Vitamins: Types of Vitamins, Functioning and Sources


Vitamins are organic compounds or substances that plays essential role in body functioning and growth. Body organism requires them in very small quantity for healthy growth and development by our body. 

They are essential nutrients to our body are either at all or not in sufficient quantities. Thus they synthesized by organism so they are necessary to include in our daily food intake.

Why we need vitamins?

  • For the normal body functioning, good health and to prevent or cure any disease, vitamins are necessary.
  • Vitamins are essential micronutrient that are needed for proper metabolism functioning.
  • Also, it helps you in proper formation of blood cells and hormones.
  • Vitamins repair cellular damage, convert food into energy and heal wounds.
  • Sufficient quantity of vitamins gives you strong bones and healthy teeth.
  • Pregnancy helps such as spinal and brain defect in early pregnancy.

Different organisms have different vitamin requirements. For example, humans need to consume vitamin C (ascorbic acid) while most animal don’t, as they can produce enough vitamin C. People get vitamin D from sunlight as it’s not available in required quantity in food.

Every vitamin has its own role and required in different quantity in our body. Lack of vitamins in sufficient quantity can cause you certain vitamin specific deficiency.

On other side, taking too much of vitamins leads you some other problems. Like, too much of vitamin C can cause diarrhea or stomach cramps.

Types of Vitamins

There are 13 vitamins your body requires, either water-soluble or fat-soluble. Due to the carbon content, vitamins are described as organic compounds. Both, water-soluble and fat-soluble vitamins absorbed differently in our body.

Water soluble vitamins and fat soluble vitamins

Water soluble vitamins are the vitamins that easily dissolves in water and immediately absorbed into tissues for use. Excess intake of water-soluble vitamins are quickly excreted from the body as urine.

Unlike fat-soluble vitamins, they are not readily stored in body, so regular intake of them is important.

As water-soluble vitamins are quickly discharged through urine, their excess amount hardly accumulate to toxic levels. Type of this vitamins are all B vitamins and Vitamin C.

Fat soluble vitamins are the vitamins that easily stored in body cells and their consumption is not often as water-soluble vitamins. As the name suggests, they dissolves in fat.

Rather than extracting from body, excess fat-soluble vitamins stored in fatty tissues and liver of our body for future use. Fat-soluble vitamins absorbed by fat globules that travel along the intestines and distributed through body in bloodstream.

As they are not quickly excreted, their excess intake can increase toxic levels. Type of fat-soluble vitamins are vitamin A, vitamin D, vitamin E and vitamin K.

Let me give you review of all vitamins, their basic functions, deficiency and sources:

1. Vitamin A

Vitamin A is a member of fat-soluble vitamins that includes retinol, retinal, retinoic acid and several provitamin A carotenoids, especially beta-carotene.

What does vitamin A do
  • It is required for good immune system and vision as it helps to produce white blood cells to fight infection.
  • You require Vitamin A for cell reproduction, healthy skin, tissues and mucous membranes.
  • Important for proper growth of bones and teeth. Protect against cataracts, lower lung cancer risk.
Vitamin A deficiency symptoms

Vitamin A deficiency includes:

  • night-blindness with poor eye health
  • dry cornea
  • Skin dryness and damage
  • trouble in having pregnancy or miscarriages
  • high chances of infections
  • growth retardation
  • And poor healing process
Sources of Vitamin A

Green leafy vegetable, carrots, sweet potatoes, pumpkin, broccoli, spinach, eggs, milk, liver, butter, cheese

2. Vitamin B

Vitamin B are the water-soluble vitamins are important in cell metabolism. Vitamin B are classified by specific name of each vitamin as B1 (thiamine), B2 (riboflavin), B3 (niacin or nicotinic acid), B5 (pantothenic acid), B6 (pyridoxine), B7 (biotin), B9 (folic acid), B12 (cyanocobalamin).

