Vitamin D Simplified

24 Aug 2016
Author: Lindsay Johnson
Read time: 7 min
Category: Archive

Vitamin D is the sunshine vitamin, which is a fat-soluble vitamin that functions as a prohormone (hormone precursor). Vitamin D is synthesized in the skin from 7-dehydrocholesterol after exposure to UVB rays. Vitamin D3 (also known as cholecalciferol) occurs naturally in small amounts in foods such as, sunflower sprouts, fenugreek sprouts, shiitake mushrooms, basil and sweet potatoes. Vitamin D itself is biologically inactive, and must undergo two hydroxylation reactions to become active. Vitamin D is first hydroxylated in the liver to form 25-hydroxyvitamin D (25[OH] D). It is further hydroxylated in the kidneys to 1, 25-dihydroxyvitamin D (1, 25[OH] 2D), the biologically active form of the vitamin.

Vitamin D has many benefits:

  • Enhances the intestinal absorption of calcium and phosphorus
  • Promotes bone mineralization
  • Involved in regulating serum calcium and phosphorus levels.
  • Plays a role in neuromuscular function
  • Influences cellular growth and differentiation.
  • Modulator of immune function, vitamin D may help prevent both infections and autoimmune diseases.
  • Inhibits cancer growth through multiple mechanisms; it inhibits IGF-1 (insulin growth factor) stimulated growth; it arrests the cancer cell growth cycle. Also, many cancer cells have vitamin D receptors, which inhibit cell growth when bound to vitamin D.

One of the leading vitamin D researchers, Dr. Michael Holick, estimates that 50 percent of the general population is at risk of vitamin D deficiency and insufficiency. Severe vitamin D deficiency in children causes rickets, which is characterized by softening and deformities of bones, muscle weakness, and dental abnormalities. Vitamin D deficiency in adults causes osteomalacia, which is characterized by softening of bones, bone pain, and muscle weakness. Arm and leg muscle weakness may be an early sign of vitamin D deficiency, and severe impairment of muscle function may occur before any signs of bone disease develop.[1],[2] Other manifestations of vitamin D deficiency may include chronic low back pain, diffuse aches and pains and fatigue.[3],[4]

Risk factors for vitamin D deficiency [5],[6] include living above 35 degrees latitude or in areas with tall buildings or a lot of atmospheric pollution;[7] being elderly or obese; having dark skin; avoiding sunlight exposure (by staying indoors, wearing protective clothing outdoors, using sunscreen); having low dietary vitamin D intake; having a condition that causes malabsorption (such as primary biliary cirrhosis, Crohn’s disease, pancreatic insufficiency, small-intestinal bacterial overgrowth, or a history of gastrointestinal surgery);[8],[9],[10]; being an ethnic minority living in Europe;[11],[12]and being an exclusively breast-fed infant not receiving vitamin D supplements.

The association between living at high latitude and vitamin D deficiency is due to the fact that at high latitudes the angle of the sunlight is very oblique. As a result, the light must pass through more ozone, which absorbs the wavelengths that stimulate cutaneous vitamin D synthesis. The association between air pollution and vitamin D deficiency results from the fact that ultraviolet light is blocked by air pollutants. The association between advancing age and vitamin D deficiency is due in part to a decreased capacity of aging skin to synthesize vitamin D. The association between obesity and low vitamin D status can be explained by decreased bioavailability of vitamin D from cutaneous and dietary sources because of its deposition in body fat.[13]

Sunlight exposure is a great source of vitamin D because the sun provides beneficial UVB wavelengths that are needed to optimize your levels. Once you get the proper amount of sunlight, your body will stop producing vitamin D because of its self-regulating mechanism. Expose yourself to direct sunlight for short periods of time to produce vitamin D3. Fair-skinned people can potentially max out their vitamin D production in just 10 to 20 minutes. However, if you have darker skin, you likely need to remain in the sun longer. If you plan to be in the sun for longer periods of time, I recommend using a safe sunblock such as Obvita Organic Sunscreen from Hippocrates.

If you get sunburned, aloe vera or argentyn silver gel are some of the best remedies to help repair your skin. The aloe has gel inside that is loaded with powerful glyconutrients that will help induce healing. When UVB rays hit the surface of your skin, your skin will then convert a cholesterol derivative, which will turn into vitamin D3. It can take up to 48 hours before the vitamin D3 penetrates into your bloodstream. If you shower immediately after sun exposure, you risk washing away the vitamin D3 formed by your skin and potentially reduce the benefits of sun exposure.

While those living in tropical regions have an abundance of sunshine, there are individuals who hardly have exposure, especially in most of the continental US. It doesn’t make much sense to expose your skin to the sun when the temperature is lower than 50 degrees F, which has a scarcity of UVB rays. This occurs a lot in most regions in the United States.

In addition, some studies have suggested that maintaining serum 25(OH) D levels in an “optimal” range could enhance bone health, dental health, and lower-extremity function, and reduce the risk of falls, fractures, some cancers, and possibly certain autoimmune diseases. An integrative medical doctor can assess what your optimal vitamin D levels should be, based on your specific needs.

To order your vitamin D:

[1] Glerup H, Mikkelsen K, Poulsen L, et al. Hypovitaminosis D myopathy without biochemical signs of osteomalacic bone involvement. Calcif Tissue Int 2000;66:419–424.

[2] Prabhala A, Garg R, Dandona P. Severe myopathy associated with vitamin D deficiency in western New York. Arch Intern Med 2000;160:1199–1203.

[3] Al Faraj S, Al Mutairi K. Vitamin D deficiency and chronic low back pain in Saudi Arabia. Spine 2003;28:177–179.

[4] Gloth FM III, Lindsay JM, Zelesnick LB, Greenough WB III. Can vitamin D deficiency produce an unusual pain syndrome? Arch Intern Med 1991;151:1662–1664.

[5] Bergstrom WH. Calciferol deficiency here and now. Am J Dis Child 1975;129:1137–1138.

[6] Ziegler EE, Hollis BW, Nelson SE, Jeter JM. Vitamin D deficiency in breast-fed infants in Iowa. Pediatrics 2006;118:603–610.

[7] Agarwal KS, Mughal MZ, Upadhyay P, et al. The impact of atmospheric pollution on vitamin D status of infants and toddlers in Delhi, India. Arch Dis Child 2002;87:111–113.

[8] Sitrin M, Meredith S, Rosenberg IH. Vitamin D deficiency and bone disease in gastrointestinal disorders. Arch Intern Med 1978;138:886–888.

[9] Kozawa K, Imawari M, Shimazu H, et al. Vitamin D status after total gastrectomy. Dig Dis Sci 1984;29:411–416.

[10] Hill M. Normal and pathological microbial flora of the upper gastrointestinal tract. Scand J Gastroenterol 1985;Suppl III:1–5.

[11] Ellis G, Woodhead JS, Cooke WT. Serum-25-hydroxyvitamin-D concentrations in adolescent boys. Lancet 1977;1:825–828.

[12] Datta S, Alfaham M, Davies DP, et al. Vitamin D deficiency in pregnant women from a non-European ethnic minority population—an interventional study. BJOG 2002;109:905–908.

[13] Wortsman J, Matsuoka LY, Chen TC, et al. Decreased bioavailability of vitamin D in obesity. Am J Clin Nutr 2000;72:690–693.

Article by Tom Fisher RN, BA

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