Vitamin D and RDA for Children

Vitamin DIt’s probably of little surprise that we take issue with some of the Recommended Daily Allowance values and how they’re often determined. Case in point: New research published in the Journal of Clinical Endocrinology and Metabolism suggests that the current children’s RDA for Vitamin D (200 IUs) does not sufficiently support the “bone growth and musculoskeletal health of children and adolescents.”

The RDA value for children was set at 200 IUs because, unlike testing for adults’ dosage, there wasn’t adequate research into the benefits of higher amounts.

Vitamin D deficiency is a growing problem around the world, including in developed countries where children spend little time outside. Questions have existed for some time regarding the adequacy of the current RDA, particularly for older children and adolescents, who undergo a great deal of bone growth. As the researchers of this study note, Vitamin D levels during adolescence have bearing on a child’s future bone density and risk for other diseases.

For this placebo-controlled study, researchers gave children various doses of vitamin D at various intervals and measured the impact this had on serum levels of 25-OHD. For the short-term study, 25 students (15 boys and 10 girls) received one-weekly, 14,000 IU doses of vitamin D for eight weeks. Serum levels of 25-OHD were then measured for an additional eight weeks. This portion of the test was conducted during the summer and early fall, when the highest natural levels of vitamin D are reached. For the long-term, one-year study, 340 students (172 boys and 168 girls) received either a low dose of vitamin D (1,400 IUs each week) or a high dose (14,000 IUs each week).

The study notes that previous research has indicated no difference between daily and weekly supplementation of Vitamin D. To ensure full compliance, the researchers required weekly, on-site administration of the supplement.

At the end of the study periods, only those children who had received the “high” dosage of vitamin D had the recommended optimum serum (blood) levels as they are defined for adults. (There is less agreement about an ideal serum level for children.) Other benefits were seen in those who received the higher dose. Researchers observed “substantial increments in lean mass, bone area and bone mass” particularly in girls. Their observations from the study caused them to suggest that serum OHD-25 (vitamin D) levels in the mid-thirties (ng/ml) may be a reasonable and beneficial target for this age group. The researchers noted that adolescents would be less likely candidates for toxicity because of their body’s use of the vitamin for constant growth.

And vitamin D is essential for every last one of us. As the researchers note, “Low vitamin D levels are associated with an increased risk of certain cancers (breast and prostate), autoimmune disorders and cardiovascular diseases.” Other risks? Depression. Osteoporosis. Cognitive impairment. Gait imbalance. Older men and women, in particular, are at risk for low levels or deficiency because of less time commonly spent outside and a decrease in the skin’s ability to “process” the nutrient from natural sun exposure.

Our recommendation for seedlings (and everyone else!)… As always, eat a healthy diet, supplement wisely, and get primal by spending adequate time outdoors.

We’d love to hear your thoughts and questions.

Leo Reynolds Flickr Photo (CC)

Further Reading:

Seedlings and the “Need” for Nature

Not Enough B-6?

Let the Sun Shine In

Raise Healthy Seedlings


Eating Fabulous: Vitamin D in Brain Function, Supplementation May Be Necessary

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