Vitamin D | The Outdoor Vitamin

Vitamin D | The Outdoor Vitamin


Vitamin D is in fact a hormone with many a function in the maintenance of human health. It is
possibly most commonly known for its role in bone health as it is required for the absorption of
calcium but this is not the only reason we need vitamin D. This hormone is also involved in the
immune system.
The immune system itself is a very complex arrangement of cells and proteins involved in the
defence against infection. Vitamin D deficiency has been linked to and increased risk for infections
and autoimmune diseases which are on the rise. This makes sense given the important role that
vitamin D plays in the immune system. With a lack thereof, how can the immune system function
optimally?
Due to South Africa’s typically sunny climate, it is not regulation for foods to be fortified with vitamin
D. There are however and increasing number of foods with added vitamin D available in
supermarkets. Vitamin D is not found in large amounts in a diet of whole plant foods, lean proteins,
dairy products and plant fats and therefore achieving an adequate intake even through a healthy
diet is not possible in South Africa. Interestingly, mushrooms can make their own vitamin D in the
same way that humans do. This is however provided that they grow in the sun which is not usually
the case for this fungi family.
The best way to ensure optimal vitamin D status is through regular sun exposure. When exposed to
sunshine, the skin produces vitamin D3. Any vitamin D received from plant foods is in the form of
vitamin D2. The liver and kidneys convert both vitamin D3 and D2 into the storage form of D25,
which the body cells then convert into the active hormone D1.25, also known as calcitriol. When
testing blood levels of vitamin D, D1.25 is measured to determine vitamin D status.
As we learn more about vitamin D and its relationship to immune health, studies have revealed that
D1.25 together with vitamin D receptors are responsible for initiating many different genes that are
significant in the immune systems. Improvement in vitamin D status will have a positive impact on
the possible negative outcomes of deficiency such as autoimmune diseases and cancers which have
been linked to low vitamin D levels. The good news is that a deficiency in vitamin D is easy to test for
and easy to treat. Under the care of a doctor, vitamin D supplementation is cost effective.
During the school day, there are up to three opportunities for children to be outdoors and get
sunshine on their faces and arms, first break, second break and sporting activities. Children
attending aftercare may also spend more time playing outside after school with their peers. When it
comes to weekends and school holidays, many children favour screen time over outdoor play and
this reduced sun exposure can have negative long term consequences on bone health and the
immune system.
While we are and should be cautious with excessive sun exposure due to the risk of skin cancer, the
use of sunscreen unfortunately blocks the synthesis of vitamin D. Daily sun exposure without
sunscreen for short durations of 15 - 20 minutes is sufficient to build up vitamin D stores. During
school holidays and on weekends this may require purposeful intent if screen time is the preferred
source of entertainment.

Ways to encourage vitamin D synthesis outside of school days:
 A game of hop scotch
 A skipping rope
 Family gardening
 Chores such as raking leaves or sweeping the drive way
 Playing Frisbee
 A basketball hoop
 A swing set
 A walk around the block
 A picnic lunch
 Playing fetch with the dog

As a bonus, these activities also count towards physical activity for the day and ultimately reduce
sitting time which is important in the prevention of obesity.