Vitamins are access dietary factors that are they are provided to the body externally except Vitamin D. there are two types of vitamins-
- Fat-soluble Vitamins- Vitamin A, vitamin D, vitamin E, and vitamin K.
- Water-soluble Vitamins- Vitamin B(Complex) and vitamin C
Water-soluble vitamins are not normally stored to any extent in the body and the ingested vitamins in excess of requirement are excreted through the kidney. For normal body functions, water-soluble vitamins are very necessary. Most water-soluble vitamins are components of essential enzymes.
The important water-soluble vitamins include vitamin C and the vitamin B complex which include :
- Vitamin B1 (thiamin)
- Vitamin B2 (riboflavin)
- Vitamin B3 (niacin)
- Vitamin B5 (pantothenic acid)
- Vitamin B6 (pyridoxine)
- Vitamin B7 (biotin)
- Vitamin B9 (folic acid or folate)
- Vitamin B12 (cobalamin)
Vitamin C (Ascorbic Acid): –
Vitamin C, also known as ascorbic acid, is a water-soluble vitamin. Vitamin C is the antiscurvy vitamin. It favours the absorption of iron. It is destroyed by oxidation, especially at high temperatures, and is the vitamin most easily lost during food processing, storage, and cooking. Vitamin C-containing foods must be protected against exposure to oxygen to prevent losses.
On mild oxidation ascorbic acid is converted into dehydroascorbic acid. Both ascorbic acid and dehydroascorbic acid have vitamin C activity. When dehydroascorbic acid is treated with weak acid it is converted into diketogulonic acid (DKG) with no vitamin C activity and it can’t be reduced to dehydroascorbic acid again.
Functions of vitamin C
- vitamin C is necessary for the formation of the protein collagen, which is an important constituent of skin and connective tissue.
- It helps in the healing of wounds, fractures, bruises, and bleeding gums, and reduces liability to infections.
- Ascorbic acid is involved in the metabolism of some amino acids, such as tyrosine, in drug and folic acid metabolism.
- It is involved in the synthesis of epinephrine and anti-inflammatory steroids in the adrenal glands.
- Vitamin C together with vitamin E works as an antioxidant and plays a very significant role in neutralizing free radicals throughout the body.
- The absorption of iron is increased by dietary ascorbic acid.
- The enhancement of iron absorption takes place when the ascorbic acid content of the meal is 25-75 mg or more.
Sources of vitamin C
- Excellent sources of vitamin C are citrus fruits, berries, guava, capsicum, and green vegetables.
- Canned or frozen citrus fruits and tomatoes are also good sources of vitamin C.
- Milk, eggs, meat, and poultry contain little or no ascorbic acid.
Diseases due to lack of vitamin C
- When a person doesn’t take vitamin C for sufficient time then it develops scurvy. It results in the weakening of the collagenous structure, and this finally results in widespread capillary haemorrhaging.
- The lack of this also includes weakness, poor appetite and growth,
- Also, deficiency causes anaemia, tenderness to the touch, swollen and inflamed gums, loosening of teeth, and bone joint diseases.
Recommended Dietary Intake (RDI)
- For children, RDI is 45 mg/day.
- For adults, 60 mg/day for both men and women, 20 mg/day for pregnant women and 40 mg/day for lactating women are recommended.
Vitamin B-complex includes various vitamins. They are grouped because they are of the same nature. All of them are explained one by one below-
Vitamin B1 (Thiamin)
Thiamin was the first vitamin B that was recognized. It serves as a coenzyme in the body. Coenzymes are small compounds that help enzymes trigger chemical reactions that otherwise wouldn’t happen on their own.
Thiamin is readily soluble in water and insoluble in fat solvents. The dry vitamin is stable but solutions of it are unstable in the presence of heat or alkali. Temperature is a crucial factor in thiamin stability. Thermal destruction of this is pH-dependent.
It is important to note that the sensitivity of thiamin to sulphur dioxide, a common food preservative chemical, destroys vitamin activity and should not be used to preserve foods that are a major source of thiamin.
Functions of Thiamin-
- Thiamin is important as it works as a coenzyme. It combines with phosphoric acid to form TPP( thiamine pyrophosphate). It is important for the biological oxidation of glucose.
- Thiamin is necessary throughout life for the release of energy from fuel molecules.
- It plays role in muscle contraction and conduction of nerve signals.
Sources of vitamin B1
- The best source of thiamin is cereal grains, pulses and nuts.
- Other sources include liver, meats, egg yolk, fish etc.
Diseases due to deficiency of vitamin B1
Recommended Dietary Allowance
- For males 1.2-1.5 mg/day
- For females 1.0-1.2 mg/day.
