**Vitamins are complex organic molecules(a molecule closed of carbon-hydrogen bonds) which are micro nutrients that are needed by an organism for proper metabolism.**

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### INTRODUCTION
It is a micronutrient in the fact that it needs to be taken in small quantities. They cannot be synthesized by most organisms, and the organisms that have the ability cannot synthesize in sufficient quantity. The word vitamin is derived from "vitamine", which was coined by a Polish biochemist called Casimir Funk in the year 1912. Before the year 1935, there were no vitamin supplements, vitamins were gotten only from food, then vitamin B complex and vitamin C were produced. In the 1950s, the government made sure that vitamins were added to food like milk and bread(this is known as food fortification). A lot of vitamins are not single molecules, but are groups of related compounds known as vitamers. For example; the vitamers of vitamin A include retinol, retinal, retinoic acid and beta-carotene, etc. They are collectively known as retinoids. The vitamers of vitamin E include the Tocopherols and Tocotreniols.

### CLASSIFICATION
        Vitamins are classified into fat soluble and water soluble vitamins. 
                                ** Water soluble vitamins:** 
These are vitamins that are soluble in water. They are easily absorbed in tissues. They are easily excreted from the body because they cannot be stored. Therefore they need to be constantly replenished in our diet. The examples of water soluble vitamins are:

 **  A. Vitamin B-complex group:** under this, we have;
I. Vitamin B1
II. Vitamin B2
III. Vitamin B3
IV. Vitamin B5
V. Vitamin B6
VI. Vitamin B7
VII. Vitamin B9
VIII. Vitamin B12
  
**B. Vitamin C**

**Fat-soluble vitamins**
These are vitamins that are soluble in fat and can't dissolve in water. They are abundant in high fat foods. They are absorbed by the intestine with the help of fats. They are stored in the liver and adipose tissue, therefore they are not excreted easily. So if there is an excess intake, it leads to "HYPERVITAMINOS".
  The examples of fat soluble vitamins are:
a. Vitamin A
b. Vitamin D
c. Vitamin E
d. Vitamin K

### Types of Vitamins and Common sources
There are thirteen types of vitamins, and they are:
1.	Vitamin A (Retinol): found in green leafy vegetables, nuts, tomatoes, oranges, ripe yellow fruits, etc.
2.	Vitamin B1 (Thiamine): found in fresh fruits, corn, cashew, potato, peas, wheat, milk, etc.
3.	Vitamin B2 (Riboflavin): found in bananas, grapes, mangoes, peas, pumpkin, dates, liver, milk, etc.
4.	Vitamin B3 (Niacine): found in meat, eggs, fish, milk, guava, mushroom, peanut, etc.
5.	Vitamin B5 (Pantothenic acid): found in meat, kidney, egg yolk, broccoli, peanuts, fish, chicken, etc.
6.	Vitamin B6 (Pyridoxine): found in pork, chicken, fish, bread, cereals, eggs, etc.
7.	Vitamin B7 (Biotin): found in walnuts, peanuts, cereals, milk, egg yolk, salmon, etc.
8.	Vitamin B9 (Folic acid): found in citrus, green leafy vegetables, legumes, beets, etc.
9.	Vitamin B12 (Cobalamin): found in citrus fruits, broccoli, black currants, chestnuts, etc.
10.	Vitamin C (Ascorbic acid): found in citrus fruits, brocolli, black currants, chestnuts, etc.
11.	Vitamin D (Calciferol): found in fish, beef, cod liver oil, egg yolk, liver, etc.
12.	Vitamin E (Tocopherol): found in potatoes, pumpkin, guava, mango, milk, etc.
13. Vitamin K (Phytonadione): found in tomato, broccoli, mango, grapes, chestnuts, etc.

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## Functions of Vitamins
1.	Vitamin A: essential for bone and tooth formation. It also aids in vision and immune. It keeps the intestines in good working condition.
2.	Vitamin B1: It helps in nervous coordination and also aids in releasing energy from food.
3.	Vitamin B2: It helps with good vision and healthy skin. It also helps convert tryptophan an amino acid into niacin.
4.	Vitamin B3: aids in metabolism, normal enzyme function and promoting healthy skin and nerves.
5.	Vitamin B5: aids in metabolism and hormone formation.
6.	Vitamin B6: helps in protein metabolism, product of red blood cell, insulin and haemoglobin.
7.	Vitamin B7: releases energy from carbohydrates and helps in metabolism.
8.	Vitamin B9: helps in protein metabolism and red blood cell formation. It can also reduce the risk of neural tube birth defects.
9.	Vitamin B12: aids in production of red blood cell and nervous system coordination.
10.	Vitamin C: helps in wound healing, bone formation and collagen synthesis. It also helps in boosting the immune system.
11.	Vitamin D: helps in bone and tooth formation by encouraging absorption and metabolism of phosphorus and calcium.
12.	Vitamin E: it is an antioxidant that fights infection and keep red blood cells healthy.
13.	Vitamin K: it helps in blood clotting and also keep bones healthy.

## Deficiencies and excessive intake of Vitamins
VITAMINS	DEFICIENCY	EXCESSIVE INTAKE
A	Night blindness, keratomalacia, weak immune system	Hypervitaminosis
B1	Beri Beri, Wernickekorsakoff syndrome	Drowsiness and muscle relaxation
B2	Ariboflavinosis, glossitis, angular stomatitis	Diarrhea
B3	Pellagra	Liver damage
B5	Paresthesia	Diarrhea, nausea and heartburn
B6	Anemia, peripheral neuropathy	Impairment of proprioception, nerve damage
B7	Dermatitis, enteritis	Skin rash
B9	Megloblastic anemia, neural tube defect	Mask symptom of Vitamin B12 deficiency

B12 	Deficiency anemia	None proven
C	Scurvy (affected pirates because they couldn't carry perishable fruit on their ship)	Stomach pain, diarrhea
D	Rickets and osteomalacia	Hypervitaminosis D
E	Hemolytic anemia in newborn infants	Congestive heart failure
K	Bleeding diathesis	Decreased anticoagulation of warfarin

### Antivitamins 
They are compounds that oppose the absorption and action of vitamins. For example, avidin protein found in raw egg white inhibit the absorption of biotin.

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<center>Written by @weirdestwolf - a medical doctor</center>
<center>All images used are copyright free</center>