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Hello. My name is Shir Azrielant from
the Zabludowicz Center for Autoimmune Diseases in Sheba Medical Center of Israel.
Today, I'm going to talk to you about "Vitamin D and Autoimmunity'.
Heliotherapy, meaning light therapy,
has been used since the ages of ancient Egypt, Greece,
and Rome, where sunlight was used to treat various medical conditions.
In the modern age,
Dr. Niels Ryberg Finsen was the first to use light radiation as treatment,
specifically in infectious skin diseases.
For which he was awarded the Nobel Prize in physiology and medicine in 1903.
In a study from 1983,
the immunological effects of solarium exposure were documented.
These and other studies have laid
the foundation for the modern researcher for the effect of
vitamin D on the immune system in general and on immunomodulation in particular.
The main source for vitamin D comes from
its biosynthesis in the skin in response to ultraviolet exposure.
In regards to dietary sources,
very few foods naturally contain
vitamin D. Fatty fish are relatively rich in the vitamin,
and small amounts of it can be found in shiitake mushroom and egg yolks.
Several foods are fortified with vitamin D,
including milk and its products,
orange juice, infant formulas, and breakfast cereals.
Vitamin D can also be consumed as a dietary supplement in one of two forms: D2 and D3.
Vitamin D synthesis and metabolism.
Ultraviolet B radiation penetrates uncovered skin
and converts 7-dehydrocholesterol to pre-vitamin D3,
which in turn becomes vitamin D3.
Vitamin D may also be obtained from dietary sources or supplements.
Vitamin D3 binds to vitamin D binding proteins,
DBP, in the bloodstream,
and then activated first in the liver to become 25-hydroxy vitamin D,
and then in the kidney to 125-dehydroxy
vitamin D. The activated vitamin D binds to intracellular vitamin D receptor,
VDR, and its target tissues.