Vitamin D and Breastfeeding

Vitamin D is essential for healthy bones and growth of the skeleton and is also said to protect against autoimmune disorders, cardiovascular disease and some cancers. Vitamin D is also important for mental health and general well-being1. Deficiency can lead to developmental delay, seizures, rickets and osteomalacia (softening of the bones). Vitamin D is not really a vitamin, it is a hormone produced by the body when skin is exposed to sunlight. A small amount of vitamin D comes from our food (fatty fish, egg yolk, plus some artificially fortified margarines, breakfast cereals or yoghurts) but, as not many foods contain it, the main source is sunlight.

Vitamin D and breast milk

If a woman has sufficient vitamin D levels before and during pregnancy, her baby will be born with good vitamin D stores. After birth, these stores, combined with regular sunlight on the baby’s skin and the small amount of vitamin D in breast milk would historically provide enough of this vitamin for the breastfed baby. In recent years however, there has been a growing realisation that many women (and men) are deficient in vitamin D which can reduce both the baby’s body stores (via pregnancy) and the levels available in breast milk. This article looks at why many people are deficient in vitamin D, what this means for breast milk and the breastfed baby and discusses the recommendations for supplements for mother and baby.

Why are people deficient in vitamin D?

Our bodies make vitamin D when the skin is exposed to sunlight but because of changing lifestyles in some countries—such as limiting our time outdoors in the sun, or using a lot of sun protection—many of us are at risk of vitamin D deficiency. In the absence of enough sunlight, it’s difficult to get enough vitamin D from diet alone because not many foods contain it. Those of us who are particularly at risk of low vitamin D stores include those who:

  • Have little exposure to the sun or who cover their skin all the time with clothing or sun screen (babies often fall into this category)
  • Live further north from the equator where day light hours are reduced for example in the UK between October and March2
  • Have dark skin—more sun is needed to make the same vitamin D compared with that of a fair skinned person (NHS Choices, 2017)
  • Are obese with a body mass index (BMI) above 303.

During pregnancy

If a mother has low vitamin D levels throughout her pregnancy, her baby will also be born with low stores of this vitamin and could be at risk of deficiency. Correcting low levels during pregnancy will ensure babies are born with good stores. The Royal College of Obstetricians and Gynaecologists (RCOG) discuss recommendations for supplementation in pregnancy in Vitamin D in Pregnancy, 2014.

During breastfeeding

Breast milk has relatively low levels of vitamin D and if the mother is deficient herself, her breast milk will have even lower levels. Where babies are not getting vitamin D stores at birth, or any sun exposure on their skin for fear of sunburn or skin cancer, insufficient levels in breast milk can increase the risk of deficiency.

Raising vitamin D levels in breast milk

#1 Supplements

Research suggests that when a breastfeeding mother has high enough doses of a vitamin D dietary supplement, her breast milk will have significantly higher levels45.

What dose of vitamin D can raise levels in breast milk?

The amount of supplement required to maintain adequate levels of vitamin D in breast milk is much higher than the recommended dietary intakes generally suggested to maintain a mother’s own levels. While some studies advocate for 4000-5000 IU/day67 others state 6,400 IU/day89. Heaney compares these amounts to sun exposure:

…while 5,000–6,000 IU may initially seem high, it is important to remember how much the sun produces for us. A single 15 minute whole body exposure to sun at mid-day in summer produces well over 10,000 IU.

Balasubramanian 10 and others 1112 caution that the safety of such high-dose vitamin D supplementation in lactating women has not been proven.

The Breastfeeding Network handout states that a deficiency in vitamin D in a baby can’t be reversed by breast milk alone even if the mother starts to replenish her own deficient vitamin D status 13.

#2 Sunlight

How much sunlight is needed for an adult to make sufficient vitamin D?

Amounts of sunshine needed to ensure healthy levels of vitamin D vary due to many factors such as the amount of skin exposed, skin tone and climate. In certain latitudes there is very little sunshine for much of the year and skin tones with darker pigmentation need more exposure to reach sufficient levels. NHS Choices say “short periods” in the sun with forearms, hands or lower legs exposed without sun cream will be enough between April and September in the UK although the exact amount is unknown14. The Breastfeeding Network suggest:

Sunlight exposure needed is 2 hours per day (if only the face exposed), 20-30 minutes a day if the face, arms and neck are exposed without sunscreen. Sun protection factor in excess of 8 prevents absorption of the UVB sufficient to make vitamin D. Need increases for those with darker skins. In all cases it is important to avoid sunburn, particularly in babies.

Babies and sunlight

Direct sunlight is very powerful on a baby’s sensitive skin and the UK’s National Health Service (NHS)15 and The American Academy of Pediatrics16 recommend babies under six months old be kept out of strong direct sunlight.

Child looking up at pregnant mother in sunshine

Recommendations for breastfeeding

Recommendations for vitamin D supplementation for breastfeeding women vary between organisations even as much as a ten fold difference. Balasubramanian (2011) says:

there is no consensus on the dosage of vitamin D that needs to be supplemented to pregnant women nor is there robust scientific evidence to support implementation of a vitamin D supplementation programme for pregnant and lactating mothers.

Vitamin drops for baby or supplements for mother?

Most health recommendations currently advocate giving oral vitamin D drops to breastfed babies to ensure they are receiving enough of this vitamin. However, others such as Robert Heaney MD17 favour giving sufficient supplements to the breastfeeding mother so that mother and baby both have enough vitamin D in preference to giving vitamin drops to the baby. The Academy of Breastfeeding Medicine provides guidelines for both supplementing breastfed babies or supplementing the nursing mother in order to maximise vitamin D levels in breast milk18.

