A vitamin is an organic compound (or molecule) or micronutrient which is required for development and healthy life. It is essential, noncaloric nutrients that are required in the diet in only small amounts to maintain normal body functions such as maintenance, growth, metabolism, and production.
Vitamins are essential for life and growth. The chemical structure of each vitamin is specific. Some of them have a simple structure like vitamin C whereas other such as vitamin D has a complex structure.
Vitamins do not provide calories but are essential for metabolic reactions in the body that release energy from carbohydrates, proteins, and fats.
Vitamins act as a biological regulator and metabolic regulatory. Every vitamin has its own functions in the body. It is also called life element. Therefore, we cannot substitute one vitamin for another in the body.
Most of the vitamin are formed by plants with the help of sunlight. Vitamins cannot be synthesized in the body except vitamin D and vitamin K that are synthesized by the body itself.
Therefore, these vitamins are required to take in the diet. Lack of these vitamins is produced illness in the body if you do not take an insufficient amount in the diet. There are about 30 different types of vitamins described so far.
Types/Classification of Vitamins
Naturally, vitamins have been divided into two groups based on solubility. They are fat-soluble and water-soluble vitamins.
1. Fat-soluble vitamins:
Fat-soluble vitamins are those vitamins that can only be absorbed in the presence of fats. There are four types of fat-soluble vitamins. They are:
- Vitamin A
- Vitamin D
- Vitamin E
- Vitamin K
These vitamins are found in fats and oils of food. Therefore, the presence of some good fats in the diet is essential for their absorption.
Once absorbed, these vitamins are stored in fatty tissues and liver for a long period of time until the body needs them. This is because you do not need them every day and the body can use these vitamin stores for future use. You do not need to eat foods containing these fat-soluble vitamins every day.
Fat soluble vitamins do not dissolve in water (H2O) but dissolve in fat. If these are taken in excess, they cause a condition of toxicity and adverse reaction. Each of the fat-soluble vitamins has multiple functions in the body.
2. Water-soluble vitamins:
Water-soluble vitamins are those vitamins that consist of a large number of substances. They must be consumed frequently in daily diet. Vitamin C and B-complex vitamins are called water-soluble vitamins because they are easily dissolved in water.
- B Vitamins
- Thiamin (B1)
- Riboflavin (B2)
- Niacin (B3)
- Pantothenic Acid (B5)
- Pyridoxine (B6)
- Cyanocobalamin (B12)
- Biotin
- Folic Acid
- Vitamin C
Water-soluble vitamins easily dissolve in the food and some of them are partly lost in the cooking process. That is, they are easily destroyed during food preparation and processing.
These vitamins are easily absorbed directly into the blood stream. Once absorbed, they circulate in the body and are available when needed for body function.
Most of the water-soluble vitamins are not stored in large amounts for a long period of time. If water-soluble vitamins are the excess amount in the body, they have washed away from the body via urine.
Let’s understand the functions and sources of each vitamin in brief.
1. Vitamin A (Retinol)
Vitamin A also called retinol, was discovered by Mc Collum and Davis but was isolated by Holmes. It is also known as an anti-infection. It can be synthesized in the liver from yellow and red carotenoid pigments.
Vitamin-A can be found in fruits, vegetables, eggs, milk, butter, meat, and fish.
Role and Functions:
- Required for the maintenance of normal night vision.
- Helps in maintaining healthy immune system.
- Repairing and growing skin, hair, nail, and cornea of the eye.
- Development of sperm and organs.
- Involves in the formation and maintenance of the teeth, bones, tissues, white blood cells, and the immune system.
- Maintains normal, living secretory epithelia in mucous membranes and glands.
Sources:
- Chicken liver, fish oil, cheese, milk, egg yolk,
- Carrot juice, green vegetable, ghee, butter,
- Tomatoes, papaya, guava, orange, sweet potato, mango, etc.
Recommended Daily Intake:
The recommended daily requirement of vitamin A is 900 micrograms (mcg) for adult men, 700 mcg for women, 770 mcg for during pregnancy, and 1300 mcg during breastfeeding.
Deficiency:
Deficiency of vitamin A causes diseases like Night blindness, Dry eyes(Xerophthalmia), Dry and itchy skin, and Diarrhea.
2. Vitamin D (Calciferol)
Vitamin D is also known as sunshine or antiricket. It is an essential nutrient which you can get in the body when your skin is exposed to the sunlight for a certain period of time.
Otherwise, you will have to take an essential amount from the foods. It has two major forms vitamin D2 and vitamin D3.
Vitamin D is synthesized in the skin by cholesterol and UV light. It regulates the absorption and utilization of calcium and phosphorus.
Role and Functions:
- Regulation of the calcium and phosphorus levels in the blood by promoting their absorption from food in the intestine, and by promoting re-absorption of calcium in the kidney.
- Formation of bones and teeth.
- Essential in the development of the strong skeleton.
- Maintaining muscle strength and normal glucose level.
Sources:
- Meat, liver, milk, cod liver oil, and shark liver oil, fish, egg yolk, Mushroom, etc.
Recommended Daily Intake:
- The recommended daily requirement of vitamin D for adults between 19 to 50 years is 15 micrograms (mcg) per day, for 71+ years 20 mcg per day, 15 mcg per day for during pregnancy, and breastfeeding woman.
Deficiency:
- Deficiency of vitamin D causes diseases like poor mineralization of bones causing rickets in children, osteomalacia (soft bones), and if the calcium is also deficient in adults, osteoporosis may be.
3. Vitamin E (Tocopherols or Tocotrienol)
Vitamin E is commonly called anti sterility or beauty vitamin. It inhibits peroxide formation and thereby prevents the damage of membrane lipids.
Role and Functions:
- Removes scars and wrinkles of the skin.
- Acts as an antioxidant in the human body.
Sources:
- Wheat, sunflower seeds, almonds, peanuts,
- Vegetable oils, dark leafy vegetables, sweet potato, pumpkin, oily fish, etc.
Recommended Daily Intake:
- The recommended daily requirement of vitamin D for adults and a pregnant woman is 15 mg per day, and during breastfeeding women, 19 mg per day.
Deficiency:
- Diseases are sterility (impotence) and muscular atrophy.
4. Vitamin K (Phylloquinone)
Vitamin K is commonly called antihemorrhagic. It is synthesized by bacteria in the colon. It was discovered by Danish Scientist Dam in 1935.
Role and Functions:
- Normal clotting of blood.
- Increasing the strength of bone.
- Essential for the synthesis of prothrombin in the liver.
Sources:
- Green plants, green cabbage, cauliflower,
- Spinach, nuts, fruits, vegetable oils, etc.
Recommended Daily Intake:
The recommended daily requirement for adult men is 120 mcg per day and for women (during pregnancy and breastfeeding) is 90 mcg per day.
Deficiency:
- It causes uncontrolled bleeding (no coagulation or clotting).
In this tutorial, you have learned about what is vitamin and its types: fat-soluble vitamins and water-soluble vitamins. Hope that you will have understood the basic points of roles, functions, sources, recommended daily intake, and deficiency of each vitamin. In the next tutorial, we will understand water-soluble vitamins and their roles, functions, sources, etc.