More people seem to be getting the message that too little vitamin D in our diets can lead to health problems. In addition to being at risk of developing rickets (extreme vitamin D deficiency), children with milder forms of vitamin D deficiency can develop weak bones and muscle weakness.
Why is vitamin D so important?
Vitamin D is a hormone that helps our bodies absorb both calcium and phosphorous, two very important minerals that help keep our bones strong.
Without enough vitamin D, we absorb 85-90% less of the calcium in our diet! And then, to keep calcium levels normal, our bodies pull more calcium out of our bones, causing osteopenia and osteoporosis.
Some experts also think that a low vitamin D level is associated with other conditions that are not linked to calcium and our bones, including some psychiatric conditions. The American Academy of Pediatrics even states that “new evidence suggests that vitamin D plays a vital role in maintaining innate immunity and has been implicated in the prevention of certain disease states including infection, autoimmune diseases (multiple sclerosis, rheumatoid arthritis), some forms of cancer (breast, ovarian, colorectal, prostate), and type 2 diabetes mellitus.”
The role of vitamin D in preventing infections, cancer, or anything else beyond preventing and treating vitamin D deficiency (extraskeletal effects) is far from proven though. In fact, a 2010 investigation by the Institute of Medicine (IOM) didn’t find any evidence to support a role for vitamin D in any other health conditions besides supporting bone health.
Surprisingly to many people, the IOM report also found that most people in North America are already getting enough calcium and vitamin D in their diet and that getting too much can be harmful. They also warned that “the number of people with vitamin D deficiency in North America may be overestimated because many laboratories appear to be using cut-points that are much higher than the committee suggests is appropriate.”
Tests for Vitamin D Deficiency
Although vitamin D testing seems to becoming part of the routine screening tests that some doctors order, it is important to keep in mind that only those at risk for having low levels should be routinely tested.
Are your kids at risk for vitamin D deficiency?
These high risk children can include:
- exclusively breastfed infants who don’t get a vitamin D supplement
- babies born to mothers with a vitamin D deficiency, especially premature babies
- children with chronic kidney or liver disease
- children with malabsorption syndromes (Crohn’s disease, inflammatory bowel disease, cystic fibrosis, etc.), as vitamin D is absorbed with fats in our diet
- obese children, because vitamin D is stored in fat tissue and is not readily available for use
- children with dark skin, who live at high latitudes, and/or spend a lot of time indoors (less vitamin D from sun exposure)
- children taking certain medications, including antiseizure medications and oral steroids
- children who simply don’t get enough vitamin D – at least 400-600 IU of vitamin D each day, depending on their age. This might include vegetarians, vegans, and children who simply don’t drink vitamin D fortified cow’s milk, soy milk, or almond milk, etc., or other foods that are high in vitamin D.
If your child falls into one or more of these risk factors for vitamin D deficiency, then talk to your pediatrician about testing his vitamin D levels.
Although different tests are available, the test that is recommended by the AAP and the Endocrine Society is the serum 25(OH)D level (25-hydroxyvitamin D). This actually measures the levels of a prehormone of vitamin D, calcifediol, but is thought to give a good idea of a person’s vitamin D status.
This vitamin D test is preferred over testing 1,25(OH)2D levels, another test that is available, as those levels can be normal or even elevated when someone has a vitamin D deficiency. Similarly, measuring vitamin D levels (the active hormone) has not been found to be helpful. Instead, we use 25(OH)D levels as a marker for vitamin D levels.
Treating Vitamin D Deficiency
Is your child’s vitamin D level low?
That question is a actually a little harder to answer than you might realize. According to the IOM, in discussing cut-points for 25(OH)D levels, or what’s low and what’s normal, “At this time, there is no central body that is responsible for establishing such values for clinical use.”
The serum 25(OH)D level is typically defined as low (vitamin D deficiency) in children if it is below 20 ng/ml. Some experts think that a 25(OH)D level above 16 ng/ml is normal for infants and children though.
Experts do agree that a level below 5 ng/ml is a sign of a severe vitamin D deficiency.
Recommendations for treating children with low vitamin D levels depend on their age, and might include:
- newborns: 1,000 IU /day vitamin D2 or D3
- children 1 to 12 months old: 2,000 IU /day vitamin D2 or D3
- children > 12 months old: 2,000 IU /day vitamin D2 or D3
These vitamin D supplements, together with adequate amounts of calcium, are usually continued for at least 1 to 3 months, at which time the child’s serum 25(OH)D level can be repeated to make sure it is responding to treatment.
