Vitamins: Characteristics, Classification and Properties

Vitamins are organic compounds that animal bodies require in small quantities. Animal bodies cannot synthesize vitamins and so rely on their diet to obtain them. There are different types of vitamins. Here, we will see the classification of vitamins with examples.

Retinol, otherwise known as Vitamin A was the first one to be discovered. 

The body needs vitamins to help with various metabolic activities, growth in children, and to maintain health. Vitamins are involved in activities such as the formation of nervous and blood cells, the production of hormones, catalysts, etc. Deficiency of vitamins could slow down or cease these activities. 

Characteristics of Vitamins

• Vitamins are widely seen in both plants and animals.
• Plants can synthesize vitamins but animals rely on their diet.
• Most food items will have more than one vitamin in them.
• The vitamins that the human body can synthesize are
  • Vit A from carotene
  • Vit D from ergosterol and 7-dehydrocholesterol under UV radiation from the sun
    • Some B vitamins are synthesized by microbes in the intestine.
    • Vit C is produced in rats
• Every cell in the animal body can store vitamins but only for a specific period.
• They can perform their duties in low concentrations as their degradation process is slow.
• Vitamins are non-antigenic.
• The unused vitamins are either destroyed or excreted from the body.
• Many vitamins are synthesized artificially in the labs.

Classification of Vitamins with Examples

Based on their solubility, and ability to be absorbed, vitamins are categorized into fat-soluble and water-soluble. 

Fat-soluble Vitamins

• They are oil-based hydrophobic compounds stored in the liver.
• Liver cells can store Vit A for up to 6 months and Vit D for 2 months.
• They are made up of carbon, hydrogen, and oxygen.
• The body needs the assistance of bile salts and fats to absorb them.
• The body cannot store these vitamins so an excessive intake could be toxic and can cause hypervitaminosis.
• Examples are Vit A, Vit D, Vit E and Vit K.

Fat-soluble vitamins have specialized roles in animals, depending upon their activities. 

• Vit A is a visual pigment
• Vit D helps absorb calcium and phosphorous
• Vit E protects mitochondria from being inactive
• Vit K helps in blood clotting in vertebrates

Water-soluble Vitamins

• These vitamins are made of carbon, hydrogen, oxygen, and nitrogen.
• The body does not store these water-soluble vitamins which are required on a daily intake basis.
• These vitamins are universal in function as most of them have more or less the same duties.
• They form catalytic factors to link the chains of molecules in biochemical reactions.
• Their deficiency could lead to symptoms and diseases.
• All water-soluble vitamins except lipoic acid are coenzymes.
• B vitamins are water-soluble and are required daily in small amounts.

Additional Reading

• Types, Properties & Biological Functions of Lipids
• Characteristics of Amino Acids
• Classification Of Proteins