Vitamin D Deficiency in Infants and Children

By Steven Rothrock, MD, FACEP, FAAP on September 23, 2011

Recently, the news media has been raising alarms about vitamin D deficiency in the United States, Canada and Europe.  Should parents be worried that their infant or child is deficient in this nutrient?

Where Does Vitamin D come from?

Vitamin D is a fat-soluble vitamin which means it is stored in body fats and stays in the body for a long time. The primary food sources of vitamin D are milk, dairy products, egg yolks, beef liver, certain mushrooms (Shitake) and oily fish (tuna, sardines, mackerel, herring, salmon).  In the US, a lot of foods are fortified with vitamin D during their production including milk, soy beverages, yogurt, margarine, orange juice and breakfast cereals.1 Our skin contains an inactive form of this vitamin which is converted to active vitamin D after exposure to ultraviolet (UV) radiation from the sun.  This internal process involves conversion in the liver and kidneys to produce the active form of vitamin D. Vitamin D aids in the absorption of calcium across the bowel wall and into the blood stream.

Why do we Need Vitamin D?

Vitamin D promotes bone health with deficiencies causing osteomalacia or bone softening in adults and in extreme cases a brittle bone disease called rickets in children.  The best measure of vitamin D deficiency is a serum 25-Hydroxyvitamin D [25(OH)D] level.1 Readers should be aware that different experts define deficiency (low levels) and insufficiency (normal levels but less than optimal) using different numbers.  The Table below uses definitions from the National Institutes of Health (NIH).1

Healthy & Unhealthy Vitamin D [(25(OH)D] Levels1

 

 

 

Levels

Blood level

nanomoles

per Liter

(nmol/L)

Blood level

nanograms per

milliliter

(ng/ml)

Health State Associated with

Different Vitamin D Levels

Low & Very low = Deficiency

 Very low

< 30

< 12

Rickets in children, Osteomalacia in adults

 Low

30-50

12-20

Poor bone health

 Normal

> 50-125

> 20-50

Adequate levels (some experts state that 50-75 nmol/L or 20-30 ng/m  is consistent with vitamin D insufficiency)

 High

> 125 (or 150)

> 50 (or 60)

Side effects from too high levels

Who is at Risk for vitamin D deficiency?

Overall 9-24% of children and adolescents are deficient in vitamin D. Forty to 61% have insufficient vitamin D which means their levels are in the normal range but less than optimal.2-4

For the first two months of life, infants use vitamin D stores they obtained from their mother.5  If their mother was deficient in vitamin D, they are at risk for deficiency of this vitamin.  After 2 months, all vitamin D is either produced in their skin or ingested in their diet. Since breast milk contains little vitamin D, infants who are purely breastfed are usually deficient in vitamin D.5  Infant formulas, on the other hand, are required to be fortified with vitamin D in the United States and Canada.1,5,6 They are not required to be fortified in the United Kingdom, Australia, New Zealand and much of Europe although fortified infant formulas are available in these countries.6 Breast feeding with vitamin D supplementation is still preferred in infants because it lowers the risk of diabetes, certain cancers, asthma, appendicitis, obesity, many infections, and improves test scores and brain development compared to formula feeding.7

Beyond infancy, risk factors for vitamin D deficiency include darker skin (non-white skin has less effective sun conversion), living in higher latitudes and cloudy areas (less sun), air pollution (blocks UV rays from sun), sickle cell anemia, diabetes, chronic kidney disease, gastrointestinal diseases that inhibit absorption of vitamin D and taking certain medicines (e.g. steroids, some seizure medicines).8-12  Children and adolescents are at higher risk for vitamin D deficiency if they drink less milk or spend over 4 hours per day watching TV, playing video games or using computers.  Vitamin D deficiency is also associated with ingestion of soft drinks and juices, excess body fat, poor cardiovascular fitness, higher blood pressure and lower HDL cholesterol - the good cholesterol.2,8,9

Adolescents have lower vitamin D levels compared to younger children and infants. Up to 24% of teenagers are vitamin D deficient.4,13 A teenager’s risk of vitamin D deficiency increases if they drink soft drinks, fruit juice or iced tea and decreases if they drink milk, eat cold cereals or take vitamin supplements.4 Girls may have a higher risk than boys, in part, because they eat less foods with vitamin D and they exercise less.4,14 Like other age groups, excess weight, less exercise and living in more northern latitudes increases the risk of vitamin D deficiency.4

Why are Low Vitamin D Levels Bad?

