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Sunlight and Vitamin D: Exposing the Benefits

Michelle Hottya
Santa Clarita CA USA
From: NEW BEGINNINGS, Vol. 21 No. 4, July-August 2004, p. 124

My youngest daughter recently celebrated her first birthday, a milestone often accompanied in the United States by a routine well-baby visit to the pediatrician. I knew from earlier checkups that we would be asked the usual questions of "How does the baby sleep?" "What does the baby eat?" "Is she crawling or walking?" And the new question, "Are you giving her a multi-vitamin?"

It took a bit of discussion to explain to the doctor my reasons why we have chosen not to supplement the baby's diet with vitamin drops. I had to go into detail on my research and reasons-since her primary nutrition for the first year was my milk, the doctor was concerned about the risks of a disease called "nutritional rickets."

Nutritional rickets is a preventable disease that still occurs in at-risk populations in the United States. Rickets is primarily caused by a deficiency of vitamin D. This nutrient is vitally important to the health of our bones, since it regulates the absorption of calcium into the body. Vitamin D is actually a natural hormone produced by our bodies. Its manufacture begins with exposure of the skin to the ultraviolet B (UVB) rays of the sun. Its levels are regulated by the endocrine system and it can be stored in the body for later use when UVB radiation is scarce (during winter months, for example).

However, beneficial UVB rays are blocked by clothing, sunscreen, glass, and cloud cover. These common protections, as well as other risk factors, are believed to be leading to vitamin D deficiencies in some women and young children. Since our skin requires direct exposure to the sun to receive UVB rays and synthesize vitamin D, the most efficient method of exposure is also very controversial. We have been taught over the last few decades that the sun's rays are harmful to our skin and it is now ingrained in our culture to protect our children from the sun through use of UV-filtering clothes and lotions, or by keeping them out of the sun. Research indicates that these practices are partially responsible for the occurrence of rickets in at-risk populations in the US (Shaikh & Alpert 2004). The habits we have developed to protect ourselves from skin cancer may have a negative effect on our bones.

In the early 20th century, the damaging effects of nutritional rickets were widespread in industrialized cities in the northern US and northern Europe. As agrarian societies moved into the cities to work, they spent more time indoors and gained less benefit from going out into the sun, since air pollution also blocks UV rays. To counteract rickets, dietary guidelines have been developed in various countries for recommended intake of vitamin D.

This nutrient can be absorbed from fortified foods, such as cow's milk and bread in some countries, and the livers and oil of some fatty fish. I remember my grandmother's stories of taking a teaspoon of cod liver oil every day for her health-this was a common, however unappealing, nutritional supplement in her youth.

Exclusively breastfed infants are at risk of vitamin D deficiency and rickets if their skin has inadequate exposure to UVB radiation, among other risk factors (Good Mojab 2003). Babies get their initial levels of vitamin D from their mother's stores during pregnancy. Additional vitamin D is then available through their mother's milk and via exposure of their skin to UVB radiation. The newborn's levels of vitamin D are roughly half of the mother's levels (Nesby-O'Dell et al. 2002). If the mother is vitamin D deficient during pregnancy, her baby may be at risk of congenital vitamin D deficiency. The vitamin D content of human milk varies with the mother's exposure to UVB radiation and consumption of vitamin D in her diet. When breastfed babies are exposed to biologically normal amounts of UVB radiation, they are able to maintain their own levels of vitamin D regardless of the concentration of vitamin D in their mothers' milk (Good Mojab 2004). Humans were meant to make this hormone via sunlight, not from diet alone.

Continued reports of rickets among mostly dark-skinned breastfed infants have raised the concerns of the American Academy of Pediatrics to the level of issuing a clinical report recommending measures intended to help prevent rickets. The recommended remedy-instructing parents of exclusively breastfed infants to begin giving the baby vitamin D supplements during the first two months of life-has breastfeeding advocates worried that this blanket directive will discourage mothers from breastfeeding their infants and reduce the already low rates of breastfeeding duration in the US (Heinig 2003).

The AAP's new recommendation has been in effect for over one year. Many mothers, like myself, who are dedicated to breastfeeding are facing several dilemmas: understanding the risks associated with supplementing or not supplementing; deciding whether to give the vitamin drops; and gaining support from our pediatricians for our decisions.

