospital, Chertsey, UK.

Infants born at ≥37 weeks' gestation will be recruited in the participating site if they meet eligibility criteria and are born within the recruitment window. Recruitment will take place before the mother and infant are discharged from the hospital following birth.

The two main arms of this study are breastfeeding and formula feeding. Mother and infant pairs will initially be allocated based on the family's feeding preferences.

Infants in the breastfeeding arm will be randomised into group 1 or group 2 in a 2:1 ratio. Group 1 allocation will be blinded; group 2 allocation will be open label.

  • Group 1 - infant supplementation group. Infants will receive either 45 micrograms/day of MK-7 with 10 micrograms/day vitamin D3 or a placebo consisting of 10 micrograms/day vitamin D3
  • Group 2 - maternal supplementation group. Mothers in this group will receive 2 mg/day MK-7. All breastfeeding infants in this group will receive 10 micrograms/day of vitamin D3.

Formula fed infants will be in group 3 and will not require any additional supplementation as part of this study. This is because infant formula is already supplemented with adequate amounts of vitamin K1 and vitamin D.

All supplements will be started within 7 days of birth. Vitamin D drops are included for breastfed infants as per national UK guidelines.

Follow up will be as follows:

  • 1 month postnatal visit (range 1-1.5 months) - phone call.

    o Confirmation of eligibility to continue, assessment of compliance with the intervention, and to schedule the in person follow up visit

  • 2 months postnatal (range 2-3 months) - in person visit.

    • All babies will have a single blood sample taken.
    • Mothers who are in group 2 (mothers who have had MK-7 supplementation) and a selection of mothers from group 1 (breastfeeding mothers who are not supplemented with MK-7) will have a single blood sample taken and will be asked to provide a single breastmilk sample
    • Mothers will be asked about their opinions on practising the supplementation.

Blood samples will be analysed for vitamin K status, including Proteins Induced by Vitamin K Absence/antagonism of prothrombin (PIVKA-II) and of osteocalcin (undercarboxylated osteocalcin), dephosphorylated-undercarboxylated matrix gla-protein (dp-ucMGP) and serum vitamin K concentrations (including of vitamin K1 and MK-7). Breastmilk samples will be analysed for vitamin K concentrations (including vitamin K1 and MK-7)

Once this in person follow up visit has been completed, the mother and baby pair will have completed the study.

Study Type

Interventional

Enrollment (Estimated)

134

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Child

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Infants, and mothers of infants, born ≥37 weeks gestational age
  • Standard dose of intramuscular (IM) vitamin K prophylaxis given to the neonate following birth
  • For breastfeeding mothers: the mother intends to exclusively/predominantly breastfeed their baby for at least 2 months

Exclusion Criteria:

  • Inability or refusal to provide informed consent
  • Inability to adhere to or comply with study procedures
  • Babies who meet the inclusion gestation but would otherwise, as part of routine neonatal care, be provided with daily vitamin K drops (i.e. NeoKay drops) at discharge
  • IM vitamin K prophylaxis not received at birth (parents declined vitamin K prophylaxis or parents chose for neonate to receive an oral course of vitamin K prophylaxis instead)
  • Evidence of conjugated hyperbilirubinaemia (these babies are at higher risk of VKDB)
  • Mothers, and babies born to mothers, who are taking any medication that could affect or antagonise vitamin K metabolism (i.e. warfarin, the anti-epileptic drugs phenytoin or carbamazepine, and cephalosporin, rifampicin and isoniazid antimicrobials)

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Prevention
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Other: Mother and infant pairs who are breastfeeding.

Group 1 = infant supplementation group. Infants in this group will be randomised to receive either 6 drops a day containing 45 micrograms/day of MK-7 plus 10 micrograms/day vitamin D3 OR 10 micrograms/day vitamin D3 only (the active placebo, containing no vitamin K)

