Children and Vitamin D
Health and Wellness
March 24, 2013
The study arose out of concerns that Canadian children between the ages of 1 and 8 years were not consuming enough vitamin D. Subjects were randomly selected from daycares through Montreal, and food intake, supplementation and sun exposure were assessed. Sunscreen use was prevalent among 79.4% in the summer and 3% in the winter. Preschoolers consumed a daily median of 2.4 servings of fluid milk and 3.8 servings of dairy products. Milk and fish were the major contributors to vitamin D intake, followed by composite meals and yogurt. The median vitamin D supplement dosage was 7.1 µg/d (284 IU).
Though concentrations for vitamin D were higher among preschoolers who consumed vitamin D, very few children (only 4.5%) had a concentration lower than 40 nmol/L. Also, vitamin D concentrations didn’t vary by ethnicity or BMI, even when controlled for age, sex and sunscreen use, and by milk or fish consumption, dairy, and supplement intake.
“At first I was slightly surprised by our findings but after a thorough examination of the results, several factors might have contributed to the good vitamin D status of this group. Even though sunscreen use was widely prevalent among this group, sunscreen might not be adequately applied in the general population thus, endogenous vitamin D synthesis might still occur. Also, children had a very good intake of calcium in this study, thus utilization of vitamin D for calcium homeostasis would be lessened,” says Dr. Jessy El Hayek, study co-author.
Another possible explanation for the robust vitamin D status in the study might relate to higher endogenous synthesis (vitamin D synthesis in the skin following sun exposure) capacity in young children compared with adults. Even with the use of sunscreen, ambient sunlight exposure made an important contribution to vitamin D status here, suggesting that EAR value may be too high for this age group. Researchers found the median vitamin D concentration to be 74.4 nmol/L. The Institute of Medicine (IOM) recommends vitamin D plasma concentrations to be above 30 nmol/L. Under 30 nmol/L is defined as deficiency.
“The recommendations for vitamin D intake were clearly set based on minimal sun exposure. Based on our study, the recommendations seem to overestimate dietary requirements of preschool children in the general population. Our data suggest that endogenous synthesis might account for a greater proportion of vitamin D than anticipated and that future recommendations may have to be positioned in the context of safe and typical amounts of sun exposure,” says El Hayek.
Future recommendations will have to weight the importance of sun exposure with the importance of sun protection. It is a delicate balance. The body needs vitamin D to absorb calcium, and without enough of it, the body can’t absorb calcium efficiently from the diet, and instead takes calcium from the bones, which weakens them. Children attending daycares in Montreal are regulated in terms of strict governmental guidelines regarding the amount of time spent outside daily. Sun safe practices are encouraged and followed, particularly during the warmest summer months.
A huge debate exists regarding safe sun exposure practices and synthesis of vitamin D. Some scientists suggest 5 to 10 minutes of unprotected UV exposure to allow some vitamin D synthesis followed by the application of sunscreen. On the other hand, most dermatologists have argued strongly that all unprotected sun exposure contributes to cumulative skin damage.
“Foods that are rich in vitamin D such as milk, yogurt and fatty fish are nutrient dense foods that could provide calcium, phosphorus, protein and essential fatty acids, which are all important for healthy growth and development of bones in preschool children. Accordingly, all these foods should be encouraged as part of a healthy diet for children. Further within the whole debate regarding sun exposure and risk of cancer, diet remains a safe non-carcinogenic alternative,” says El Hayek.
The IOM recommends no more than 4,000 IU per day of vitamin D for adults, and between 2,500 and 3,000 for kids in the age 1 to 8 years bracket. A diet adequate in vitamin D is still considered the safest approach to obtaining the necessary vitamin D.