Since the AAP published its clinical report in the journal, Pediatrics, many pediatricians have adopted the practice of recommending vitamin D supplements to all their patients.

Wanda Gayle, a mother of color in Miami, Florida, USA found herself being lectured on vitamin D supplements by her older daughter's pediatrician while she was still pregnant with her second child. "According to my doctor, this should begin before the age of two months," Wanda recounts. "He recommended it before I even gave birth, when I took my eldest for a well child visit." Because she lives in a climate with abundant sunshine and the baby is light-skinned, Wanda has decided not to supplement her younger child. Instead, she ensures that the family gets some outdoor time every week.

Wanda's decision may have some researchers and pediatricians concerned since, in the absence of UVB exposure, an infant's level of vitamin D in the first weeks of life is directly related to the mother's levels during pregnancy, and African-American women tend to have much lower stores of vitamin D than Caucasian women (Nesby-O'Dell et al. 2002; Good Mojab 2004). Darker skin tone is a risk factor for vitamin D deficiency.

In one recent study, the results suggest that 10 times as many African-American women than white women are deficient in vitamin D, and have a lower mean concentration of vitamin D in their bodies (Nesby-O'Dell et al. 2002). Further, the authors found that nutritional supplementation according to current FDA guidelines did not greatly reduce the deficiency, suggesting that the current recommendations may not be sufficient for these mothers. That the increase of rickets has affected the African-American populations in proportionately greater numbers has breastfeeding advocates concerned that the risks of rickets and the recommendation of vitamin drops for breastfed babies could derail their efforts at raising the low rate of breastfeeding in this community (Barber & Purnell-O'Neal 2003).

These concerns are related to some of the known barriers to breast-feeding: the fallacious belief that formula is nutritionally equivalent to human milk; the misconception that breastfeeding is a hassle; the scarcity of social support for breastfeeding mothers; and the negative media reports declaring that human milk is deficient in vitamin D. Health professionals and lactation consultants are challenged to counsel all mothers on prevention of vitamin D deficiency without undermining the breast-feeding relationship. Breastfeeding is not yet widely accepted in the US as vital to public health nor are breastfeeding rates high. However, in Canada and Sweden, the rates of breastfeeding are high despite long-standing and widely practiced recommendations of vitamin D supplementation. In these northern countries, breastfeeding is the norm and vitamin drops for babies are considered a complement to the many nutritional benefits of human milk.

There are other issues regarding vitamin supplements of which mothers should be aware. Vitamin drops containing vitamin D may contain other vitamins that are not necessary for exclusively breastfed infants and ingredients such as glycerin, propylene glycol, sweeteners, and preservatives (Good Mojab 2003). Vitamin supplements for babies have not been studied to determine whether they could cause harmful alterations in the infant gut (Good Mojab 2003). Rather than interfere with the baby's developing digestive system, a better answer may be supplementing the breastfeeding mother.

How much vitamin D supplementation women need pre- and post-natally to maintain adequate levels for themselves and their babies is still under debate. The American College of Obstetricians and Gynecologists does not recommend a daily prenatal vitamin for all women but only for mothers at high nutritional risk or whose diet is questionable (Nesby-O'Dell 2002). The Institute of Medicine of the US National Academies recommends 200 IU per day as an acceptable level of vitamin D consumption for all women between the ages of 15 to 50. However, some researchers warn that this may not be enough to maintain healthy levels of vitamin D in healthy people and call for additional research into revising the current recommendations (Heaney 2003). It even has been suggested that as much as 10 times the currently accepted recommendation (up to 2,000 IU per day) may be necessary to maintain normal levels of vitamin D in mothers and their breastfed babies (Good Mojab 2003). This result is controversial because it exceeds what is currently accepted as necessary on a daily basis. Many vitamin D researchers are calling for a re-examination of vitamin D requirements, including during pregnancy and lactation (Good Mojab 2004).

What about the costs of the supplements? Families must pay the cost of vitamin drops, which may be beyond the reach of some low-income families. What if these families are at a high-risk for nutritional rickets but cannot afford to purchase the drops recommended by their doctor or clinic? Could this difficulty convince at-risk families to abandon breastfeeding and accept free formula when available from a government agency, such as in the US?

