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Vitamin D supplementation in infants: why, when and how much?

Breast milk is low in vitamin D, so infants are advised to take a vitamin D supplement from birth. Turkey's practice and practical guidance.

Child Growth Scientific Board (edited by Prof. Dr. Bülent Bayraktar)May 30, 2026 1 min read

Vitamin D is essential for bone development and calcium balance. A deficiency in infants can leave bones weak and bowed (rickets). Although breast milk is ideal in many ways, it is low in vitamin D, which is why supplementation is advised.

This content is educational. Follow your pediatrician and the Turkish Ministry of Health recommendations for dose and duration.

Why supplement?

A baby's vitamin D needs aren't met sufficiently by sunlight and breast milk. Direct sun exposure isn't advised for infants' skin health. So the safe route is an oral vitamin D drop.

Practice in Turkey

Under a long-running national programme in Turkey, healthy babies are advised to receive a daily vitamin D supplement from birth/the first weeks (commonly 400 IU/day), continued through infancy. Your pediatrician and family health centre guide the exact start, dose and duration.

Breast milk or formula?

  • For exclusively breastfed babies, supplementation is clearly indicated.
  • Formula is fortified with vitamin D; but if the baby isn't taking enough per day, a supplement may still be needed. Review total intake with your doctor.

Risk of overdose

Vitamin D is fat-soluble; at very high doses it can accumulate and cause harm. So "more is better" is wrong. Stay at the recommended dose, and if you give more than one supplement (e.g. a multivitamin), check the total with your doctor.

Practical tips

  • Give the drop at the same time each day, tied to a routine feed (so you don't forget).
  • Store the bottle at room temperature and per the label.
  • Track growth regularly; if rickets is suspected (wrist/knee swelling, delayed walking, bowed legs), see your doctor.

Sources

In this series

Early Years (0–2) guide

Frequently asked questions

Who is "Vitamin D supplementation in infants: why, when and how much?" for?

It is written for families, coaches and clinicians who need a clear educational summary before deciding whether a pediatric evaluation is needed.

Does this article replace a pediatrician?

No. It is educational content. Diagnosis, treatment and urgent medical concerns should be handled by qualified clinicians.

What is the main takeaway?

Breast milk is low in vitamin D, so infants are advised to take a vitamin D supplement from birth. Turkey's practice and practical guidance.

When should families seek clinical advice?

Families should seek advice when growth velocity slows, percentiles change rapidly, puberty timing is unusual, symptoms persist, or nutrition concerns are present.

How should this content be used with calculators?

Use article context together with serial measurements and calculator warnings; do not make decisions from a single number.

#vitamin-d#infant-nutrition#rickets#0-2-years#supplement

⚕️ Medical disclaimer

The information in this article is for educational purposes only and does not constitute medical advice. For decisions about your child's growth, please consult a pediatrician or pediatric endocrinologist.