Low blood vitamin D levels may be associated with an increased risk of common colds

January 9, 2012

According to a new US study, children who are deficient in vitamin D could halve the number of upper respiratory infections they contract by taking supplements.

In the study, the serum vitamin D concentrations and cases of common colds were analyzed for 247 third- and fourth-graders who drank a daily dose of milk fortified with 300 international units ( IU) of vitamin D or normal milk without additional vitamin D for three months (1). The study results showed that at the beginning of the study, the children had an average vitamin D level of about 7 nanograms per milliliter (ng/ml). Any level below 20 ng/ml is considered a deficiency. At the end of the trial, blood levels of vitamin D in the control group remained the same, while levels in the group who took supplements rose to an average of
19 ng/ml. In addition, the children who took vitamin D supplements had 50% fewer colds.

The researchers commented that they had selected the study participants from the city of Ulaanbaatar in Mongolia, lying at about the same latitude as Maine and Washington in the United States, because the combination of an extremely cold climate and the high latitude restricts the amount of time children play outside in the sun. Government studies (NHANES) have shown that about 20% of US children under the age of 12 have a vitamin D deficiency, rising to 50% in African American children. The researchers worry that we might soon see more and more incidences of vitamin D deficiency, because kids spend a lot of time indoors playing video games and enjoying other indoor pastimes.


  1. Camargo C. A. et al. Randomized Trial of Vitamin D Supplementation and Risk of Acute Respiratory Tract Infection in Mongolia. Pediatrics. Published online August 2012.