Estimated reading time: 13 minutes
Updated March 2016
Diana Cassar-Uhl, MPH, IBCLC
Photo: Rachel Stein
Vitamin D is a hot topic, especially for exclusively breastfeeding families. The American Academy of Pediatrics (the AAP) recommends that families provide a vitamin D supplement for their babies regardless of how they are fed. The AAP, whose guidance is respected throughout the world, states:
“A supplement of 400 IU/day of vitamin D should begin within the first few days of life and continue throughout childhood. Any breastfeeding infant, regardless of whether he or she is being supplemented with formula, should be supplemented with 400 IU of vitamin D” (Wagner, Greer, American Academy of Pediatrics Section on Breastfeeding, & American Academy of Pediatrics Section on Nutrition, 2008).
As breastfeeding mothers and advocates, we naturally believe that breast milk, the superior infant food, confers every nutritional need our babies have, and the idea of giving our babies anything else during the first half of their first year may feel out of sync with that belief. When we turn to our trusted healthcare providers, mothers of older children, or other resources, the information we receive about vitamin D may confuse us even more.
What is vitamin D?
Even though we call it a “vitamin,” vitamin D is actually a pre-hormone we secrete that doesn’t immediately do anything, but our bodies convert it into the active hormone so it can do its various jobs. The body’s vitamin D status is measured by a test for 25-hydroxy-D 25(OH)D. (It is important to note that this is NOT the same as the test for the active hormone 1,25(OH)D, which is often elevated in people with insufficient vitamin D. If you are tested, ensure that your physician is ordering the correct test: 25(OH)D.) When we take a vitamin D supplement, it is either ergocalciferol (vitamin D2) or cholecalciferol (vitamin D3). When we are exposed to the sun, a cholesterol in our skin converts specific rays of the sun into cholecalciferol.
Why do we need vitamin D?
There is currently no consensus about exactly what vitamin D does and doesn’t do. We know vitamin D is necessary for proper calcium absorption, important for bone and dental health (since if we’re not getting enough calcium, our bodies will take what they need from our bones and teeth). Too much or not enough calcium in the body can cause more immediate problems, too, such as irregular heartbeat, loss of appetite, and a general inability to stand, walk, and function normally. We definitely know when calcium gets that far out of whack, but our bodies do such a good job of drawing it from our bones and teeth that things rarely get that serious. Sufficient vitamin D in the body helps ensure we are able to absorb and use the calcium we get from our diets.
We also know that vitamin D is necessary for beta cell function. Beta cells are the cells in our pancreas that make insulin. Insufficient vitamin D in the body may lead to problems with sugar metabolism and manifest as diabetes and insulin resistance (pre-diabetes). There is also evidence for the role of vitamin D in immune function, however, it is unclear how much vitamin D is sufficient to bolster the immune system against respiratory infections and other illnesses (Rehman, 1994; Belderbos et al., 2011; Bergman, Lindh, Bjorkhem-Bergman, & Lindh, 2013).
There is some research to suggest that insufficient vitamin D may play a part in the development of certain cancers. Insufficient vitamin D may be associated with the development of autoimmune disorders, such as rheumatoid arthritis (Christakos et al., 2013). There is emerging research that supports previous observations that higher levels of vitamin D during pre-conception and pregnancy are necessary to prevent pre-eclampsia and pre-term labor and delivery (Wagner, Taylor, & Hollis, 2010; Bener, Al-Hamaq, & Saleh, 2013).
When the Institute of Medicine prepared its guidelines for Recommended Daily Intake (RDI) of vitamin D in 2010, it could consider only the most valid and reliable studies in the research literature about vitamin D: randomized, controlled studies. Much of the published data about vitamin D was observational—not illustrative of a cause and effect relationship between vitamin D status and a particular condition—and therefore, not strong enough to define wide-sweeping public health recommendations at the time of the report’s publication. The current RDI for vitamin D for all persons between the ages of 12 months and 70 years is 600 IU/day; 800 units/day are recommended for those 70 and older and infants should take in 400 IU/day. The Institute of Medicine states that these recommendations apply to 97.5% of the population, and “are not intended to preclude individual, clinical recommendations by doctors to their patients.” Additionally, the reviewing committee acknowledged that further research—more randomized, controlled trials—is needed (U.S. Department of Health and Human Services, 2010).