Guidance from the United Kingdom

The Scientific Advisory Committee on Nutrition (SACN) produced a new report in July 2016 upon which Public Health England (PHE) base their recommendations. They recommend 340 to 400 IU per day for all breastfed babies from birth to one year of age unless they have more than 500ml of fortified formula per day (formula is fortified with vitamin D) and 400 IU per day for a breastfeeding mother:

SACN is now recommending:

  • a reference nutrient intake (RNI) of 10 micrograms [400 IU] of vitamin D per day, throughout the year, for everyone in the general population aged 4 years and older
  • an RNI of 10 micrograms of vitamin D per day for pregnant and lactating women and population groups at increased risk of vitamin D deficiency
  • a ‘safe intake’ of 8.5 to 10 micrograms [340-400 IU] per day for all infants from birth to 1 year of age
  • a ‘safe intake’ of 10 micrograms per day for children aged 1 to 4 years.

Dr Louis Levy, Head of Nutrition Science at PHE, said:
“A healthy, balanced diet and short bursts of sunshine will mean most people get all the vitamin D they need in spring and summer. However, everyone will need to consider taking a supplement in the autumn and winter if you don’t eat enough foods that naturally contain vitamin D or are fortified with it. And those who don’t get out in the sun or always cover their skin when they do, should take a vitamin D supplement throughout the year”

Guidance from USA

The Academy of Breastfeeding Medicine recommends supplements of 400–800 IU per day for babies or 6,400 IU per day for nursing mothers to ensure a healthy vitamin D status in the breastfed baby.

The breastfeeding infant should receive vitamin D supplementation shortly after birth in doses of 10–20 μg/day (400–800 IU/day) (LOE IB). This supplement should be cholecalciferol, vitamin D3, because of superior absorption unless a vegetable source such as ergocaliferol vitamin D2, is desired (LOE IIA). Randomized trials demonstrate that safe vitamin D supplementation may be provided to a nursing mother to achieve healthy vitamin D status in her breastfeeding infant, when there is objection or contraindication to direct infant supplementation. A maternal dose of 160 μg/day (6,400 IU/day) is suggested.

The Vitamin D Council discuss their recommendations for pregnant and breastfeeding mothers and include those of The Food and Nutrition Board and The Endocrine Society in their article Vitamin D During Pregnancy and Breastfeeding. The article discusses how to take sunshine exposure into account when deciding on supplementation for the nursing mother. The Vitamin D Council recommends that if a mother is taking 6,000 IU per day as a supplement, her breast milk will have sufficient levels and she won’t need to supplement her baby. If she is not taking a supplement, or not getting good sun exposure or taking less than 5000 IU per day she should give her baby a vitamin D supplement.

The American Academy of Pediatrics (AAP) does not discuss supplements for the breastfeeding mother and recommends that all breastfed babies receive 400 IU of oral vitamin D drops, starting soon after birth:

Infants who are exclusively breastfed or receive less than 1 liter of formula daily should be supplemented with 400 IU of vitamin D daily, starting in the first few days of life and continuing until they are 12 months of age. Older children often are notoriously unpredictable eaters and also may require supplemental vitamin D. Most multivitamins provide 300-600 IU per serving.

The Health and Medicine Division (HMD) 19—previously known as The Institute of Medicine (IOM)—has a table of recommendations on their website. Their recommended dietary allowance (RDA) of vitamin D for pregnant and lactating mothers is 600 IU/day with an upper level intake of 4000 IU.

Vitamin D and the newborn’s gut

Vitamin D drops are widely recommended for babies (see above). How oral doses of vitamin drops in the early weeks of life could affect a newborn baby’s gut is not clear but Talsness et al discuss how vitamin D can affect the baby’s microbiome (balance of microorganisms living in the digestive system)20. A study by Hyppönen et al suggested babies supplemented with vitamin D during their first year of life had more allergies at age 31 years21. And Katikaneni et al found babies who had vitamin D supplements had an increased risk of urinary tract infections 22.

In addition some brands of vitamin D drops may contain multiple ingredients. Wellbaby vit D drops contain olive oil and vitamin D3 (cholecalciferol)23 while Heathy Start vitamin D drops contain vitamin A, C and D, glycerol, polysorbate 80, banana flavour, alpha-tocopherol (a type of vitamin E), and medium chain triglycerides24.

Future studies

Tan et al have described a protocol for a Cochrane review to compare the effects of giving vitamin D supplements to breastfed babies/their mothers with babies who do not have supplements or who have sun exposure25.

Summary—more research needed

Many people are deficient in vitamin D due to a general lack of sunlight in modern lifestyles. If a breastfeeding mother’s vitamin D levels are low, the levels in her breast milk will also be low. Many health organisations recommend giving vitamin D supplements to both mothers and babies as a safety measure. Some studies have indicated that providing breastfeeding mothers with specific higher doses of vitamin D ensures breast milk has sufficient levels. However, some authors believe more research is needed to evaluate the long-term effects of giving such high doses of supplement to the lactating mother. In the mean time, oral vitamin D drops are often recommended to be given direct to baby.

The need for vitamin D supplementation varies across the globe according to climate and lifestyle. The recommendations above may change as more research is revealed. Discuss the latest recommendations advised in your part of the world with your own health professionals to find the right advice for you and your baby.