In addition to promoting bone health, vitamin D aids cell growth, nerve and muscle function, promotes a strong immune system and reduces certain types of inflammation. Infants and children with low levels have a higher risk of developing bronchiolitis, RSV (respiratory syncytial virus) infections, croup, diabetes, wheezing, pneumonia, throat and ear infections.1,3, 12,15,16 Adolescents with low vitamin D levels have a higher blood pressure, higher blood sugar and diabetes risk, lower HDL cholesterol and higher triglyceride levels increasing their risk for heart disease later in life.17

In adults, vitamin D deficiency is associated with a higher risk of heart attacks, hip fractures, certain infections like tuberculosis and pneumonia, multiple sclerosis, rheumatoid arthritis, high blood pressure, and insulin resistance with a higher risk of developing diabetes.3,12,16,18  The risk of developing and dying from colorectal, prostate, breast, pancreatic, esophageal cancer, leukemia and lymphoma is also increased.12,18

Recommended Vitamin D Intake

The amount of Vitamin D needed is 400 IU (International Units) per day for infants 12 months old and younger, with children aged 1 year old and older requiring 600 IU per day.14,19  All breastfed infants including those who are partially breastfed require supplementation with 400 IU per day after breast feeding has been well established and definitely by the time they are 2 months old. Supplements need to be continued until infants are weaned to at least 1 Liter/day or 1 quart/day of vitamin D fortified formula or whole milk.  Whole cow’s milk should not be used until infants are more than 12 months old. Reduced fat cow’s milk is appropriate for overweight infants beyond this age. Infants > 12 months old and children who are not ingesting at least 1 Liter per day of vitamin D formula or milk require supplementation with 600 IU/day of vitamin D.14 Adolescents who do not ingest 600 IU of vitamin D per day also require supplementation.14

Infant vitamin D supplements are available at most drug stores including Baby Ddrops, Bio-D-Mulsion, D-Vi-Sol, Just D and NSI Baby-D’s.  Many infant and children multi-vitamin products contain vitamins A, D, C and sometimes B vitamins (e.g. Poly-Vi-Sol, Tri-Vi-Sol). Parents must be careful to read the container’s dosing recommendation and concentration before administering these products.  The FDA has issued a warning that confusing labels for infant vitamin D liquids can lead to an overdose of these products.20 For instance, 1 drop of Bio-D-Mulsion or Baby Ddrops or NSI Baby-D’s contains the recommended 400 IU dose for infants under 1 year old while Bio-D-Mulsion D Forte contains 2000 IU per drop - an amount well above the maximum tolerable upper level of vitamin D ingestion for infants.  Other products contain 400 IU or more vitamin D within each milliliter of liquid.  To ensure you are giving the proper amount, verify the product and dose with your doctor or pharmacist.  Have a second person independently read the vitamin D container or bottle to ensure that your infant or child is receiving the proper dose (400 IU). Make sure that you always keep the bottle of vitamin D in its original packaging and always use the dropper that comes with it. Only use products that have clear and easy to understand units of measurement marked on the dropper.

Infant formulas in the United States and Canada are required to be fortified with at least 40 IU per 100 kilocalories (1 ounce usually contains 20 kcal).  Healthy infants who are exclusively formula fed do not require supplemental vitamin D.  Supplements may be required for infants with certain underlying diseases that place them at risk for low vitamin D levels.

Vitamin D and the Sun

Throughout history, the main source of vitamin D in humans has been the sun and exposure to UVB light.  In light skinned adults, full body exposure to the sun during the summer for 15 minutes per day produces up to 20,000 IU of vitamin D.  However, a 10 fold higher exposure is needed for those who are dark skinned.19, 21 Other factors like latitude, season, cloud cover, air pollution, sunscreen use and the amount of skin covered with clothes also affects the amount of vitamin D produced.19,22 Exposure to sun light at young ages increases the lifetime risk of skin cancer.  The American Academy of Pediatrics recommends avoiding direct sunlight exposure in all infants < 6 months old and limiting sun exposure and promoting the use of protective clothing and sunscreens beyond that age.19,21,22 The American Academy of Dermatology states “Vitamin D should not be obtained from unprotected exposure to ultraviolet (UV) radiation”.  For these reasons, supplementation and diet are recommended over sun exposure for obtaining vitamin D.23

Can you get too much Vitamin D?

While vitamin D deficiency is harmful, excess or high levels can cause damage to blood vessels, kidneys and heart with formation of kidney stones, weakness, increased urination, and heart arrhythmias.  Certain cancers may also be more common with toxic or excessively high levels of vitamin D.  For this reason, the American Academy of Pediatrics has defined the maximum tolerable upper intake levels for vitamin D with toxicity developing at much higher levels than these cutoffs.  Healthy children given the recommended supplement of vitamin D (400 or 600 IU per day) are not at risk for vitamin D toxicity.14

Age

Recommended Daily Allowance

Excess Daily Vitamin D Intake

0-6 months

400 IU

> 1000 IU

7-12 months

400 IU

> 1500 IU

1-3 years

600 IU

> 2500 IU

4-8 years

600 IU

> 3000 IU

> 8 years

600 IU

> 4000 IU

Resources

U.S. Department of Agriculture list of foods containing vitamin D

Dietary reference intakes for calcium and vitamin D. Institute of Medicine of the National Academies.

