What does vitamin D do?
Vitamin D helps the body absorb calcium and phosphorus to build strong bones. It also has a role in preventing cancer and autoimmune diseases (conditions in which the body is tricked into thinking your cells are not your own so it attacks them).
Too little vitamin D can cause rickets, a softening and weakening of the bones. Signs of weakened bones are subtle, so damage may occur long before any problem is noticed. Weakened bones in infants and young children can result in bowed legs, soft skulls, and delays in crawling and walking. While rickets is still considered a rare disease, doctors in the US are seeing more and more infants and children with the disease.
New studies at Harvard University1 and in Canada2 also found that very sick hospitalized children often had too little vitamin D in their blood. While too little vitamin D cannot be blamed for making children sick, the studies suggest that if children don’t have enough vitamin D when they get sick, they are sicker and stay sick longer.
How do we get vitamin D?
Our bodies make vitamin D when direct sunshine hits our skin, especially around midday. But infants cannot get vitamin D from the sun if they are wearing sunscreen, if the sunlight comes through a window, or if it is early morning or late afternoon sun. Because early exposure to sunlight increases the risk of skin cancer, most doctors recommend keeping infants less than 6 months of age out of direct sunlight. Luckily, infants (children and adults, too) can also get vitamin D from a vitamin supplement. Vitamin D can be given to infants as part of their infant multivitamins (Poly-vi-sol or Vi-Daylin ADC, for example) or by itself.
What is the right dose?
For breastfed infants, the usual dose is 400 units. For partially breastfed infants or formula-fed infants who do not drink 1 liter of formula each day, the doctor may prescribe a much smaller dose. Too much vitamin D can cause nausea and vomiting, loss of appetite, abdominal pain, muscle weakness, joint pain, confusion, and fatigue. It can also lead to more serious problems such as kidney damage. So it’s important to give the exact amount of vitamin D prescribed by the infant’s doctor.
How do dosing errors happen?
Liquid vitamin D comes in different doses and strengths (Figure 1) ranging from 5,000 units per 5 drops to 400 units per drop to 400 units per 1 mL. The higher doses (5,000 units, 2,000 units, or 1,000 units) are intended for older children and adults; the lower doses (400 units) are for infants and young children. Mistakes can happen if parents accidentally purchase the concentrated, higher doses of the adult vitamin D liquid and give it to their infants.
This mistake happened just a few weeks ago. A mother unknowingly purchased the concentrated adult vitamin D supplement (2,000 units per drop) for her infant. The infant’s doctor had told the mother to give 1 mL of a vitamin D supplement to her child daily. The doctor did not tell the mother which brand of vitamin D drops to buy. He assumed she would purchase a commonly used Enfamil brand supplement, D-Vi Sol, which contains 400 units of vitamin D per 1 mL (Figure 2). The error was noticed several weeks later during a follow-up office visit after the infant’s mother showed the doctor the vitamin D supplement she was using. The infant had received at least 40,000 units of vitamin D per day because she gave the child a full dropper (about 1 mL) of the adult supplement! Fortunately, the infant was not harmed although the amount of vitamin D in her blood was very high.
Are there other ways that dosing errors happen?
Liquid vitamin D for infants comes in two strengths that can easily be confused: 400 units in a single drop and 400 units in a dropperful, which is about 1 mL (Figure 3). For example, Enfamil’s D-Vi-Sol comes with a dropper that measure’s a 1 mL dose of the vitamin supplement, equal to 400 units. Vitacost Baby D drops and Baby Ddrops both contain 400 units of vitamin D per drop, which is given with a dropper or right from the dropper bottle (Figure 4). The concentrated drops are particularly problematic if the parent confuses the word “drop” for dropperful. If a dropperful (1 mL) instead of 1 drop of these highly concentrated supplements is given, an infant would receive about 40 times more vitamin D than needed with each dose.
Follow these recommendations to be safe when giving infants vitamin D supplements:
• Verify the need for a vitamin D supplement. If your infant is breastfed, partially breastfed, or drinks less than a liter of formula each day, ask your infant’s doctor whether a vitamin D supplement is needed. Do not give your infant a vitamin D supplement without checking with the doctor first.
• Know the dose. If your infant’s doctor recommends a vitamin D supplement, be sure you understand the correct dose—how many units to give your infant.
• Use the less concentrated liquid vitamin D. For infants and young infants, errors are less likely if you purchase a vitamin D supplement that contains 400 units per mL, not 400 units per drop. Here’s why:
- It is difficult to place just a single drop from the bottle or dropper into an infant’s mouth. If an extra drop accidentally slips out with the more concentrated product (400 units per drop), the infant would get twice as much vitamin D than prescribed.
- Using the 400 units per mL supplement will allow parents to measure a smaller dose of the medicine if the infant’s doctor prescribes less than 400 units daily.
• Purchase the right product. Check that you have not accidentally purchased a supplement intended for older children or adults.
• Check the label. Always read the label of the vitamin D supplement carefully to determine how much liquid is needed to give your infant the correct dose of vitamin D. Remember, some supplements require just 1 drop for each 400 unit dose; others require 1 mL for each 400 units.
• Use the right dropper. Always use the dropper or measuring device that comes with the supplement to measure your infant’s dose. Ensure the dropper is marked so that the units of measure are clear and easy to understand. Also make sure that the units of measure correspond to those mentioned in the instructions. If you do not understand, ask your pharmacist to show you.
• Know how to measure doses. If you are not sure how to measure the correct dose of vitamin D, ask your pharmacist or other healthcare provider to show you using the product and the measuring device that came with it.
1) Madden K, Feldman HA, Smith EM, Gordon CM, et al. Vitamin D deficiency in critically ill children. Pediatrics. 2012; 130(3):421-8.
2) McNally JS, Menon K, Chakraborty P, Fisher L, et al. The association of vitamin D status with pediatric critical illness. Pediatrics. 2012; 130(3):429-36.