Group 2 = maternal supplementation group. Mothers in this group will be given 2 mg/day MK-7 capsules. Infants in this group will receive 10 micrograms/day vitamin D3.
Other: Combined MK-7 + vitamin D3 drops
6 drops/day providing 45 micrograms/day MK-7 plus 10 micrograms/day of vitamin D3
Other Names:
  • Vitamin K2 supplemented infant group
Other: Vitamin D3 Drops
6 drops/day providing 10 micrograms/day vitamin D3 and no supplementary MK-7.
Other Names:
  • Vitamin K2 unsupplemented group
Other: MK-7 capsules
1 mg capsules of menaquinone-7, with a daily dose of 2 mg (i.e. 2 capsules per day)
Active Comparator: Formula Feeding Infants
Infants who are exclusively formula feeding. These infants will receive the recommended daily amount of vitamin K through their formula milk intake and so will not receive any additional vitamin K supplementation.
Other: Vitamin D3 Drops
6 drops/day providing 10 micrograms/day vitamin D3 and no supplementary MK-7.
Other Names:
  • Vitamin K2 unsupplemented group

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Comparison of the proportion of participants who have a PIVKA-II >0.05 AU/mL in the unsupplemented and supplemented infants.
Time Frame: 2 months postnatal age (range 2-3 months).

PIVKA-II = protein induced by vitamin K antagonism/absence; clotting protein II.

Measured via serum blood sample in arbitrary units/mL. For the primary outcome, this is the comparison between the supplemented and unsupplemented infants.
2 months postnatal age (range 2-3 months).

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Comparison of the proportion of participants who have a PIVKA-II >0.05 AU/mL in the various study groups.
Time Frame: 2 months postnatal age (range 2-3 months).

PIVKA-II = protein induced by vitamin K antagonism/absence; clotting protein II.

Measured via serum blood sample in arbitrary units/mL. For secondary outcome, this is comparison between remaining groups, other than those assessed in the primary outcome measure.
2 months postnatal age (range 2-3 months).
Comparison of serum levels of osteocalcin (undercarboxylated and carboxylated) between the study groups.
Time Frame: 2 months postnatal age (range 2-3 months).
Both undercarboxylated and carboxylated levels of osteocalcin will be measured in nanograms/mL.
2 months postnatal age (range 2-3 months).
Comparison of the percentage of undercarboxylated osteocalcin as a proportion of total osteocalcin (%GluOC) between the study groups.
Time Frame: 2 months postnatal age (range 2-3 months).
Total osteocalcin calculated by the sum of the undercarboxylated and carboxylated osteocalcin values.
2 months postnatal age (range 2-3 months).
Comparison of serum levels of dephosphorylated undercarboxylated matrix Gla Protein in included participants between the study groups.
Time Frame: 2 months postnatal age (range 2-3 months).
Measured in picomol/mL
2 months postnatal age (range 2-3 months).
Comparison of levels of serum K vitamers (including, but no limited to, vitamin K1 and menaquinone-7) between the study groups.
Time Frame: 2 months postnatal age (range 2-3 months).
Serum K vitamers will be reported in micrograms/mL.
2 months postnatal age (range 2-3 months).
Comparison of the levels of breastmilk K vitamers (including, but not limited to, vitamin K1 and menaquinone-7) between unsupplemented and supplemented mothers.
Time Frame: 2 months postnatal age (range 2-3 months).
Serum K vitamers will be reported in nanograms/mL
2 months postnatal age (range 2-3 months).
Investigation of percentage compliance to study supplementation.
Time Frame: 2 months postnatal age (range 2-3 months).
Amount of remaining supplement will be assessed at follow up. This will then be used to calculate percentage compliance by comparing it to the expected volumes.
2 months postnatal age (range 2-3 months).
Investigation regarding families' opinions about infant and maternal vitamin supplementation.
Time Frame: 2 months postnatal age (range 2-3 months).
Measured via verbal questioning at follow up.
2 months postnatal age (range 2-3 months).

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Norfolk and Norwich University Hospitals NHS Foundation Trust

Collaborators

Guy's and St Thomas' NHS Foundation Trust
University of East Anglia
Maastricht University
Ashford and St. Peter's Hospitals NHS Trust

Investigators

  • Principal Investigator: Paul Clarke, Professor, Norfolk and Norwich University Hospitals Nhs Foundation Trust

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

August 1, 2026

Primary Completion (Estimated)

September 1, 2027

Study Completion (Estimated)

August 1, 2028

Study Registration Dates

First Submitted

May 13, 2026

First Submitted That Met QC Criteria

May 27, 2026

First Posted (Actual)

June 2, 2026

Study Record Updates

Last Update Posted (Actual)

June 2, 2026

Last Update Submitted That Met QC Criteria

May 27, 2026

Last Verified

May 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 150-12-25

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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