Vitamins -Definition, types, 9 functions, 8 sources and 8 side effects of vitamin


Vitamins -Definition, types, 9 functions, 8 sources and 8 side effects of vitamin

Vitamins are a very significant part of a food and form a very important part of our diet. They have been made to different forms that can even be taken in as medicine when needed. What exactly are vitamins and why are they so important to us?


Vitamins are a group of organic compounds essential for cellular function, growth, and nutrition which are required in small quantities and are not produced in the body.

This definition tells us that it is very important for us to consume vitamins because our bodies are unable to produce them from any source other than our diet.

Vitamins in the human body

There are 13 vitamins in all; 4 of which are fat-soluble, and the remaining 9 being water-soluble. Vitamins A, D, E and K are fat-soluble, while others are soluble in water. These vitamins include

  • Vitamin A – Retinol
  • Vitamin B1 – Thiamine
  • Vitamin B2 – Riboflavin
  • Vitamin B3 – Niacin
  • Vitamin B5 – Pantothenic acid
  • Vitamin B6 – Pyridoxine
  • Vitamin B7 – Biotin
  • Vitamin B9 – Folic acid
  • Vitamin B12 – Cobalamin
  • Vitamin C – Ascorbic acid
  • Vitamin D – Ergocalciferol
  • Vitamin E – Tocopherol
  • Vitamin K – Phytonadione

Functions of Vitamins

  • Vitamin A – Retinol plays a very important role in vision, especially vision in the dark. It also maintains our body tissues and mucus membrane lining.
  • Vitamin B1 – Thiamine is important in the process that converts carbohydrates to useful energy. It is also important in the transmission of signals in nerves, and as well plays a significant role in muscle contraction. Thiamine is present in the body as Thiamine Pyrophosphate (TPP)
  • Vitamin B2 – Riboflavin is present in the body as Flavine mononucleotide (FMN) and Flavin Adenine dinucleotide (FAD), which are coenzymes important in reactions that involve removal of water. It helps red blood cell production.
  • Vitamin B3 – It is also known as nicotine or nicotinic acid and is present in the body as either Nicotinamide adenine dinucleotide (NAD) or Nicotinamide adenine dinucleotide phosphate (NADP); both of which are coenzymes involved in several reactions that occur in the body. It helps to reduce tiredness, helps production of glucose, and helps the brain in psychosocial function.
  • Vitamin B5 – Pantothenic acid is majorly responsible for preventing clots from forming in blood vessels, as well as keep the vessels dilated. Its active form is coenzyme A.
  • Vitamin B6 – Pyridoxine’s active form is pyridoxal phosphate (PLP) which is involved in several reactions such as the formation of heme, a constituent of haemoglobin. It is also needed for nervous function and it plays a role in making antibodies to aid the body’s immunity.
  • Vitamin B7 – Biotin is useful in fat, carbohydrate, and protein metabolism.
  • Vitamin B9 – Folic acid has several functions; being very important in the formation of tissues in the fetus. The coenzyme form of Vitamin B9 is tetrahydrofolate which plays a major role in the synthesis of nucleotides.
  • Vitamin B12 – Cobalamin helps prevent the body from megaloblastic anaemia. It helps to maintain a healthy nervous system and blood.

Sources of Vitamins

Vitamins are contained in a variety of diets; almost every food you consume contains vitamins. A few of these sources are highlighted below:

  • Eggs
  • Meat
  • oranges
  • carrots
  • sweet potatoes
  • tomatoes
  • bell pepper
  • green vegetables, etc

Deficiency of Vitamins

When either of the enlisted vitamins above is lacking, what are the side effects?

  • Deficiency of Vitamin B1 (retinol) though rare will lead to night blindness. Patients will be unable to see clearly in the absence of light.
  • Vitamin B2 (Riboflavin) deficiency may present with hair loss, itchy or sore throat, skin problems, sores at the mouth, etc.
  • In Vitamin B3 (Niacin) deficiency, there may be diarrhea, sores, tiredness, indigestion, etc. A disease known as pellagra is also a characteristic feature of deficiency of this vitamin; It usually presents with itchy skin.
  • Deficiency of Vitamin B5 (Pantothenic acid) may lead to stomach ache, vomiting, respiratory infections, nausea, depression, etc.
  • In deficiency of pyridoxine (Vitamin B6), synthesis of heme is impaired, and this may lead to pernicious anaemia.
  • When there is a deficiency of Biotin, it may lead to mild depression, hair loss, red itchy rashes, etc.
  • Deficiency of Vitamin B9 (Folic acid) will lead to neural tube diseases; the most common being anencephaly (absence of the brain) and spina bifida (failue of the spinal cord to function properly).
  • Megaloblastic anaemia is seen when Vitamin B12 is lacking; it leads to production of red blood cells that are abnormally large in size.
Igbaji Ugabi Chinwendu, from Cross River State, Nigeria. As a Business Educator, he is profoundly interested in teaching and managing business. Started blogging 2010 and officially 2013. He holds the esteemed positions of Chief Executive Officer (CEO) and Director at Freemanbiz Communication and Writers King LTD, demonstrating his leadership and expertise in the field.

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