How is sufficiency defined?
What is an optimal level of 25(OH) D? This is perhaps the area of greatest controversy between governmental public health guidelines and some members of the research community. For bone health, 20 ng/mL seems to be sufficient. Most people are able to achieve this 25(OH)D level by taking in 600 IU/day of vitamin D. Some suggest 32 ng/mL is optimal, while others assert that 50 ng/mL should be the minimum 25(OH)D level in humans. Still other research suggests that levels at or above 50 ng/mL can be harmful. Vitamin D toxicity—too much vitamin D—is rare, but it is possible, especially in those with such rare conditions as sarcoidosis (a chronic inflammatory condition) and Williams syndrome (a neurodevelopmental disorder).
It is worth considering that the optimal 25(OH)D level for one person may differ from that of another person. As well, arguments can be made for the biologic normalcy of a seasonal rise and fall of 25(OH)D levels. Only with additional research can the medical and science communities approach a consensus about what target 25(OH) levels should be for optimal health.
Where do we get vitamin D?
Calling vitamin D a vitamin or nutrient leads us to believe that we should get it from our diets, and this is part of the controversy over how much (or even whether) we should be adding vitamin D to our diets. Humans were designed to have their vitamin D needs satisfied through regular and frequent exposure to the sun. In lightly pigmented individuals, 15–20 minutes of full sun exposure (most skin uncovered, such as with a swimsuit on, no sunscreen, during the season when the sun’s rays are the strongest) stimulates the body’s production of 10,000-20,000 IU of vitamin D during the following 24 hours. Those with darker skin tones require longer periods of exposure, perhaps as long as an hour.
Many healthcare providers erroneously advise their patients that the daily sun exposure most of us receive year-round (hands and face while we go to and from our homes, workplaces, and cars; perhaps the occasional day outdoors) is enough for vitamin D synthesis. In many places in the world, for much of the year, the sun’s rays are not strong enough to stimulate vitamin D synthesis in our skin. Only the tropics, those areas of the planet between the 35th parallels (north and south), receive the sun’s rays year-round. For Americans, this means only those who live south of Atlanta can rely on the sun to satisfy their vitamin D needs year-round.
In addition to location, other factors can have an effect on how we receive vitamin D from the sun. For those who spend most of their lives outside of those 35th parallels, the season of the year matters. The quality of sun exposure in February will not be the same as the quality in July. Cloud cover and air pollution are variables that can change daily, as well. Obviously, when we remain indoors, the sun’s rays don’t reach us; lifestyle is definitely a factor that affects our sun exposure.
The promotion of sunscreen and clothing/ shade that minimizes the risk of skin cancer is a major public health initiative that makes sense for many people. A family’s comfort level with any unprotected exposure to the sun is important when considering whether/how much that family needs to think about vitamin D supplements. Keep in mind, also, that sun exposure for vitamin D doesn’t have to be all or nothing. A family may be comfortable with some unprotected time in the sun, and consider supplements or vitamin D-rich foods, such as fatty fish, fortified dairy products, and mushrooms to make up the rest of what they need to optimize their 25(OH)D stores.
So, what does this all mean for breastfeeding mothers?
The critical issue for breastfeeding mothers and their infants is that many mothers do not enter pregnancy or lactation with sufficient vitamin D. Two recent studies identified high percentages of pregnant women with vitamin D insufficiency—25(OH)D between 20 and 32 ng/mL, or deficiency—25(OH)D less than 20 ng/ mL (Hamilton et al., 2010 & Merewood et al., 2010). When women with low levels of vitamin D become pregnant, their babies are more likely to be born with low vitamin D, as well. However, this isn’t the only problem. A mother’s 25(OH) D level directly affects the amount of vitamin D that is transferred to her baby through her breast milk.
Recent research demonstrates that even when a mother’s vitamin D status is “sufficient,” her milk doesn’t contain the amount of vitamin D necessary to prevent rickets (and possibly other health conditions) in her baby. In the absence of adequate sun exposure, the mother requires a dose of vitamin D that is more than ten times the RDI (Wagner, 2011). While this regimen of vitamin D supplementation for mothers has been found to be effective in fortifying their breast milk with enough vitamin D to meet their babies’ needs, further research is necessary to determine that it is safe for women to take such high doses during lactation.