Supplementation is a complex issue. This has led many researchers to stress the importance of sunlight's role in maintaining healthy levels of vitamin D. There is growing evidence that the sun's rays in small amounts are beneficial and other diseases can be prevented by safe exposure to the sun. But what is considered safe? According to Cynthia Good Mojab, MS, IBCLC, RLC:

No research exists examining the relationship between the risk of skin cancer and a lifetime of minimal levels of sun exposure just sufficient for the endogenous production of adequate levels of vitamin D. Therefore, there currently is no evidence that such levels of sun exposure increase the lifetime risk of skin cancer.

Research shows that exclusively breastfed Caucasian infants six months of age and younger living in a latitude comparable to the Midwestern United States can make adequate vitamin D with exposure to sunlight for 30 minutes per week (diaper only) or two hours per week (fully clothed without a hat) (Specker et al. 1985).

Since the most significant risks of sun exposure are based on sunburn and prolonged exposure to UV rays, mothers should always be prepared with protective clothing and to keep their nursling out of the sun after a brief period of exposure (Shaikh & Alpert 2004). Since the needed duration of exposure is highly individual based on the family's geographic location, skin pigmentation, lifestyle, and other factors, an informed decision about whether or not to supplement with vitamin D drops can be aided by both consulting a health care provider and by learning more about sunlight deficiency. Breastfeeding mothers, professionals, and advocates should educate themselves with the facts on vitamin D, nutritional rickets, and safe levels of sunlight exposure.

In order to balance the AAP's recommendation with practices that encourage exclusive breastfeeding, in her recent editorial published in the Journal of Human Lactation, M. Jane Heinig, PhD, IBCLC, recommended that lactation consultants "remind and reassure families that breastfeeding is the optimal method of infant feeding" and "advocate for international research on safe UVB exposure levels for infants and children" (Heinig 2003).

Are you and your baby at risk for vitamin D deficiency?

Vitamin D is a steroid hormone-misclassified as a vitamin in 1922-that is produced in the body upon exposure of the skin to ultraviolet B (UVB) radiation in sunlight. Rickets is the bone-softening disease of childhood caused by inadequate exposure to UVB radiation. Risk factors for developing vitamin D deficiency and rickets include:

  • Low maternal levels of vitamin D
  • Indoor confinement during the day
  • Living at higher latitudes
  • Living in urban areas with tall buildings and pollution that block sunlight
  • Darker skin pigmentation
  • Use of sunscreen, seasonal variations in UVB radiation, and covering much or all of the body when outside

Exclusively breastfed healthy, full-term infants from birth to six months who have adequate exposure to sunlight are not at risk for developing vitamin D deficiency or rickets. Rickets occurs because of a deficiency in sunlight exposure, not because of a deficiency in human milk.

Adapted from the April 2003 LLLI media release, "Sunlight Deficiency, 'Vitamin D,' and Breastfeeding." More information is available online at


Barber, K. and Purnell-O'Neal, M. The politics of vitamin D: Questioning universal supplementation. Mothering 2003 Mar-Apr; 117:52-63.
Good Mojab, C. Personal communication, July 2, 2004.

Good Mojab, C. Sunlight deficiency: A review of the literature. Mothering 2003 Mar-Apr; 117:52-63.

Good Mojab, C. What ingredients are in vitamin supplements? Mothering 2003 Mar-Apr; 117:52-63.

Heaney, R.P. et al. Human serum 25-hydroxycholecalciferol response to extended oral dosing with cholecalciferol. Am J Clin Nutr 2003; 77(1):204-10.

Heinig, M.J. Vitamin D and the breastfed infant: Controversies and concerns. J Hum Lact 2003; 19(3).

Nesby-O'Dell, S. et al. Hypovitaminosis D prevalence and determinants among African American and white women of reproductive age. Am J Clin Nutr 2002 Jul; 76(1):3-4.

Shaikh, U. and Alpert, P. Practices of vitamin D recommendation in Las Vegas, Nevada. J Hum Lact 2004; 20(1).

Specker, B. et al. Sunshine exposure and serum 25-hydroxyvitamin D concentrations in exclusively breastfed infants. J Pediatr 1985; 107:372-76.

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