The human body requires two types of nutrients for its proper functioning- one is macronutrients and the other is micronutrients.
Vitamins come under the category of micronutrients. The organic compounds which are required in very small amounts to lead a healthy life are known as vitamins.
Mostly, vitamins are acquired from food because the human body produces some vitamins in very little amount and some vitamins are not produced by the human body at all. Since vitamins are necessary for the proper functioning of the body so their need depends upon the metabolic activities of an individual as their daily requirements are not fixed but many factors like physical activity, age group, pregnancy, and special nutritional requirements are considered in evaluating the role of vitamins in maintaining a healthy body.
Types of vitamins
Two general classes of vitamins are there- Fat soluble and Water soluble vitamins. There are total 13 recognized vitamins from both categories. The vitamins of known category include vitamin A, C, D, E, and K, and the B vitamins: thiamine (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), cyanocobalamin (B12), biotin, and folate/folic acid.
Fat – soluble vitamins
The fat-soluble vitamins are stored in the liver and fatty cells of the body. These vitamins are absorbed into the body through intestinal tract and are soluble in fatty acids and lipids. These types of vitamins do not need to be taken as often because they are stored in the body for longer times and are not easily excreted. Fat-soluble vitamins include vitamins A, D, E, and K.
These types of vitamins are readily soluble in water and due to this reason, they can travel freely in the blood. The excess amount of these vitamins are excreted from the body through the kidneys. Water-soluble vitamins are required frequently. Water-soluble vitamins include thiamine (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), cyanocobalamin (B12), biotin, and folate/folic acid.
Sources and function of vitamins
Vitamin A is present in the body in its precursor form which is beta-carotene. Retinol or retinal are their chemical names. Sources of vitamin A include green leafy vegetables, germination cereals, and pulses, fortified milk, cheese, cream, butter, fortified margarine, meat, fish, green mango, papaya, pumpkin, yellow fruits, and vegetables. Other sources are eggs, spinach, cabbage, carrots, amaranth, angel liver oils, cod liver oil, liver, or halibut liver oil.
Vitamin A is needed in the proper functioning of the eye, especially vision. It is also required for healthy skin and the growth of bones and teeth also depends upon vitamin A present in the body. It also helps in making the immune system strong. Vitamin A deficiency causes night blindness, keratomalacia, weak immune system, etc.
The purpose of this vitamin is to control the absorption of calcium and phosphorous in the body. Ergocalciferol and cholecalciferol are its chemical names. Sources of vitamin D include egg yolks, liver, fatty fish, fortified milk and fortified margarine. When exposed to sunlight, the skin can make vitamin D. This vitamin also has antioxidant properties. The deficiency of vitamin D causes impaired bone development, rickets in children and osteomalacia in adults.
Vitamin E is a natural antioxidant and ant- sterility factor. Tocopherols or tocotrienols are the chemical names to which it is structurally related. Sources of vitamin E include Polyunsaturated plant oils (soybean, corn, cottonseed, safflower), leafy green vegetables; wheat germ, whole-grain products, liver; egg yolks; nuts, and seeds. The deficiency of vitamin E is not common, but when it occurs it is associated in humans with cystic fibro-sis, hemolytic anemia in newborns, ataxia, and abetalipoproteinemia.
The main purpose of this vitamin is the synthesis of prothrombin in the liver in co- relation with other vitamin K affected clotting factors i. e. VII, IX, X, protein C and S which are essential for normal blood coagulation or blood clotting.
Sources of vitamin E include leafy green vegetables such as kale, collard greens, and spinach; green vegetables such as broccoli, Brussels sprouts, and asparagus.
It is also produced in the intestinal tract by bacteria. This vitamin is very important as it is required for proper and timely blood clotting in order to avoid loss of blood during any injury. The deficiency of vitamin K causes prolonged bleeding and longer clotting time in adults and hemorrhagic diseases in babies.
It is a part of an enzyme needed for energy metabolism and also important for nerve function. It is also known as thiamine. this is found in all nutritious foods in moderate amounts like pork, whole grain foods or enriched bread and cereals, sunflower seeds, brown rice, whole-grain rye, asparagus, kale, cauliflower, potatoes, oranges, liver, and eggs. legumes, nuts, and seeds.
The deficiency causes beriberi, polyneuritis, mental disarray, ataxia, and Wernicke-Korsakoff syndrome in alcoholics. Excess can lead to tachycardia, migraines or peevishness, a sleeping disorder
It is a part of an enzyme needed for energy metabolism and also important for normal vision and skin health. this is also known as riboflavin. It is mainly found in milk and milk products; leafy green vegetables; whole-grain foods, asparagus, bananas, persimmons, okra, chard, cottage cheese, milk, yogurt, meat, eggs, fish, and green beans enriched bread and cereals.
Its deficiency can cause ariboflavinosis.
It comes under the category of water-soluble vitamin and is also important for the nervous system, digestive system, and skin health. Chemically, it is known as niacin.
Good sources can include meat, poultry, fish, whole-grain foods, enriched bread and cereals, vegetables (especially mushrooms, asparagus, and leafy green vegetables), peanut butter.
Its deficiency can cause pellagra along with diarrhea, dermatitis, and mental disturbance.
This vitamin is involved in hormonogenesis and energy production. It is also known as pantothenic acid. Sources of this vitamin are meats, whole-grains (milling may remove it), broccoli, avocados, royal jelly, and fish ovaries and its deficiency can lead to paresthesia.
It is a part of an enzyme needed for protein metabolism and also helps in the formation of red blood cells. It is known as pyridoxine. Good sources are meat, fish, poultry, vegetables, fruits. Its deficiency causes anemia, peripheral neuropathy, or damage to parts of the nervous system.
It is known as biotin and is helpful in metabolism. It is mainly found in green beans, egg yolk, dark green vegetables, kidneys, and liver and its deficiency can cause dermatitis or enteritis, or inflammation of the intestine.
It is also known as folic acid and is part of an enzyme needed for making DNA and new cells, especially red blood cells. Its main sources include leafy green vegetables and legumes, seeds, orange juice, and liver.
Its deficiency causes cell defects and also affects cell proliferation.
This vitamin is also known as ascorbic acid and is involved in protein metabolism, important for immune system health, and also aids in iron absorption. It also acts as an antioxidant.
The main sources of these vitamins are citrus fruits, vegetables, papayas, mangoes, kiwifruit. Its deficiency causes scurvy along with muscle pain, joint swelling, and bleeding.