But I thought breast milk was the superior infant food and contained everything my baby needs?
Yes! Your milk is still the very best you can feed your baby. Perhaps in an ideal world we would all still be living in the tropics with regular exposure to the sun every day. However, if our locations and the conditions under which we live simply don’t set the stage for adequate vitamin D, then, to compensate, we need to make a conscious effort to ensure we either manufacture or take in enough vitamin D. It doesn’t just happen naturally for us when we live further away from the equator and spend most of our time indoors.
Your milk is still the very best you can feed your baby.
How do I make sure my baby is getting the vitamin D he needs to be healthy?
The answer to this question will be different for each family, but the following options may be worth considering:
Offer your baby a daily vitamin D supplement of 400 IU, in accordance with the recommendation of the American Academy of Pediatrics.
This option is ideal for those mothers and babies who cannot (because of location, season, lifestyle, or other factors) or choose not to (because of possible health risks) expose themselves to the sun on a regular basis, because it ensures the baby is receiving the recommended daily dose of vitamin D. While most pediatricians in the United States are still prescribing multi-vitamin preparations for their infant patients, regardless of how they are fed, an increasing number are becoming aware that exclusively breastfeeding mothers often prefer not to supplement their babies with vitamins and minerals that are readily available and better utilized from their own milk. If vitamin D supplementation seems like the best option for your baby, talk to your pediatrician about using a vitamin D-only preparation. These often come in tasteless, colorless, oil-based drops that can be placed on your nipple before you latch your baby on for a feeding.
Ensure the mother is replete in vitamin D.
As stated above, research supports that supplementing a mother with high doses of vitamin D is an effective—and probably safe, method of raising the amount of vitamin D that is available to a baby in mother’s milk (Wagner, 2011; Haggerty, 2011; Thiele, Senti, & Anderson, 2013). However, additional research is needed to confirm this. This option may suit the family that is uncomfortable with offering any kind of supplement, even D-only, during the time that the infant is being exclusively breastfed, and where sun exposure is not possible or desirable to the mother. It is important to consider that a mother’s 25(OH)D level may take weeks or months to increase enough that her milk offers the necessary 400 IU/day to her baby, so if she is unsure of her vitamin D status during pregnancy or immediately postpartum she should talk to her baby’s doctor about how much or how frequently to offer a supplement to her baby while she works on increasing her own stores. (This mother should keep in mind that “replete” for the purposes of conferring adequate vitamin D via breast milk may be a much higher level of 25(OH)D than is considered sufficient for other reasons.)
Expose mother, baby, or both to the sun’s rays.
In some parts of the world, it may be possible to get enough sun exposure to build robust stores of vitamin D. Lifestyle is a vital factor here: the family needs to spend enough time, unprotected, out in the sun. It is also important to consider that it is not recommended that babies be exposed to the sun without clothing, sunscreen, or other protection, because sunburn can be severe on a baby’s delicate skin, with effects that could last a lifetime.
Talk to your pediatrician about the factors that matter: your family’s skin color, family history of skin cancer, where on the globe you live, the season, and how much time you’ll be spending outdoors. Perhaps it might be safe for you to bring your baby outside wearing only his diaper for 15–20 minutes before you apply sunscreen and dress him in protective clothing and a hat. While the risks of sunburn are real for mothers, too, most adults know better how much sun exposure they can responsibly get before they burn. A mother who spends time outside daily may feel comfortable relying on the sun’s rays to sustain her vitamin D sufficiency. To be sure, a blood test (25(OH)D) can be requested, perhaps twice a year—once during the season of best exposure and again when geography or lifestyle prevents optimal sun exposure. Remember that a lab report of “normal” doesn’t necessarily represent the vitamin D status that is necessary for breast milk to confer adequate vitamin D to an infant.
Take a combination approach to vitamin D sufficiency.
