Vitamin D3 Deficiency And Insufficiency
What Is Vitamin D3, How Is It Formed?
Vitamin D3 (cholecalciferol); It is a fat-soluble vitamin that is produced in the skin when exposed to sunlight. Ultraviolet B (UVB) rays form vitamin D3 (cholecalciferol) photochemically from 7 dehydrocholesterol in the skin. Vitamin D3 is converted into inactive products with excessive exposure to sunlight.
Since Vitamin D3 can be synthesized biologically, it is also referred to as a hormone. Vitamin D3 can also be obtained with fatty fish, liver, mushrooms processed with ultraviolet rays, etc. 1 2
Vitamin D3, made on the skin or taken on a diet, is not biologically active. It is transformed in the liver and then converted in the kidneys, turning into a biologically active form, 1.25 (OH) 2D], also known as calcitriol. 1 2
Functions of Vitamin D
Activated vitamin D3 has many biological functions. Its most important effect is on calcium, phosphorus metabolism and bone mineralization1. In the absence of vitamin D, only 10-15% of calcium and 60% of phosphorus in the diet can be absorbed. In the presence of vitamin D, this ratio increases to 30-40% for calcium and 80% for phosphorus. 1 2 3
Other possible roles of 25 (OH) 2 D include increasing bone resorption, decreasing PTH synthesis and release, increasing insulin production, reducing renin synthesis, increasing myocardial contractility. Active vitamin D also functions to regulate the immune response by activating, cytokine release by activating T lymphocytes, activating B lymphocytes, and a substance called kathelicidine, which increases Ig synthesis. 1 2 3
Active vitamin D controls more than 200 genes, which focus on cell proliferation, differentiation, apoptosis and angiogenesis.1,2,3
It is now generally accepted that vitamin D deficiency and deficiency is associated with many chronic diseases including common cancers, cardiovascular diseases, metabolic syndrome, infectious and autoimmune diseases, and is a worldwide health problem. 1,2,3
Vitamin D3 Deficiency And Insufficiency
25(OH) Vitamin D levels in the blood under 20 ng/mL is accepted as Vitamin D deficiency, levels between 21-29 ng/mL as insufficiency, over 30 ng/mL as sufficient levels and over 150 ng/mL as Vitamin D intoxication. 4
Main Conditions with Low 25 (OH) D Levels
Dark-skinned people, aging, low exposure to the sun (indoor dressing, indoor environment, improper angle of sun, use of sunscreen, etc.) obesity, disorders related with malabsorption (Cystic fibrosis Celiac disease, whipple disease, Crohn's disease etc.), with the use of specific drugs (anticonvulsant drugs, glucocorticoids, etc.), liver failure , increase in 25 (OH) D excretion, nephrotic syndrome, chronic kidney failure, hyperphosphatemia, genetic diseases, tumor-induced osteomalacia, some granulomatosis diseases (sarcoidosis tuberculosis, some lymphomas), hyperthyroidism, pregnancy, infants who are fed breast milk poor in vitamin D.1,4
Clinical Symptoms of Vitamin D Deficiency
Rickets, which is associated with vitamin D deficiency in childhood (usually below 5 ng / mL), is characterized by bone mineralization disorder, pain in the legs, delay in walking, and disorders in the joints of the cartilage joints. Vitamin D deficiency causes osteomalacia in adults. The most prominent complaint in osteomalacia is widespread pain and proximal muscle weakness. Low vitamin D levels can lead to secondary hyperparathyroidism, causing osteopenia and osteoporosis, increasing the risk of fractures.5
Approach to Vitamin D Deficiency Prevention and Treatment
To prevent vitamin D deficiency, the Institute of Medicine (IOM) recommends, that infants should immediately receive a daily supplementation of vitamin D of 400 IUs during the first year of life. Individuals between 1 and 70 years should receive 600 IU of vitamin D daily and adults >70 years should receive a daily dose of 800 IU vitamin D. The doses recommended by IOM will likely increase the 25(OH)D level to 20 ng/mL, which they considered to be adequate for bone health, but not to levels >30 ng/mL, as recommended by the Endocrine Society. That’s why the Endocrine Society recommended in its Practice Guidelines that infants during their first year of life receive a daily supplementation of 400–1000 IU (up to 2000 IU is safe), children and adolescents between 1 and 18 years a daily supplementation of 600–1000 IU (up to 4000 IU is safe), and adults >18 years a daily supplementation of 1500–2000 IU (up to 10,000 IU is safe) for the prevention of vitamin D deficiency. However, obese individuals, patients with malabsorption syndromes, and patients on glucocorticoids, anti-seizure medications may require higher doses of vitamin D than individuals without these conditions.2
Vitamin D deficiency / insufficiency is common in our country (Turkey) and in the world. Today, it is obvious that sun rays are not sufficiently utilized for various reasons, and in this case, the foods that are enriched with vitamin D or vitamin D supplement treatment increase.2
Treatment Methods for Vitamin D Deficiency
In case of deficiency or deficiency of vitamin D3, diet, sunlight exposure and taking vitamin D3 supplements are frequently recommended. One of the most used methods is vitamin D3 supplements. It is usually administered orally or by injection. Vitamin D is an oil-soluble molecule. Absorption efficiency or bioavailability depends on the lipid composition and carrier (solvent) of the food supplement. Dissolved formulations, which are commercially available, dissolve mostly in oil-based solvents. There are a variety of natural oils. 8
The amount needed to treat vitamin D deficiency or deficiency varies depending on the severity of the deficiency and individual health risks. While it is aimed to bring your vitamin D levels to a safe range and prevent its decrease, the most appropriate treatment option and dosage is determined by your doctor.
References:
1. Nair R, Maseeh A. Vitamin D: The "sunshine" vitamin. J Pharmacol Pharmacother. 2012;3(2):118‐126. doi:10.4103/0976-500X.95506
2. Fidan F, Alkan BM, Tosun A. Çağın Pandemisi: D Vitamini Eksikliği ve Yetersizliği. Turk J Osteoporos 2014;20:71-74.
3. Öngen B, Kabaroğlu C, Parıldar Z. D Vitamini’nin Biyokimyasal ve Laboratuvar Değerlendirmesi. Ege Üniversitesi Tıp Fakültesi, Türk Klinik Biyokimya Dergisi 2008; 6: 23-31
4. Vitamin D Deficiency Medical Progress Michael F. Holick. The New England Journal Of Medicine. Boston: Jul 19, 2007 Vol. 357, Iss. 3; pg. 266.
5. Holick MF, Binkley NC, Bischoff-Ferrari HA, et al. Evaluation, treatment, and prevention of vitamin D defciency: an Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab 2011; 96: 1911-30.
6. Ross AC, Manson JE, Abrams SA, et al. The 2011 report on dietary reference intakes for calcium and vitamin D from the Institute of Medicine: what clinicians need to know. J Clin Endocrinol Metabol 2011; 96: 53-8.
7. Cosman F, De Beur SJ, LeBoff MS, et al. Clinician’s guide to prevention and treatment of osteoporosis. Osteoporosis Int 2014; 25: 2359-81.
8 Šimoliūnas E, Rinkūnaitė I, Bukelskienė Ž, Bukelskienė V. Bioavailability of Different Vitamin D Oral Supplements in Laboratory Animal Model. Medicina (Kaunas). 2019 Jun 10;55(6):265. doi: 10.3390/medicina55060265. PMID: 31185696; PMCID: PMC6631968.
