Vitamin D is a fat soluble vitamin critical for musculoskeletal health. It is sometimes known as the “sunshine vitamin” because it is produced in the skin in response to natural sunlight. Vitamin D is unique from other vitamins because of it’s hormone-like function in the body. 


While many are familiar with vitamin D for bone health, vitamin D is also well known for its impact on the immune system. 


First, let’s break down the different types of Vitamin D, and how they behave in the body. 


There are two types of vitamin D in the human body- storage vitamin D 25(OH)D and active vitamin D 1,25(OH)D. The body uses the active vitamin D to fight inflammation and infections, and will use up more of the active vitamin D in acute situations of infections as well. 


Vitamin D deficiency is often more common during the winter months, along with higher rates of cold and flu. One study from the University of Edinburgh found a connection between vitamin D and multiple sclerosis (MS). The researchers observed that vitamin D was able to activate T cells - which play a critical role in helping to fight infections. In people with autoimmune conditions such as MS, these T cells start to attack the body’s own tissues. (2) 


In another recent study, researchers found low levels of vitamin D concentration among children and infants with respiratory tract infections, while children exposed to sunlight seem to have fewer respiratory infections. Vitamin D is thought to have immunomodulatory effects on the immune system. (1) 


A recent randomized control study examining Japanese school children tested whether taking 1200 IU of vitamin D daily would impact winter flu rates. The study looked at 340 children for four months in the winter. The control group was given a placebo. They found that among the children given vitamin D daily, the influenza rates were 40% lower compared to the placebo group. (67)


Another meta-analysis indicated that vitamin D supplementation lowered risk of acute respiratory infections. (68) 


Vitamin D does not act alone. One thing to consider with vitamin D is to ensure there are adequate cofactors for vitamin D metabolism. 


Co-Factors of Vitamin D:

  1. Magnesium - often gets depleted quickly with infections and inflammation 
  2. Vitamin A
  3. Vitamin K2
  4. Calcium
  5. Zinc 
  6. Boron 


So, What Can You Do? 

Get your child’s vitamin D status checked at the GP and see if vitamin D supplementation is needed. Be sure to include plenty of foods that contain the vitamin D co-factors, and ensure your child is getting enough sunlight whilst still being protected from harmful UV rays. 


Vitamin D supplementation is especially important in the winter months with less exposure to sunlight. Unfortunately, getting sun exposure through a window does not have the same effect as direct sunlight, as window glass blocks UV rays. 


By: Anabelle Clebaner MS, RDN 





Brittany Darling
Tagged: Vitamin D