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 www.lalecheleague.org/FAQ/vitamin.html.
|
References
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.
Last updated 11/17/06 by jlm.
Page last edited Sun Oct 14 09:29:48 UTC 2007.