Maybe you’re a family that lives within 35 degrees of the equator and likes to spend some time outside, but often it’s just too hot to be out for very long. Or, you are outside a lot, but most of your body is covered by clothing. (If only we could live at the beach and wear only our swimsuits all the time!) Perhaps you know that, in the summer, you tend to burn after more than a few minutes in the afternoon sun, and you wear a hat or sunscreen more often than not. Maybe you feel assured by the reliability of a vitamin D supplement for your baby, but you don’t remember to give it to your baby every day—and maybe you have a similar feeling (and problem) with your own supplements—you want to take the necessary daily dose to ensure your milk provides enough vitamin D to your baby, but you sometimes forget. Balancing the risks and benefits of sun exposure and supplements may require unique solutions for every family: what works for you might not be the best option for your neighbor. Do your research, consider your preferences, and talk to your baby’s doctor as you figure out the vitamin D solution that’s best for you.
Belderbos, M. E., Houben, M. L., Wilbrink, B., Lentjes, E., Bloemen, E. M., Kimpen, J. L., Rovers, M., & Bont, L. (2011). Cord blood vitamin D deficiency is associated with respiratory syncytial virus bronchiolitis. Pediatrics, 127(6),1513-1520.
Bener, A., Al-Hamaq, A. O., & Saleh, N. M. (2013). Association between vitamin D insufficiency and adverse pregnancy outcome: global comparisons. International Journal of Women’s Health, 4(5), 523- 531. doi: 10.2147/IJWH.S51403
Bergman, P., Lindh, A. U., Bjorkhem-Bergman, L., & Lindh, J. D. (2013). Vitamin D and respiratory tract infections: a systematic review and meta-analysis of randomized controlled trials. PLoS One, 8(6), e65835.
Christakos, S., Hewison, M., Gardner, et al (2013). Vitamin D: beyond bone. Annals of the New York Academy of Sciences, 1287(1), 45-58. doi: 10.1111/nyas.12129
Haggerty, L. L. (2011). Maternal supplementation for prevention and treatment of vitamin D deficiency in exclusively breastfed infants. Breastfeeding Medicine, 6(3). doi: 10.1089/bfm.2010.0025
Hamilton, S. A., McNeil, R., Hollis, B. W., et al (2010). Profound vitamin D deficiency in a diverse group
of women during pregnancy living in a sun-rich environment at latitude 32°N. International Journal of Endocrinology, 2010: 917428.doi: 10.1155/2010/917428
Merewood, A., Mehta, S. D., Grossman, X., et al (2010). Widespread vitamin D deficiency in urban Massachusetts newborns and their mothers. Pediatrics, 125(4), 640-647. doi: 10.1542/ peds.2009-2158
Rehman, P. (1994). Sub-clinical rickets and recurrent infection. Journal of Tropical Pediatrics, 40(58).
Thiele, D. K., Senti, J. L., & Anderson, C. M. (2013). Maternal vitamin D supplementation to meet the needs of the breastfed infant: a systematic review. Journal of Human Lactation, 29(2), 163-170. doi: 10.1177/0890334413477916.
U.S. Department of Health and Human Services, National Institutes of Health, Office of Dietary Supplements. (2010). Dietary supplement fact sheet: vitamin D.
Wagner, C. L., Greer, F. R., American Academy of Pediatrics Section on Breastfeeding, & American Academy of Pediatrics Section on Nutrition. (2008). Prevention of rickets and vitamin D deficiency in infants, children, and adolescents. Pediatrics, 122(5), 1142-1152. doi: 10.1542/peds.2008- 1862.
Wagner, C. L. (2011). Vitamin D recommendations during pregnancy, lactation, and early infancy. Clinical Lactation 2(1), 27-31.
Wagner, C. L., Taylor, S. N., & Hollis, B. W. (2010). New Insights Into Vitamin D During Pregnancy, Lactation, & Early Infancy. Amarillo, TX: Hale Publishing.
Diana Cassar-Uhl, MPH, IBCLC has been a La Leche League Leader in New York State, USA since 2005. A regular contributor to Breastfeeding Today, Diana is the author of La Leche League’s tear-off information sheet on Vitamin D and her writing about breastfeeding is featured on several blogs/websites, including KellyMom and The Leaky Boob. Mother to Anna (2002), Simon (2004), and Gabriella (2007), Diana served for 17 years as a clarinet player in the U.S. Army before beginning her career in public health.