Vitamin Sunshine
An astonishing forty percent of healthy babies and toddlers in a recent study had low levels of vitamin D. Results of this important study appear in the June 2008 Archives of Pediatrics and Adolescent Medicine. Children can get vitamin D in the diet, but the skin can also make vitamin D in response to time in the sun. Optimal levels of vitamin D are important not only for bone health, but also for helping to prevent cancer, infections, and other important diseases. Severe vitamin D deficiency can cause rickets, a bone condition that has been increasing around the world (even in sunny California, Nevada, Texas, and North Carolina, among other US states).
What predicts low levels of vitamin D? The child’s gender? Their nutrition? The amount of time spent in the sun? The season of the year? Sunscreen use? The darkness of the skin? Parents’ health habits? The current study looked at healthy children up to age two who went to Children’s Hospital Boston for a routine health visit over the course of a year and a half. Vitamin D levels were measured by blood tests. The 40 percent found to have low levels is similar to what a previous study found in US teens (42 percent not getting enough). About 12 percent of the healthy babies and toddlers in this study had levels low enough to be called vitamin D deficient. Their bones were checked by x-ray, and about a third of them already had decreased bone density. And 7.5 percent of them already had the bone changes of rickets.
Overall, the season of the year didn’t correlate with the children’s odds of vitamin D deficiency (although, unexpectedly, average vitamin D levels in the babies were higher in the winter!). There was no affect on vitamin D levels found based on the amount of time spent outdoors, skin color, sun sensitivity, or sunscreen use – considered individually or together. Nor was there any difference based on gender. Breastfed babies, though, who weren’t getting vitamin D drops, were 10 times more likely to be deficient.
Among toddlers, vitamin D levels closely mirrored how much milk they drank. Eating fortified cereal had no impact on vitamin D levels. In toddlers, vitamin D did vary a bit with body weight. Obese toddlers were somewhat more likely to have lower vitamin D levels.
Bottom line: I support the American Academy of Pediatrics recommendation that breastfed babies all start taking at least 200 IU of vitamin D within the first two months of life. I think 400 IU may even prove to be better. It’s not that breast milk is lacking; it’s that throughout most of human history babies spent a lot more time outdoors than they do today, without sunscreen, and with bodies adapted to the latitude where they lived. In this Boston study, the child who was outside the most averaged only 3 hours outdoors per day. When my parents were young, a lot of children lived on farms and were outside most of the day during the summer months. Because of the changes in the earth’s ozone layer, though, it’s no longer safe to spend so much time in the sun without sunscreen, which puts the brakes on making vitamin D. Some sunshine is great for kids, but in this century it’s important to protect kids from too much sun exposure. –What about older kids? For children age one through eight who don’t drink 2 cups of vitamin D milk a day, or for those over nine years old who don’t drink 3 cups of vitamin D milk a day, I recommend ensuring another source of vitamin D.
Alan Greene, MD, FAAP
Gordon CM, Feldman HA, Sinclair L, Williams AL, Kleinman PK, Perez-Rossello J, Cox JE. Prevalence of Vitamin D Deficiency among Healthy Infants and Toddlers. Archives of Pediatrics and Adolescent Medicine. 2008; 162:505-512.
| July 8th, 2008 at 4:42 pm
Where would one find data to substantiate this claim about UV exposure?
“When my parents were young, a lot of children lived on farms and were outside most of the day during the summer months. Because of the changes in the earth’s ozone layer, though, it’s no longer safe to spend so much time in the sun without sunscreen, which puts the brakes on making vitamin D.”
| July 9th, 2008 at 1:38 pm
To go into this area more in depth, Paul, seems to me that there are three things to consider 1) was the ozone layer disrupted in the twenthieth century, resulting in more UV radiation 2) is radiation linked to skin cancer, and 3) is skin cancer really increasing?
One good place to look for data on this issue is Cancer Research UK. Their SunSmart program has pulled together a lot of the relevant research as well as practical tips: http://info.cancerresearchuk.org/healthyliving/sunsmart/
Men and women born in 1970 - now in their mid-30s – already are being diagnosed with malignant melanoma, the deadliest form of skin cancer. Shockingly, these young adults are being diagnosed with melanoma at the same rate as the elderly who were born in 1930 and who didn’t start developing melanoma until their 50s, according to a March 2005 warning by Cancer Research UK.
Melanoma risk throughout life is directly linked to excess sun exposure during childhood. A childhood sunburn can double the risk of melanoma later in life.
The ozone layer of the atmosphere absorbs 95 to 99 percent of the sun’s ultraviolet radiation before it strikes the surface of the earth. But NASA estimated in 2005 that the ozone layer was being reduced, on average, by 4 to 6 percent every ten years, largely from manmade chlorine products such as chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). Some years the ozone hole is bigger than others. 2006 was huge. 2007 is about average. Data isn’t in yet on 2008. Here’s a link to NASA’s ozone hole watch page, where they also have an educational module on the UV menace: http://ozonewatch.gsfc.nasa.gov/education/index.html
The US is on a schedule to completely phase out production and import of ozone-depleting substances by 2030 – but they will continue to affect the ozone layer for another century or more.
Because of changes in the ozone layer and changes in behavior, children born in the 70s got far more childhood ultraviolet exposure than those born in the 30s. Today’s children are at a higher risk still. They are three times more likely than their grandparents to ever develop malignant melanoma.
As to the shift from rural to urban living, May 23, 2007 was estimated to be the first day in all of history that more of the world’s population lived in or near cities than out in the country.
I don’t remember when in the 20th century this happened in the US, but at the begining of the century, farming and country life wre huge. By the close of the 20th century, only 21% of our population was rural, accorsing to the census bureau.
This is also complicated, of course, by the truth that sunshine, in moderation, is very good for us. Minimizing exposures during peak sun hours is one to to moderate exposures.
| July 17th, 2008 at 6:32 am
Thank you for this detailed explanation of an issue that I’ve been hearing/reading about for the last year. Have you seen the book “Green, Greener, Greenest: A Practical Guide to Making Eco-Smart Choices a Part of Your Life”? I now think about “healthy, healthier, healthiest” choices (walk to work wearing a hat, but leave my arms exposed so I can absorb some Vitamin D!)
| July 3rd, 2009 at 6:48 pm
Do you have a recommendation for a particular brand of infant vitamin drops for our 2-month-old? Our pediatrician recommends Tri-Vi-Sol A, C & D, but I am concerned about the preservatives in it: specifically polysorbate 80 and artificial colors and flavors. Are you aware of any better options? Also, are there any vitamin-D only drops?
Thanks!