Vitamin D is a biggie!! When we talk about repair and disease prevention we can’t go past this quiet achiever.
Although we refer to it as a vitamin, vitamin D actually acts more like a hormone. It is a chemical made in one part of the body that causes actions in another part of the body.... which is pretty much the definition of a hormone. It has an enabling rather than causative function and is used in the cells of the body to enable repair. Without enough vitamin D, the cells are unable to counter the effects of the genetic and environmental damage we face each day.
For many years the role of Vitamin D status has been well understood in the metabolism of skeletal health, particularly its role in the cellular uptake of calcium, magnesium and phosphorous. Historically, vitamin D deficiency resulted in the skeletal disease rickets but that is rare today. Instead, low levels can go unnoticed until the body can no longer repair.
It is essential for all body systems: the immune system, brain and nervous system, pancreas, skin, muscles and cartilage and the reproductive system. It is estimated that around 1 billion people are seriously deficient and a large number are lacking.
About 50% to 90% of vitamin D is absorbed through the skin via sunlight while the rest comes from the diet. Twenty minutes of sunshine daily with over 40% of skin exposed is required to prevent vitamin D deficiency (Sizar, Omeed; Khare, Swapnil; Goyal, Amandeep; Givler, Amy, 2022). Today we spend less time exposed to the sun and when we do we cover up or apply sunblock. UVB is needed to make vitamin D and for this to happen sunlight must reach the skin for a short time each day.
“The term ‘vitamin D’ specifically refers to the parental vitamin D produced endogenously by the action of sunlight on 7-dehydrocholesterol in skin (also known as vitamin D3, or cholecalciferol), or obtained from dietary foodstuffs as either vitamin D3 or vegetable vitamin D2 (also known as ergocalciferol)." (Hewison, 2012). Small amounts can be found in fatty fish such as herring, salmon, sardines and tuna, beef and liver, butter, eggs, and fortified foods such as milk (Lesley Braun, 2015).
Ultraviolet rays from the sun cause the precursor in the skin to convert to pre-vitamin D3. This chemical slowly absorbs into the body and with the body’s heat is converted to the active calcitriol over the next 36 hours. From there it is distributed to the cells throughout the body.
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Hewison, M. (2012). An update on vitamin D and human immunity. Clinical Endocrinology, 76(3), 315-325. doi: https://doi.org/10.1111/j.1365-2265.2011.04261.x
Lesley Braun, M. C. (2015). Herbs and Natural Supplements. Sydney: Elsevier.
Sizar, Omeed; Khare, Swapnil; Goyal, Amandeep; Givler, Amy. (2022). Vitamin D Deficiency. Statpearls.