Reports on new research published in the American Journal of Public Health1 have implied that breastfeeding may contribute to the development of rickets.2 This is a condition that affects bone development in children, causing the bones to become soft and weak, potentially leading to bone deformities (in adults rickets is known as osteomalacia or soft bones).
The report from St Michael’s Hospital, Toronto, claims that exclusive breastfeeding in the first year of life without vitamin D supplements is a known risk factor for rickets. It would seem to be difficult to draw conclusions on the relationship between the total length of time a child is breastfed and vitamin D levels, as a baby absorbs the vitamin from other food sources once complementary feeding starts.
From around the age of six months most babies will be having other foods introduced to their diets which can include vitamin D. Foods which include vitamin D are oily fish such as salmon, mackerel and sardines, as well as meat and eggs. It is also added to some breakfast cereals, soya products, dairy products, powdered milks and fat spreads. However, the changes in the way we live our lives, with less exposure to sunlight, and with the foods we eat, might mean that mothers may not have enough vitamin D in their own bodies to pass to their babies via breast milk.
Current recommendations that babies are not exposed to strong direct sunlight have also led to a decrease in their absorption of vitamin D. Breastmilk does not naturally contain high levels of Vitamin D as, in the past babies would absorb most of their Vitamin D from exposure to sunlight. However, when this is combined with a mother having low levels, it further reduces the amount that passes through breastmilk.3
Breastfeeding and Vitamin D
How much vitamin D is acquired through sunlight also depends on skin colour and where a woman resides. Those living in northern climates do not have as much chance to absorb vitamin D.
The NHS website 4 says “Most people can make enough vitamin D from being out in the sun daily for short periods with their forearms, hands or lower legs uncovered and without sunscreen from March to October, especially from 11am to 3pm. A short period of time in the sun means just a few minutes – about 10 to 15 minutes is enough for most lighter-skinned people – and is less than the time it takes you to start going red or burn. Exposing yourself for longer is unlikely to provide any additional benefits. People with darker skin will need to spend longer in the sun to produce the same amount of vitamin D.”
However, the NHS does suggest that pregnant and nursing mothers take supplements to ensure their breastmilk contains enough Vitamin D.
Do I need to take Vitamin D if I am breastfeeding?
La Leche League International says that breastfeeding mothers who have adequate amounts of vitamin D in their bodies can successfully provide enough vitamin D for their nursing children through breastmilk. However, LLLI agrees that lifestyle changes have led to some women not having enough vitamin D. They recommend that pregnant and nursing mothers obtain adequate vitamin D, or supplement as necessary. Women who aren’t sure if they need a supplement can have a simple blood test before making a choice to supplement.
Some health care professionals now recommend that infants receive vitamin D supplements in the first few days of life, but many women find it preferable to take the supplement themselves rather than trying to give it directly to the baby.
Evidence from a recent study by Professor Bruce Hollis, PhD of the Medical University of South Carolina, supports the validity of this alternative. The study found that maternal vitamin D supplementation supplied breastmilk with adequate vitamin D to satisfy the nursing infant’s requirement and offered an alternate to direct infant supplementation.5 When asked by La Leche League GB if mothers should continue to take supplements once their babies were over six months old, Professor Hollis replied: “The mother should continue to take the vitamin D as long as she is lactating.” He confirmed that part of the problem is that a lot of food does not have vitamin D in it.
Too much or too little?
If a baby is born with a deficiency in Vitamin D, due to the mother’s own low levels, this may not be reversed by the mother taking supplements.6
There is no risk of a woman’s body making too much vitamin D from sun exposure, although the usual precautions should be taken to cover or protect skin before it turns red or starts to burn. However, taking too much Vitamin D as a supplement can be harmful and a health professional should be able to give up-to-date information on recommended doses.
Breastmilk remains the optimal choice for infant nutrition. The unique structure and functions of breastmilk cannot by replicated by infant formula. It continually adapts throughout the day to suit each individual baby. The composition of human milk also changes to meet the changing needs of the baby as he matures, and even from feed to feed.
There is also evidence that the longer a baby is breastfed the greater the protection from ill health and the more positive impact on their long-term health (UNICEF 2012).7 Human milk still remains the best source of nutrition during the first year, with the appropriate introduction of complementary foods. It becomes a supplement to solids during the second year, but keeps nutritional value, as well as emotional benefits.
Low levels of Vitamin D may cause problems, not breastfeeding
While reports give the impression that breastfeeding is causing problems, the real issue is that in today’s world women may not have enough Vitamin D themselves to pass into breastmilk.
The answer is to address any possible deficiencies in that area so that babies will receive the Vitamin D they need whether this is via Vitamin D supplements and/or regular, small amounts of exposure to sunlight. Some mothers may want to ask for a medical evaluation to measure vitamin D levels in their baby’s blood. What meets the needs of one nursling may not meet the needs of another.
In January 2017 Unicef released a statement on vitamin D supplementation for breastfed babies, you can read it here.
This article was updated March 2017.
1. Darmawikarta D et al: “Total Duration of Breastfeeding, Vitamin D Supplementation, and Serum Levels of 25-Hydroxyvitamin D.”, Am J Public Health, 2016 Apr; 106 (4): 714-9.
2. Express article, “Bottle vs breast debate: Breastfed children at risk of RICKETS, says study”.
3. Vitamin D Council Website “Vitamin D during pregnancy and breastfeeding”
4. NHS Choices website “How to get vitamin D from sunlight”.
Bruce W Hollis et al: “Maternal Versus Infant Vitamin D Supplementation During Lactation: A Randomized Controlled Trial”, Pediatrics 2015, 136 (4): 625-34
5. Maternal Versus Infant Vitamin D Supplementation During Lactation: A Randomized Controlled Trial
6. Breastfeeding Network “Vitamin D and Breastfeeding”
7. Unicef “Preventing disease and saving resources:the potential contribution of increasing breastfeeding rates in the UK”