25 years ago, in 1991 COMA*dictated that vitamin D intake was far adequate from sunshine alone. 24 years on, this archaic idea is no more, and SACN** has devised new and improved requirements that truly optimise the role of the diet and dietary supplements in promoting bone health.
What is Vitamin D?
Vitamin D, the “Sunshine Vitamin” has two forms these are Vitamin D2 (Ergocalciferol) and Vitamin D3 (Cholecalciferol). D3 is the primary vitamin required for bone health.
Cholecalciferol is derived from UVB rays generated from the sun. Vitamin D production begins in the skin, formed from pro-vitamin D, it then undergoes multiple reactions before moving to the liver where it produces 25(OH)D. Finally it converts to the active form of Vitamin D, 1,25(OH)2D (Calcitriol), in the kidney.
Why is Vitamin D so important?
The recent “buzz” around Vitamin D is fitting due to the daily recommended values (DRVs) having increased ten-fold!Previous to 2015 it was believed that we could achieve our Vitamin D needs from sunshine alone. In 2015, through many hours of dedicated work SACN founded that all people over 4 years should consume 10mcg/day of Vitamin D, instead of the previous 0mcg/day.
Vitamin D is renowned for its contribution to density and strength of bone, and calcium absorption. It’s common knowledge that 99% of the calcium in the body is stored within the skeletal system. Pocock et al (1994) found that bone strength is dependent on the remodelling process . Bone remodeling is the work of 3 hormones, of which, Calcitriol is one. Many studies have shown that Vitamin D deficiency in young children has lead to the development of Rickets, which clinically manifests as bone deformities such as bowing of the legs. In adults this is called Osteomalacia, and is characterised by brittleness of bone. In addition, there has been minor evidence to show positive effects of Vitamin D on Atherosclerosis and Coronary heart disease (CHD).
Vitamin D3 Sources
The primary source of Vitamin D3 is sunlight. It’s thought that 15minutes/day in the sun is satisfactory for majority of your Vitamin D3 needs. However, in Winter (October-March) this is deemed inadequate.
Furthermore, Vitamin D is made in the skin and liver of all animals thus, can be consumed by eating said animal. Great dietary sources include, animal liver, cod liver oil, oily fish (salmon and tuna), milk, and cheese. Vitamin D is also plant derived such as in sunflower seeds and oil . Nevertheless, many of these sources contribute small amounts of Vitamin D. A normal portion of tinned tuna contains only 3.85mcg of vitamin D. In addition, evidence has shown poor intakes of these food sources. A pitiful 4-5% of people aged 4-18 years consumed oily fish. 
Don’t despair, there are other options. A thriving supplement on the current market is the Vitamin D3 and K2 (MK7) tablet. As complicated as it may sound its actions are simple, yet effective in promoting strength and long-life health of bones. Moreover, a study showed Vitamin D3, K2(MK7) supplements significantly decreased the age-related decline of bone mineral composition in 244 postmenopausal women (Theuwissen, et-al, 2013). 
Vitamin K2 is a fat soluble vitamin known as Menaquinone. There are nine forms of Menaquinone, e.g, MK1-9. MK7 is ring molecule with a protruding 7 carbon chain. MK7 is converted from Vitamin K1 by endemic gut E.coli. In addition to Vitamin K2’s blood clotting properties, it also plays a vital role in bone structure. Vitamin K undergoes a chemical reaction to form an amino acid “Gla”. Gla then differentiates to 5 proteins using bone forming osteoblasts. If Vitamin K is low then Gla cannot be activated for bone remodeling, which can lead to osteoporosis. According to Theuwissenn, et al. (2012) majority of the population do not consume enough Vitamin K to promote Gla production, thus leading to a need for supplementation. Those most at risk of diet induced bone disease are menopausal women, the elderly, young children and the house bound. 
Now it’s up to you...
- Increase your dietary intake of Vitamin D. Try consuming more oily fish and switching to sunflower oil.
- Try to get at least 15minutes per day, of uncovered exposure to sunshine.
- Take your supplements, the PHE*** recommend that “everyone” should consider taking a daily vitamin D supplement. For optimal bone health, we suggest a Vitamin D3 and K2(MK7) tablet: Link Here
*COMA-Committee on Medical Aspects of Food and Nutrition
**SACN- Scientific Advisory Committee on Nutrition
*** PHE- Public Health England
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- NHS. (2015).Rickets and osteomalacia.Available: http://www.nhs.uk/Conditions/Rickets/Pages/Introduction.aspx.
- Weber.P. (2001). Vitamin K and Bone.Nutrition. 17 (10), Pg. 880-887.
- PJT. (2015).Published Research-Bone.Available: http://www.k-vitamins.com/index.php?page=Bone.
- Knapen MHJ, Drummen NE, Smit E, Vermeer C, Theuwissen E. Three-year low-dose menaquinone-7 supplementation helps decrease bone loss in healthy postmenopausal women. Osteoporosis Int. 2013 Sep;24(3):2499-507.
- The Vitamin D Council. (2007). It's the Sunshine Vitamin.Available: http://www.sunshinevitamin.org/
- The Office of Dietary Supplements. (2011).Vitamin D.Available: https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/.
- SACN. (2015). Appendix 2 Chapter 8 Dietary vitamin D intakes and plasma 25 hydroxyvitamin D concentration of the UK population tables. Available: https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/447405/Appendix_2_-_Chapter_8_NDNS_intake_tables_.pdf.
- SACN. (2015). Draft Vitamin D and Health Report. Available: https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/447402/Draft_SACN_Vitamin_D_and_Health_Report.pdf.
- Pocock et-al. (1994). Prediction of bone density from vitamin D receptor alleles. Nature. 367 (10), Pg. 284-287
- Truswell.S. (2012). 15: Vitamin D and K. In: Mann,J. Truswell,S.Essentials of Human Nutrition. 4th ed. Oxford: Oxford University Press. Pg. 246-253.