“The upper limit for vitamin D is 1,000 to 1,500 IU/day for infants, 2,500 to 3,000 IU/day for children 1-8 years, and 4,000 IU/day for children 9 years and older, adults, and pregnant and lactating teens and women. Vitamin D toxicity almost always occurs from overuse of supplements.”
NIH Vitamin D Fact Sheet for Consumers
The Endocrine Society also advises that some children can take 50,000 IU of vitamin D2 once a week as an alternative treatment for vitamin D deficiency. Since you can definitely get too much vitamin D, be sure to talk to your pediatrician and make sure your child is getting the right dose before starting a treatment regimen for vitamin D deficiency.
Preventing Vitamin D Deficiency
Once you get your child’s vitamin D levels back into a normal range, it is important to take steps so that they don’t drop again.
To prevent vitamin D deficiency, the American Academy of Pediatrics recommends that healthy infants get at least 400 IU of vitamin D each day, while older children – toddlers to teens – get at least 600 IU. This vitamin D should come from some combination of:
- foods that are naturally rich in vitamin D – salmon, tuna, shitake mushrooms, etc.
- foods that are fortified with vitamin D – vitamin D fortified milk, orange juice, cheese, yogurt, margarine, and cereal, etc.
- a vitamin D supplement – with just vitamin D, vitamin D plus calcium, or a children’s multivitamin
What about sunlight? Can’t your kids just spend more time in the sun to boost their vitamin D levels?
Although we all have the ability to make vitamin D when we are out in the sun, it isn’t considered a good source of vitamin D. Intentional, unprotected (no sunscreen) exposure to the sun has risks of sunburn and skin cancer. And it is very hard to judge how much sun exposure is necessary to get adequate amounts of vitamin D. The intensity of the sun’s radiation varies greatly in different parts of the world and at different times of year and will also affect how much vitamin D your body makes.
Other Things To Know about Vitamin D Deficiency
- Raw milk, in addition to being unprocessed and unpasteurized, is unfortified and has very little vitamin D.
- Although other foods may be fortified with vitamin D, in the United States, only milk, margarine, infant formula, and “fortified-plant based beverages” are mandated by the FDA to be vitamin D fortified.
- In addition to low 25(OH)D levels, children with vitamin D deficiency will often have low phosphorous, high alkaline phosphatase, and high parathyroid hormone levels. These levels might be checked and monitored when kids are treated for vitamin D deficiency.
- Vitamin D2 (ergocalciferol, derived from plants) and vitamin D3 (cholecalciferol, derived from animals) are two major forms of vitamin D. Some experts think that vitamin D3 is more potent than vitamin D2, especially at higher doses. Still, these prohormones are converted to the same active form of vitamin D (calcitriol) in the liver and kidney.
- Some experts think that 25(OH)D levels between 21 and 30 ng/ml are a sign of vitamin D insufficiency in children, as in adults, and are a sign that the child needs more vitamin D in their diet.
- Although the use of sunscreen can block the synthesis of vitamin D by blocking UVB radiation and has been blamed for lower vitamin D levels in recent years, many people likely don’t use sunscreen properly and don’t use it consistently enough and so “sunscreen use may not actually diminish vitamin D synthesis in real world use.”
- Taking high doses of vitamin D is yet another nutrition fad which has been linked to serious consequences. Mega doses of vitamin D have been linked to kidney problems and tissue damage. That makes it important to stay below the upper limit that your child can likely take each day without causing harm, which ranges from 2,500 IU/day for toddlers to 4,000 IU/day for teenagers. Most only need 400 to 600 IU/day though.
Children with severe vitamin D deficiency are often managed by a pediatric endocrinologist or a pediatric nephrologist.
More Information on Treating Vitamin D Deficiency
- AAP – Vitamin D: On the Double
- The rise and inevitable fall of Vitamin D
- Help Your Child Build Healthy Bones
- NIH Vitamin D Fact Sheet for Consumers
- Study – American Academy of Pediatrics Clinical Report. Optimizing Bone Health in Children and Adolescents. Pediatrics. Pediatrics Oct 2014, 134 (4) e1229-e1243
- Study – Institute of Medicine Report. Dietary Reference Intakes for Calcium and Vitamin D. Released: November 30, 2010.
- Study – The Endocrine Society. Evaluation, Treatment, and Prevention of Vitamin D Deficiency: An Endocrine Society Clinical Practice Guideline. Journal of Clinical Endocrinology & Metabolism, July 2011, 96(7):1911–1930.
- Study – Misra, M. Vitamin D Deficiency in Children and Its Management. Pediatrics, Aug 2008; 122: 398 – 417.
Last Updated on January 17, 2017 by Vincent Iannelli, MD