1. Open Education Resource: Vitamins- chemistry, sources and diseases
Work done as part of AICTE approved
FDP201x Pedagogy for Online and Blended Teaching-Learning Process
Lesson 4: Vitamin D – chemistry, sources and diseases
RC1128_Team 85
Dr. Zeenat N. Kashmiri, Department of Zoology
Dr. Sujata A. Mankar Department of Microbiology
OER on “Vitamins– chemistry, sources and diseases” by Department of Zoology and Microbiology, Dada Ramchand Bakhru Sindhu Mahavidyalaya, Nagpur (MS), India, is licensed under the Creative Commons Attribution-Share Alike 4.0 International License. You are free to use, distribute and modify it, including for commercial purposes, provided you acknowledge the source and share-alike.
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2. Vitamin D Learning Objectives Target Audience Tags of OER
Able to classify different types of vitamins
Explain deficiency diseases cause by vitamins
Understand role of vitamins
Identify foods that contain vitamins we needs daily
Target Audience
Undergraduate student those who opt Biological Sciences as one of the subject
Tags of OER
Vitamins, water soluble vitamin, sources, RDA, deficiency, diseases
Tools used in OER Creation
Power Point Presentation (ppt) to be uploaded on MOODLE site which is created as OER

3. Vitamin D Contents Introduction Chemistry of Vitamin D
Sources of Vitamin D
Recommendation (RDA)
Biochemical function
Diseases/Deficiency of Vitamin D
Practice questions
References

4. Vitamin D Introduction
Vitamin D is also known as antirachitis vitamin or calciferol or sunshine vitamin.
It is a fat-soluble vitamin
Vitamin D –precursor is cholesterol, converted by UV from sunlight exposure, therefore is a “non‐essential” vitamin
Vitamin D plays a critical role in the body’s use of calcium and phosphorous
Increases calcium absorption in bone, intestines, kidney
Promotes bone growth and maintenance.
Vitamin D benefits the body by playing a role in immunity and controlling cell growth
Children especially need adequate amounts of vitamin D to develop strong bones and healthy teeth

5. Vitamin D Chemistry of Vitamin D
Two main forms of the vitamin D were discovered
1. Ergocalciferol vitamin D2 is formed from ergosterol, present in plants
2. Cholecalciferol (vitamin D3) is found in animals, and is formed by irradiating the animal sterol, 7- dehydrocholesterol.
Both the sterols are similar in structure except that ergocalciferol has an additional methyl group and double bond.
Both these compounds are sources for vitamin D activity and are referred to as provitamins.
The synthesis of vitamin D3 in the skin is proportional to the exposure to sunlight. Dark skin pigment (melanin) adversely influences the synthesis of vitamin D3.
Fig.- Formation of ergocalciferol from ergosterol

6. Vitamin D Sources of Vitamin D
The primary food sources of vitamin D are milk and other dairy products fortified with vitamin D
It is found in abundance in cod liver oil and other fish oils (e.g., herring, salmon and sardines)
Moderate amounts in egg yolk and animal liver
Less quantities occur in milk
The vitamins D are actually a group of compounds. All are sterols, which occur in nature, chiefly in animals.
It is the only vitamin synthesized by man in sunlight. We obtain vitamin D through our skin which produces vitamin D in response to sunlight

7. Recommended Dietary Allowance (RDA)
Vitamin D
Recommended Dietary Allowance (RDA)
The Recommended Dietary Allowance (RDA) for vitamin D appears as micrograms (mcg) of cholecalciferol (vitamin D3)
From 12 months to age 50, the RDA is fixed at 15 mcg
20 mcg of cholecalciferol equals 800 International Units (IU), which is the recommendation for maintenance of healthy bone for adults over fifty
Exposure to ultraviolet light is necessary for the body to produce the active form of vitamin D
10 to 15 minutes of sunlight without sunscreen on the hands, arms and face, twice a week is sufficient to receive enough vitamin D
This can easily be obtained in the time spent riding a bike to work or taking a short walk
In order to reduce the risk for skin cancer one should apply sunscreen with an SPF of 15 or more, if time in the sun exceeds 10 to 15 minutes

8. Vitamin D Biochemical functions
Biologically active form of vitamin D is calcitriol (1.25- dihydroxycholecalciferol). It acts at three different sites, namely intestine, kidney and bone, and regulates plasma level of calcium and phosphate
Role on intestine. Calcitriol promotes the absorption of calcium and phosphate by the intestine. In the intestinal cells, calcitriol binds with cytosolic receptor to form a calcitriol-receptor complex, which in turn interacts with a specific DNA leading to the synthesis of calcium binding protein. This protein participates in the active transport of calcium across the small intestinal mucosa.
Role on bone and in growth. Calcitriol stimulates the calcium uptake by osteoblasts of bone for deposition as calcium phosphate. Thus, it is essential for bone formation, hence promotes growth in general.
Role on kidney. In the kidney calcitriol helps in excretion of calcium and phosphate
It promotes the normal functioning of parathormone
Vitamin D increases citrate content of bone, blood and other tissues
It exerts an anti-rachitic effect. Rickets is a disease involving bone growth

9. Vitamin D Vitamin D Deficiency Rickets
It is a common disease in infants where bones fail to calcify properly. It is characterized by softness of bones, owing to the irregular deposition of the calcium phosphate in the bones leading to bending of thelong bones and teeth. The ribs present a beaded appearance (ricketry rosary) at the costo-chondral junctions. The chest gives a pigeon-breast appearance. Teeth erupt late and are deformed. In rickets, the level of calcitriol decreases in plasma and alkaline phosphatase activity is elevated.
Vitamin D is the only vitamin, which can be synthesized by the body when exposed to sunlight, so its deficiency is relatively less common. However insufficient exposure to sunlight and consumption of vitamin D lacking diet results in deficiency. Rickets in growing children and osteomalacia in adults are produced by vitamin D deficiency.
Bowed legs
Beaded ribs

10. Vitamin D Vitamin D Deficiency Osteomalacia
It is a condition in adults similar to rickets in children. The disease is characterized by the softening of the bones especially the pelvic girdle and ribs in female leading to deformities. In case of pregnancy, where there is extra demand for the vitamin and drain of the vitamin due to accretion in milk, such a problem may occur. Here the bones become softer than in rickets and serum calcium is sometimes reduced to the extent that it may cause tetany.
Vitamin D is the only vitamin, which can be synthesized by the body when exposed to sunlight, so its deficiency is relatively less common. However insufficient exposure to sunlight and consumption of vitamin D lacking diet results in deficiency. Rickets in growing children and osteomalacia in adults are produced by vitamin D deficiency.

11. Vitamin D Vitamin D Toxicity
Liver is the storehouse of vitamin 'D' from where it is slowly metabolized
Among all vitamins, vitamin D is the most toxic in overdoses
Toxicity is manifested by nausea, headache, digestive troubles, weakness, polyurea and anorexia
Loss of calcium from bone and deposition in soft tissues.
Loss of appetite, nausea and vomiting, psychological depression.
Hypervitaminosis D may lead to formation of stones in kidney

12. Take a pause and answer the following question
Vitamin D
Take a pause and answer the following question
Practice Questions
1. Write down sources of Vitamin D .
2. What is RDA of vitamin D for adults and children ?
3. What are different biochemical functions of Vitamin D?
4. Describe the diseases causes by deficiency of Vitamin D.
5. What are the toxic effect vitamin D ?
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13. Vitamin D References Biochemistry – Satyanarayana
Animal Physiology – M. P. Arora
Vitamins by M. G. Rajanandh

14. Vitamin D
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