What does vitamin B complex do
  • Vitamin B complex helps to convert food to energy and is essential for healthy skin and nervous system.
  • Promotes production of red blood cells and body growth.
  • Helps to maintain skin and hair health. For healthy muscles as well as reduce the risk of heart diseases.
  • Release of energy from carbohydrates.
  • Essential for normal cell division, especially during pregnancy and infancy, production of blood cells in bone marrow.
  • Required for metabolism of lipids, proteins and carbohydrates. Helps to produce hormones, hemoglobin and DNA.
Vitamin B deficiency symptoms


  • beriberi
  • nervous system
  • anemia
  • weight loss
  • emotional disturbance
  • pain and weakness in limbs
  • irregular heartbeat
  • body tissues swelling
  • Skin, tongue and lips inflammation, sore throat
  • Mental confusion and weakness
  • diarrhea
  • aggression
  • insomnia in case of pellagra.
  • Acne
  • paresthesia
  • impaired growth and neurological disorders
  • birth defects
  • impaired red blood cells formation
  • mouth inflammation
Sources of Vitamin B

Potatoes, oranges, kale, cauliflower, eggs, sunflower seeds, liver, bananas, milk, yogurt, avocados, nuts, whole-grains, fish, legumes, broccoli, leafy vegetables, cereals and soy products.

Note:  All the symptoms, functioning and sources are common for all Vitamin B Types.

3. Vitamin C

Vitamin C is a water-soluble vitamin and also known as ascorbic acid.

What does vitamin C do
  • Important in wound healing and tissue repair.
  • Acts as antioxidant and is important for immune system.
  • Helps in healing wounds and absorption of iron in body.
  • Essential for several enzymes functioning. Also protects you from cancer, stroke and cardiovascular.
Vitamin C deficiency symptoms
  • Anemia
  • swollen and bleeding gums
  • bleeding from mucous membranes
  • brown spots on skin
  • joint pain
  • slow wound healing

High intake can causes:

Sources of Vitamin C

Kiwi, broccoli, citrus fruits, strawberries, bell peppers, tomatoes, Brussels sprouts, lemon juice, potatoes, cabbage, spinach.

4. Vitamin D

It’s a fat-soluble vitamin that contains compounds vitamin D3 (cholecalciferol) and vitamin D2 (ergocalciferol) in humans. As vitamin D is in very less amount in foods, its main source is sun exposure.

What does vitamin D do
  • Essential for healthy bones and teeth by absorbing calcium, magnesium and phosphate.
Vitamin D deficiency symptoms

Rickets, in which child is having weak, soft and deformed bones and teeth. Osteoporosis, in which adults are suffering from soften bones that leads to increased risk of fractures, spine bend, bowing legs.

Sources of Vitamin D

Major source of vitamin D is sunlight. Others are mushrooms, eggs, fortified milk, fatty fish, and fortified cereals.

5. Vitamin E

Vitamin E is a fat-soluble vitamin that also called as tocopherols or tocotrienols.

What does vitamin E do
  • Vitamin E acts as antioxidant; protecting cell membranes or cell walls.
  • Prevent free radicals from damaging body cells.
Vitamin E deficiency symptoms

Hardly seen due to dietary fat digesting problem. Nerve problems, ataxia, worsening immune system, peripheral neuropathy and destroying red blood cells.

Sources of Vitamin E

Almonds, eggs, avocado, kiwi, nuts, green vegetables, wheat germ, olives, Polyunsaturated oils (sunflower, corn, safflower), whole grains.

6. Vitamin K

Just like Vitamins A, D and E, vitamin K (in German, K is from Koagulation) is also fat-soluble vitamin. Vitamin K contains two natural vitamers named vitamin K1 (phylloquinone) and Vitamin K2 (menaquinone).

What does vitamin E do
  • Requires for synthesis of certain proteins that are essential for blood clotting.
  • Helpful in bone formation and heal bone disease like osteoporosis.
Vitamin K deficiency symptoms

Newborns are at high risk of this deficiency. Bleeding disorders, includes symptoms like nose bleeding, heavy menstrual bleeding, bleeding of gums. Others can be lesions easily, blood clots, osteoporosis and anemia.

Sources of Vitamin K

Vitamin K1 is directly available from plants due to photosynthesis process and found in good amount in green vegetables. It is converted in to vitamin K2 by bacteria. Sources includes, kale, spinach, Swiss chard, broccoli, collards, Brussels sprouts, cabbage, parsley, asparagus, liver, eggs and milk.

“Neither less nor more amount of vitamins are essential for our body to function each and every organ perfectly. Take your vitamins, for vitamins to take care of you!”

Zalak Thakkar