Vitamins: Types, Functions, Food Sources, Deficiencies

Our body needs about forty known elements that are essential for its nutrition. Of these, thirteen are vitamins, fifteen are essential minerals, trace minerals, and electrolytes, and twelve are amino acids.

Vitamins were discovered in the late nineteen century when researchers began to research certain foods that were known for centuries to prevent diseases; examples being oranges for scurvy and unpolished rice for beriberi.

Scurvy is caused by a vitamin C deficiency, beriberi is caused by vitamin B1 deficiency and pellagra is caused by vitamin B3 deficiency.

What are vitamins?

Vitamins are organic compounds containing a combination of several chemical elements. They are made by plants with the help of sunlight and by the gut’s bacterial flora in our body. Most of our body’s vitamins come from plants.

Most of the vitamins that come from animal foods such as eggs are by-products from the plants eaten by the animals or were made by the gut flora.

There are three criteria by which a substance can be defined as a vitamin:

1. A vitamin is a nutrient that our body requires in small quantities for proper body function.
2. It must be an organic compound.
3. A deficiency of vitamins can lead to a set of symptoms or diseases that can be corrected by taking the required amount of the vitamin.

Types

Vitamins are classified into two types:

1. Fat-soluble vitamins
2. Water-soluble vitamins

Fat-soluble vitamins

The major fat-soluble vitamins are vitamins A, D, E, and K. They are found in foods containing fats and do not dissolve in water.

They are oily in consistency and require the presence of bile acids in the intestine to be absorbed into the blood. The bile acids act as emulsifying agents.

Once absorbed they are taken to fat-storage sites in the body. When required, lipoproteins transport them through the blood to wherever they are required.

Water-soluble vitamins

These vitamins are readily absorbed directly into the bloodstream and do not require any intermediary agent to help in their absorption.

Once absorbed, they circulate freely in the body fluids and make themselves available wherever and whenever they are needed.

The water-soluble vitamins are not stored in large quantities as fat-soluble vitamins are and they are stored for a short time only. Once a saturation level is reached, most of the excess of these vitamins is removed from the body through urine.

Vitamins B and C are water-soluble vitamins. The vitamin B complex includes: Thiamin (B1), Riboflavin (B2), Niacin (B3), Pantothenic acid (B5), Pyridoxine (B6), Folic acid (B9), and Cobalamin (B12)

Main functions

Vitamins, along with minerals, are essential nutrients in the body. They are an essential part of the complex machine, which our body is. Each vitamin fits into a different part of our body and makes it function to the optimum.

Chemically, you could call vitamins, catalysts. A catalyst is an agent that facilitates a chemical reaction without being part of the reaction.

Functions of water-soluble vitamins

The following functions in the body are attributed to water-soluble vitamins:

• Thiamine (vitamin B1) acts as a catalyst in a series of chemical reactions that metabolize carbohydrates (sugars) and provide enough energy for various body functions. It regulates the functioning of the nervous system, heart, and brain, maintains good eyesight, and boosts immunity.
• Riboflavin (vitamin B2) facilitates a series of chemical reactions that release energy from proteins and carbohydrates. Therefore your daily riboflavin requirement depends on the energy you use in a day. It’s important for red blood cell production and also exhibits antioxidant properties thereby improving your immunity.
• Niacin (vitamin B3) acts as a coenzyme and facilitates many enzymatic reactions. It converts nutrients into energy, plays an important role in the production of cholesterol and fats, helps in the creation and repair of DNA, and has antioxidant effects.
• Pantothenic acid (vitamin B5) helps in the metabolism of fats and carbohydrates for generating energy. Its role is critical in the manufacture of red blood cells, as well as sex and stress-linked hormones.
• Pyridoxine (vitamin B6) helps in the metabolism process, turns nutrients into energy, and helps to create neurotransmitters, such as serotonin and dopamine.
• Biotin (vitamin B7) helps to metabolize carbohydrates, fats, and amino acids and helps to strengthen hair and nails.
• Folic acid (vitamin B9) promotes normal cell division and replaces old worn-out cells with new ones. It helps in the production of red blood cells and DNA, the building block of the human body, which carries your genetic characteristics.
• Cobalamin (vitamin B12) also helps in the production of red blood cells and DNA and plays a key role in the development and function of the brain and nerves.
• Ascorbic acid (vitamin C) is an important faction of the immune system. It helps to protect cells, maintains healthy skin, blood vessels, bones, and cartilage, and helps with the healing of wounds.

Functions of fat-soluble vitamins

• Vitamin A is important for vision, cell division, reproduction, and immunity. It also has antioxidant properties.
• Vitamin D helps form strong bones and teeth and prevents osteoporosis. It improves body resistance and reduces inflammation.
• Vitamin E is a powerful antioxidant helping to build a strong immune system. It helps in the production of red blood cells and plays a key role in the production of prostaglandins, which are required for regulating blood pressure and muscle contraction.
• Vitamin K produces prothrombin, a protein that is important for the clotting of blood, the metabolism of bone, and the health of the heart. Vitamin K also helps generate energy production in the mitochondria of cells.

Sources of Vitamins

Listed below are the different types of vitamins along with their sources.

The best sources of fat-soluble vitamins include:

• Vitamin A: Potato, carrots, pumpkins, spinach, beef, and eggs
• Vitamin D: Fortified milk and other dairy products
• Vitamin E: Fortified cereals, leafy green vegetables, seeds, and nuts
• Vitamin K: Dark green leafy vegetables and in turnip or beet green

The best sources of water-soluble vitamins include:

• Vitamin C: Abundantly in all citrus fruits such as oranges and grapefruits
• Vitamin B1 or Thiamin: Pork chops, ham, enriched grains, and seeds
• Vitamin B2 or Riboflavin: Whole grains, enriched grains, and dairy products
• Vitamin B3 or Niacin: Whole grains, mushrooms, fish, and poultry
• Vitamin B5 or Pantothenic Acid: Whole grains, chicken, broccoli, legumes
• Vitamin B6 or Pyridoxine: Fortified cereals and soy products
• Vitamin B7 or Biotin: Organ meats, fish, meat, eggs, seeds, nuts, and certain vegetables (such as sweet potatoes)
• Vitamin B9 or Folic Acid: Leafy vegetables
• Vitamin B12: Fish, poultry, meat, and dairy products

Effects of vitamin deficiencies

A deficiency of vitamins (long-term lack of vitamins) in the body can lead to certain diseases and health conditions.