What are vitamins? Functions of vitamins signs and symptoms of vitamins deficiencies


Vitamins are organic chemical compounds which cannot be synthesized in sufficient quantities by an organism and must be obtained from the diet as vital nutrients in limited amounts. They are essential for the normal growth and development of multicellular organisms. These vital nutrients facilitate the chemical reactions that produce among other things, skin, bones and muscles. Each vitamin has specific jobs in the body.  If there is serious deficiency in one or more of these vitamins, the body may develop a deficiency disease. Even minor deficiencies may cause critical medical problems and permanent damage. Once growth and development are completed, vitamins remain essential nutrients for the healthy maintenance of the cells, tissues and organs that make up a multicellular organism. They also enable a multicellular life that is formed to efficiently use chemical energy provided from food it eats to process the proteins, carbohydrates and fats required for respiration and other physiological functions.

The best way to get adequate vitamins is to eat a balanced diet from variety of foods. Vitamins are obtained from food, but a few are obtained from microorganisms and sunlight. For example, the intestinal or gut flora produces vitamin K and biotin while vitamin D is synthesized in the skin through the natural ultraviolet wavelength of sunlight. In some cases, people may need to take a daily multivitamin produced as commodity chemicals for optimal health. However, high doses of some vitamins can cause sickness. How much of each vitamin that people need depends on such as age, health status, pregnancy and gender.


Vitamins are group of substances that the body needs in small amounts for normal growth and development. They are substances that are essential for ideal function, growth and development of body cells, tissues and organs. Thirteen vitamins are universally recognized presently. They are divided into fat and water soluble vitamins. Fat-soluble vitamins are stored in the body’s fatty tissues. The four fat-soluble vitamins are vitamins A, D, E and K. There are nine water-soluble (eight vitamin Bs and vitamin C) vitamins. The body must use water-soluble vitamins right away. Any leftover water-soluble vitamins are excreted by the body through the urine except vitamin B12 which can be stored in the liver for many years.


Vitamins are classified by their diverse biochemical functions. Each vitamin is typically used in multiple reactions; therefore, most have multiple functions.  Some have hormone-like functions as regulators of mineral metabolism (example vitamin D) or regulators of cell; and tissue growth and differentiation (such as some forms of vitamin A). Others function as antioxidants (example vitamin E and vitamin C). The largest number of vitamins (such as B complex vitamins) function as precursors for enzyme cofactors that help enzymes in their work as catalysts in metabolism.

Vitamin A helps to form and maintain growth of healthy teeth, bones, soft tissues, mucus membranes and skin; and it is good for vision maintenance in dim light.

Vitamin B complex serves as coenzymes for metabolism and for tissue respiration. It helps to produce red blood cells and maintain brain, heart and central nervous system functions.  It helps to maintain healthy skin and nerves. It also has cholesterol-lowering effects. Vitamin B complex helps the body cells to change carbohydrates into energy for body maintenance especially during pregnancy and breast-feeding.

Vitamin C is a useful antioxidant and it is essential for maintaining healthy connective tissues and cell wall integrity; and synthesis of collagen. It promotes wound healing, healthy teeth and gums. It helps the body to absorb iron which is relevant for body functions.

Vitamin D helps in the absorption of phosphorus and calcium from the intestine and their deposition inside bones for healthy teeth and bones. It also helps to maintain proper blood levels of calcium and phosphorus which are essential elements for metabolism.

Vitamin E is a good antioxidant. It stabilizes cell membranes and reduces coronary thrombosis in heart diseases. It plays a role in the formation of red blood cells and helps the body use vitamin K. Vitamin K is a blood clotting factor and is important for promoting healthy bone.



Lack of adequate quantities of any of the vitamins in diet causes specific vitamin deficiency diseases or health problems or abnormalities. The following signs and symptoms are associated with vitamins deficiencies. They include stunted growth, night blindness, xerophthalmia -progressive nutritional disorder that cause cornea and conjunctiva to be dry, wrinkled and thickened due lack of vitamin A. Other signs and symptoms of vitamin A deficiency are blindness, pernicious anemia, keratomalacia- serious eye disease that softens and perforates the cornea and makes blindness inevitable.

Beriberi-nutritional disorder that can cause edema, emaciation, nerve degeneration and death from heart failure is due to lack of vitamin B complex.  Also, Pellagra-a disease that causes scaly dermatitis, diarrhea and depression are signs and symptoms of vitamin B complex deficiency.

Scurvy – a disorder that can cause swollen bleeding gum, fatigue and hemorrhage are signs and symptoms of vitamin C deficiency. Rickets- childhood disorder affecting calcium and phosphorus metabolism, causing bone softness and malformation; and poor wound healing are signs and symptoms of vitamin D deficiency. Also, nervous system degeneration, bones decalcification that may cause severe pain and osteomalacia-softening of bones are caused by lack of vitamin D.

The major signs and symptoms of lack of vitamin E are diffuse muscle weakness, muscle mass loss, limited upward gaze or abnormal eye movement, unstable walking, vision challenges and poor nerve impulse transmission. There may be greasy stool, chronic diarrhea, anemia and bile secretion problem.

The deficiency of vitamin K can show signs and symptoms of bruising easily, nose or gum oozing, excessive bleeding (from such as punctures, wounds, intestinal tract, injection or surgery sites), blood in urine and/or stool, heavy periods and high prothrombin time.


Essentially, Vitamins are obtained from food, microorganisms and sunlight. Dark colored fruits, dark leafy vegetables, egg yolk, fortified milk and dairy products (cheese, yogurt, butter and cream), liver, beef, fish, cod liver oil, cabbage, lettuce and carrots supply vitamin A. Vitamin B complex are got from rice bran, egg, liver, beans, nuts, avocado, enriched breads and fortified cereals. Other sources of Vitamin B complex are fish (tuna and salt-water fish), organ and lean meats, banana, legumes, poultry, potatoes, whole grains, animals and dairy products.

Broccoli, Brussels sprouts, cabbage, cauliflower, spinach, strawberries, tomato juice, tomatoes, most fresh fruits like mangoes and oranges; vegetables and potatoes are rich in vitamin C. Vitamin D can be sourced from fish (fatty fish such as salmon, mackerel and herring); fish liver oils (cod’s liver oil) and fortified cereals. Fortified foods such as soymilk, fortified milk and dairy products (cheese, yogurt, butter and cream), and sunlight are also good sources of vitamin D.

Vitamin E is a vital nutrient from eggs, whole meal cereals, wheat germ oil, unrefined vegetable oils and avocado. Also, dark green vegetables (spinach, broccoli, asparagus, turnip greens); oils and margarine (made from safflower, corn and sunflower oils), papaya, mango, seeds, nuts and wheat germ are providers of Vitamin E.

Vitamin K comes from cabbage, cauliflower, cereals and dark green vegetables (broccoli, Brussels sprouts and asparagus). Other providers of vitamin K are dark leafy vegetables (spinach, kale, collards and turnip greens), fish, liver, beef, eggs and meat. It is important to note that the best ways to get adequate vitamins and prevent or treat their deficiencies are to get adequate exposures and eat balanced diet from the various vitamin sources above.

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