An increasing weight of research suggests that North Americans are not getting enough vitamin D. While the vitamin is present in some natural and fortified food sources, the human body gets most of its vitamin D from sunlight.
Overexposure to UV radiation is known to increase a child’s lifetime risk of developing skin cancer. How much vitamin D do children need, and is the widespread use of high SPF sunscreens contributing to a population-wide deficiency in the ‘sunshine vitamin’?
What is Vitamin D?
Vitamin D is a fat-soluble vitamin that the body synthesizes when exposed to UVB rays from the sun. It is also present in some foods. Foods naturally containing vitamin D include tuna, salmon, mackerel, beef liver, cheese and egg yolks. Other foods can be fortified with vitamin D – the most common being milk products, soy drinks, prepared cereals, infant formula, calcium-fortified fruit juices and yogurt. The vitamin can also be ingested in the form of supplements or liquid drops.
As soon as the skin is exposed to the sun’s energy, a chemical process begins that synthesizes UVB rays into vitamin D. Exposure to sunlight is a body’s natural and efficient way to produce and store as much of the vitamin as it needs.
In children, vitamin D works with calcium and phosphorous to build strong bones. In adulthood, sufficient intake of vitamin D has been linked to better bone health, prevention of osteoporosis, reduced risk of cardiovascular disease and lower incidences of some forms of cancer.
Vitamin D Deficiency
In a dietary supplement fact sheet for health professionals, the National Institutes of Health (NIH) indicate that the sun’s energy above 42 degrees north latitude is too low to promote adequate vitamin D synthesis in the body between the months of November and February. On a map, this latitude can be traced by an imaginary line starting at the northern border of California and running across the U.S. to Boston, Massachusetts. The further north a population lives, the fewer months of UV exposure it has to naturally synthesize vitamin D from sunlight.
According to the NIH, people living below 34 degrees north latitude are generally exposed to enough UV radiation to enable their bodies to produce adequate vitamin D year round. However, vitamin D deficiency can still exist in sun-drenched populations.
Severe vitamin D deficiency in children can lead to a bone disease called rickets. The prevalence of this condition in the U.S. was dramatically reduced with the introduction of foods fortified with the vitamin.
Scientific research published in the Archives of Internal Medicine (AIM) in 2009 suggest that a vitamin D serum 25(OH)D level of 30 ng/mL in the body is the minimum necessary for general health, although this has not been proven. Based on this benchmark, the study’s researchers suggested that only 23% of adolescents and adult Americans are getting enough Vitamin D. The AIM report concludes that current Recommended Daily Intakes (RDI) of vitamin D, particularly for those living in northern latitudes, are too low.
Recommended Daily Intakes of Vitamin D for Children
In a news release published in October 2009, the American Academy of Pediatrics (AAP) cited a study that found that millions of infants and children in the U.S. have lower-than-recommended levels of vitamin D. The Academy stated “The AAP recommends that children should have vitamin D levels of at least 50 nmol/L (20 ng/ml) and the authors found over 6 million children below this level.” The RDI of vitamin D recommended for infants and children by the AAP is 400 international units (IUs).
On March 22, 2010, the AAP issued a statement recommending that pediatricians encourage parents to give vitamin D supplements to breastfeeding infants and those receiving less than 33.8 ounces (slightly less than one quart, or one litre) of infant formula daily.
Vitamin D and Sunscreen Use
The AIM study sought to expose trends in vitamin D synthesis by comparing data collected for the period from 2001 to 2004 against that from 1998 to 1994. In surveying the data, authors noticed a decline in vitamin D serum levels over time.
The authors suggested that declining sun exposure resulting from increased time spent indoors, combined with widespread use of sunscreens with sun protection factors of SPF 15 and higher, could explain the rise in vitamin D deficiency. They write “Although widespread campaigns for sunscreen use and sun avoidance…have reduced the incidence of skin cancers, sunscreen with a sun protection factor of 15 also decreases the synthesis of vitamin D3 by 99%.”
Has Sun Protection Gone Too Far?
Some suggest that short bursts of sun exposure without sunscreen enable the body to produce more vitamin D. For example, a widely-publicized University of Manchester study published in 2005 suggested that brief exposure to the sun before applying sunblock could promote more production of vitamin D.
While this makes sense in theory, neither the NIH nor the AAP recommend that parents discontinue using sunscreens on children. Overexposure to UV radiation in childhood can have lifetime consequences – the most serious being an increased risk of skin cancer. To date, there is no consensus on a safe level of sun exposure that will promote synthesis of vitamin D while protecting children from long-term skin damage.
Most pediatricians, cancer groups and scientists agree that the benefits of using sunscreen far outweigh the risks. Even a few minutes of UV exposure can burn a child's delicate skin.
Resources for Parents
The website Healthy Children provides recommendations for ensuring children get enough vitamin D and also lists natural food sources of the so-called "sunshine vitamin."
The NIH reports that America’s Food and Nutrition Board (FNB) set up an expert committee in 2008 to review current RDIs for vitamin D and is expected to release a report on new RDIs for the vitamin in May 2010.
A number of helpful articles on the use of sunscreens and sunblocks for children can be found online.
Anne Williams - Anne is a freelance writer and communications consultant based in Vancouver, Canada.
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