Vitamin B2 (Riboflavin)
Vitamin B2 is named Riboflavin, part of the vitamin B-complex family. Riboflavin is orange and yellow in colour. On reduction, it changes into a colourless form. It is less soluble in water than thiamin but is more stable to heat in acid and neutral media. Its all activities get destroyed by heating in an alkaline solution.
On exposure to light, riboflavin readily loses its vitamin activity due to photochemical cleavage of the ribitol moiety of the vitamin, forming lumiflavin. That’s why milk is now sold in plastic or paper containers as when it was sold in glass bottles there is a 50-70% loss of riboflavin potency in two hours, due to direct sunlight.
Functions of Riboflavin
- It helps in the oxidative processes of living cells.
- It is necessary for cellular growth and tissue maintenance.
- Riboflavin helps in the production of corticosteroids, formation of RBCs, synthesis of glucose from non-carbohydrate materials and thyroid enzyme regulating activity.
Sources of Riboflavin
- Milk, cheese, liver eggs, and leafy vegetables.
- Dried yeast is also rich in vitamins.
- Pulses and lean meats are also good sources of riboflavin.
Diseases due to deficiency of the Vitamin B2
- Its deficiency causes reddened, denuded areas on the lips, with cracks at the corners of the mouth (cheilosis).
- Swollen and reddened tongue (glossitis).
- Its deficiency can also cause eye disorders such as itching, burning, dimness of vision and cataracts.
Recommended Dietary Intake
- 1.5-1.8 mg/day for men.
- 1.1-1.4 mg/day for women.
Vitamin B3 (Niacin)
Niacin is a vitamin which occurs in two forms nicotinic acid and nicotinamide. The main work of niacin in the human body is to form coenzymes that play an important role in biological oxidations. Its coenzymes are nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP).
These coenzymes are beneficial in releasing energy from carbohydrates, fats and proteins, and also participate in fat synthesis. Niacin is one of the stablest vitamins, being relatively resistant to heat, light, acids and alkalis.
Functions of Niacin
- Vitamin B3 helps in digestion and promotes a healthy appetite and glowing skin.
- It helps in protecting skin from sun damage. It is often used in cosmetics and creams used for anti-ageing.
- Niacin is used to treat anxiety, bipolar disorder, diarrhoea, cholera and depression etc.
- It helps in treating diabetes and high blood sugar levels. Most diabetic patients are able to effectively control HBA1C levels with help of niacin.
- It has anti-inflammatory properties which helps in reducing pain and provide relief in arthritis. It is also used in treatment of osteoarthritis.
Sources of Niacin
- Whole-grain cereals.
Diseases due to deficiency of niacin
- Deficiency of niacin results in weakness and indigestion.
- It can also cause ulcerated mouth and tongue.
- Prolonged deficiency leads to pellagra, and this results in dermatitis, diarrhoea and depression.
Recommended Dietary Intake
Niacin is measured in milligrams (mg) of niacin equivalents (NE). One NE equals 1 milligram of niacin or 60 mg of tryptophan.
- 16 mg NE for men
- 14 mg NE for women
- 18 mg NE for pregnant women and 17 mg NE for lactating women.
Vitamin B12 (cobalamin)
Vitamin B-12 is well known by the name cobalamin since it contains cobalt. It is very complex in nature. The cobalt present in the vitamin molecule occupies the centre of the molecule and may be attached to various chemical groups. When it is attached to the cyanide group the compound is called cyanocobalamin and when attached to the hydroxyl group, hydroxy cobalamin.
The former is the most stable form of the vitamin and is present in the body in very small amounts. Vitamin B-12 is present in animal protein foods. There is no vitamin B-12 in plant products such as grams, vegetables, and fruits. Strict vegetarians may not get sufficient vitamin B-12 from dietary sources. However, human requirements are very low and this is met by intestinal bacterial synthesis.
Functions of vitamin B-12
- It helps in synthesis of neurotransmitters and play a vital role in treatment of psychotic conditions like Alzheimer’s, memory loss and dementia.
- Cobalamin is necessary for normal functioning in the metabolism of all cells.
- Vitamin B-12 helps in binding the protein in the foods we eat.
- It is essentially needed to form red blood cells and DNA.
Sources of cobalamin
- Animal liver and kidneys
Diseases due to deficiency of vitamin B-12
- A long-term deficiency of vitamin B-12 results in an anaemia known as pernicious anaemia. The red blood cells enlarge but do not mature properly and the red cell count decreases. If anaemia is not treated, degenerative changes take place affecting the spinal cord, leading to sensory disturbances, general weakness and paralysis.
- Its deficiency causes gastritis which is inflammation of the stomach lining.
- Vitamin B-12 deficiency can lead to intestinal problems.
Recommended Dietary Intake
- For adults, the RDI is 2.4 mcg
- For lactating women is 2.8 mcg