Back to School: 10 Things You May Not Know About Vitamin D

Nutritionist Marianna Sulic's top ten things you might not know about Vitamin D!

1. Vitamin D is actually a hormone, not a vitamin. Scientists reclassified vitamin D as a hormone rather than a vitamin after researchers in the early 70’s learned that vitamin D was metabolised in the liver and kidneys, and it controlled calcium levels in the blood through its action in the intestines.
2. The greatest source of Vitamin D is from UVB sun exposure, however, with many years of warning about the dangers of sun exposure creating skin cancer we have covered up with sunscreen. Our skin cannot absorb vitamin D from the sun if we are wearing sunblock lotions.
3. UVB rays cannot penetrate glass or clothing, so you do not produce vitamin D just by sitting near a window.
4. There are 3 forms of vitamin D:
   1.Cholecalciferol - called D3: from the sun and supplements
   2. Calcidiol - called 25D: metabolised in the liver from D3
   3. Calcitriol - the active form called 1,25D3: metabolised in the kidneys from 25D and also metabolised by organs, tissues and cells from 25.
5. Cholecalciferol (D3) is naturally made in the body in large quantities when UVB rays hit the skin. Once you have made about 20,000 IU of vitamin D3, a mechanism in the skin destroys excess amounts so you will not become toxic. You can make up to 3,000IU of vitamin D in 12 minutes with bare arms and legs exposed at noonday sun or 20,000 IU of vitamin D by spending 30 minutes in the midday sun in a bathing suit.
6. The discovery that most tissues, organs and cells of the body have the ability to metabolise 25D from the liver and turn it into 1,25D3 means that Vitamin D circulates throughout the body and has the ability to land on receptor sites and affect the cells, tissues and organs that receive the vitamin D. Researchers are finding that it has many repair and maintenance functions and vitamin D is not just about healthy bones anymore.
7. Vitamin D deficiency is now connected, not only with osteoporosis, but with 17 varieties of cancers, along with heart disease, high blood pressure, strokes, autoimmune diseases, diabetes and chronic pain.
8. If you live above 35 degrees latitude, you will not be able to make vitamin D from the sun from approximately November to March, no matter how long you are exposed.
9. Pollution in the air can block UVB rays from the sun, thereby inhibiting your ability to make vitamin D. Also, UVB light, which is necessary for the production of vitamin D, is cut in half by cloud cover.
10. Vitamin D experts recommend that without sufficient sun exposure, children from age one and up should take at least 1,000IU/day of vitamin D. As they approach their teens and into adulthood this can be increased to 2,000IU/day.

Everyone can optimise their blood vitamin D levels to the ideal range of 100nmol/L by having sun exposure, taking the correct dosage in supplements and occasionally testing blood levels with their GP making sure to stay in range.

Reference: “The Vitamin D Revolution”, Soram Khalsa M.D.