American Academy of Pediatrics. Children’s Health Topics: Vitamin D.

Fat-Soluble vitamins and micronutrients: Vitamin D. National Report on Biochemical indicators of Diet and Nutrition in the US Population. Centers for Disease Control and Prevention.

Food and Drug Administration. Infant overdose risk with liquid vitamin D.

The takeaway message

Vitamin D deficiency is common in the US.  Some experts would say it is an epidemic among our children and adolescents.  Vitamin D deficiency causes and contributes to a large number of health problems.  Parents need to be aware of risk factors for this problem and how to get the right amount of vitamin D. Like a lot of things in medicine, a proper diet (esp. milk if > 1 year old), staying away from bad foods and beverages (esp. soft drinks), weight maintenance and exercise will go a long way toward keeping your child healthy and preventing disease.



References

  1. Dietary Supplement Fact Sheet: Vitamin D. Office of Dietary Supplements. National Institutes of Health.
  2. Kumar J, Muntner P, Kaskel FJ, et al. Prevalence and associations of 25-Hydroxyvitamin D deficiency in US children: NHANES 2001-2004. Pediatrics 2009; 124: e362e370.
  3. Mansbach JM, Ginde AA, Carmargo CA. Serum 25-hydroxyvitamin D levels among US children aged 1 to 11 years: do children need more vitamin D? Pediatircs 2009; 124: 1404-1410.
  4. Gordon CM. Prevalence of vitamin D deficiency among healthy adolescents. Arch Pediatr Adolesc Med 2004; 158: 531-537.
  5. Misra M, Pacaud D, Petryk A, et al. Vitamin D deficiency in children and its management: review of current knowledge and recommendations. Pediatrics 2008; 122: 398-417.
  6. Ministry of Health Australia. Nutrient Reference Values. Vitamin D.
  7. American Academy of Pediatrics. Breastfeeding and the use of human milk. Pediatrics 2005; 115: 496-506.
  8. Dong Y, Pollock N, Stallmann-Jorgensen IS, et al. Low 25-Hydroxyvitamin D levels in adolescents: race, season, adiposity, physical activity, and fitness. Pediatrics 2010; 125: 1104-1111.
  9. Rovner AJ, O’Brien KO. Hypovitaminosis D among healthy children in the United States: a review of the current evidence. Arch Pediatr Adolesc 2008; 162: 513-519.
  10. Rovner AJ, Stallings VA, Kawchak DA, et al. High risk of vitamin D deficiency in children with sickle cell disease. J Am Diet Assoc 2008; 108: 1512-1516.
  11. Janner M. High prevalence of vitamin D deficiency in children and adolescents with type 1 diabetes. Swiss Med Wkly 2010; 140: w13091.
  12. Holick MF. Vitamin D deficiency. New Engl J Med 2007; 357: 266-281.
  13. Yarley EA. Assessing the vitamin D status of the US population. Am J Clin Nutr 2008; 88: 558S-564S.
  14. Abrams SA. Dietary Guidelines for calcium and vitamin D: a new era. Pediatrics 2011; 127: 566-568.
  15. Chesney RW. Vitamin D and the magic mountain: the anti-infectious role of the vitamin. J Pediatr 2010; 156: 698-703.
  16. Mansbach JM, Carmargo CA. Bronchiolitis: lingering questions about its definition and the potential role of vitamin D. Pediatrics 2008; 122: 177-179.
  17. Reis JP, von Muhlen D, Miller ER, et al. Vitamin D status and cardiometabolic risk factors in the United States adolescent population. Pediatrics 2009; 124: e371.
  18. Holick MF. Vitamin D: extraskeletal health. Endocrinol Metab Clin North Am 2010; 39: 381-400.
  19. Wagner CL, Greer FR. Prevention of rickets and vitamin D deficiency in infants, children and adolescents. Pediatrics 2008; 122; 1142-1152.
  20. US Food and Drug Administration. Infant overdose risk with liquid vitamin D.
  21. Balk SJ, Council on Environmental Health and Section on Dermatology. Ultraviolet radiation: a hazard to children and adolescents. Pediatrics 2011; 127: e791-817.
  22. Perrine CG, Sharma AJ, Jefferds MED, et al. Adherence to vitamin D recommendations among US infants. Pediatrics 2010; 125: 627-632.
  23. American Academy of Dermatology. Position Statement on Vitamin D.