VITAMIN B COMPLEX
Vitamin B complex includes several water soluble vitamins. Although the members of vitamin B-complex differ chemically, they are placed in the same group because they all act as coenzymes and their actions are closely related. The vitamins of B-complex groups are as follows:
This was the first discovered member of vitamin B group and called as Vitamin B1. It is clinically called aneurin or anti-beriberi vitamin because it prevents neuritis and beriberi.
The plant sources are seeds of pea, beans and soyabean, nuts and cereals like rice, wheat etc., Actually the outer coatings of the above mentioned materials are rich in this vitamin. For this reason, whole wheat flour and unpolished rice having the reddish brown outer coating are good sources of vitamin B1. Yeast is a very good source of it. Carrot, beet, onion, cauliflower, turnip, orange etc., also contain this vitamin. Among the animal sources, the most important ones are meat, liver, eggs.
Thiamine as one of the water soluble vitamins acts as a coenzyme in the form of thiamine pyrophosphate (TPP) and it takes part in (i) the oxidative decarboxylation reactions
catalysed by the enzymes pyruvic dehydrogenase and cc-ketoglutaric dehydrogenase of TCA cycle, and (ii) transketolase reaction of pentose phosphate pathway (PPP). Thus, it is apparent that thiamine is involved in carbohydrate metabolism and energy production. It also helps in nerve impulse transmission.
Deficiency of vitamin BI leads to a disease called beriberi and weakness of nerves and muscles. Prolonged deficiency may be caused paralysis of limbs, blindness and deafness. In extreme cases, death may occur due to cardio-respiratory failure.
Riboflavin as one of the water soluble vitamins ands is commonly known as vitamin B2. It is a ribose sugar containing flavin compound.
Riboflavin is found in most of the natural foodstuffs. Yeast, germinated seeds and leafy vegetables are good plant sources. Important animal sources include liver, meat, fish, egg and milk.
It acts as coenzyme of the enzymes called flavoproteins. The flavoproteins are oxido-reductases that tale part in cellular respiration. Vitamin B2 helps in general growth of the body and proper maintenance of health and functioning of ectodermal tissues like skin and oral mucosa.
I general, deficiency of riboflavin alone do not occur because this vitamin is present in most natural foodstuffs. Often it is associated with deficiency of other vitamins. Riboflavin deficiency can be experimentally produced by feeding artificially prepared riboflavin free diet. Seborrheic dermatitis, Cheilosis, Glossitis and Corneal vascularisation, with itching eyes and photophobia may be the deficiency symptom of Vitamin B2.
NIACIN OR NICOTINIC ACID
This is another of the water soluble vitamins was originally known as pellagra preventing vitamin or P-P factor in short. Chemically, it was isolated as nicotinic acid, and its active form an amide was called nicotinamide.
It is found in many plant and animal products. Among the plant sources, it is abundant in yeast, legumes, peanuts and outer coat of cereals. Important animal sources are liver, meat, fish etc.
It acts for oxidation of fatty acids, synthesis of fatty acids and cholesterol, and many other important metabolic pathways.
In man, deficiency of niacin produces the disease called pellagra with the symptom of Dermatitis with red, itchy, dry, thickened, pigmented and desquamated skin, Glossitis with red, swollen and inflammated tongue, Diarrhea with anorexia, vomiting and loss of weight and Dementia with irritability, anxiety and mental fatigue.
It is also one of the water soluble vitamins and is now commonly known as vitamin B6. It is active in two forms—Pyridoxal phosphate and pyridoxamine phosphate. Since this vitamin occurs in nature in the three above mentioned forms i.e., pyridoxine, pyridoxal phosphate and pyridoxamine phosphate, having similar biological effects, each of them is called vitamin B6.
Some important plant sources are yeast and outer coating of cereals like wheat, rice, maize etc., and animal sources are meat, liver and egg yolk.
Vitamin B6 acts as coenzymes in the form of pyridoxal phosphate and pyridoxamine phosphate in amino acid metabolism. These coenzymes are required for the actions of the enzymes involved in transami nation, decarboxylation and deamination of amino acids. It takes part in synthesis of sphingomyelin lipids that are constituents of myelin sheath of nerves.
Deficiency of pyridoxine alone is very rare because it is present in many food materials containing other vitamins. Therefore, deficiency of pyridoxine is often associated with deficiency of other vitamins too.
The name pantothenic acid was given to this another of the water soluble vitamins because of its widespread distribution.
It is widely distributed in nature. Animal products like liver, egg, milk and meat are very good sources. Sweet potato, legumes, nuts, fresh fruits and vegetables are important plant sources but they contain considerably less than the animal products.
Being a constituent of coenzyme A, pantothenic acid is required in the formation and metabolism of acetyl CoA and acyl CoA and thereby involved in carbohydrate and lipid metabolism.
Deficiency of pantothenic acid is very rare because it is present in most of the foodstuffs and synthesized in the intestine by bacteria.
This is one other of the water soluble vitamins was also named as vitamin H or anti egg-white injury factor.
It is found widely in animal and plant products i.e., liver, kidney, egg yolk, milk, yeast, legumes, peanuts, molasses, tomato, green vegetables etc. It is also synthesized by intestinal bacteria.
Biotin acts as coenzyme for the enzymes catalyzing carboxylation reactions.
Deficiency of biotin does not normally occur due to its lack in diet because it is widely distributed in nature and is also synthesized by the intestinal bacteria. Deficiency of biotin may occur due to antibiotic therapy that kills the intestinal bacteria or presence of excess raw egg-white in diet because it contains a protein avidin which is anti vitamin of biotin.
This water soluble vitamin was termed anti pernicious anemia factor or vitamin B12. It is a compound of cobalt, and it is called cobalamin.
It is abundant in animal products e.g., liver, meat, fish, egg yolk, milk, cheese etc. In man, vitamin B12 is synthesized by intestinal bacteria but this is not adequate to meet its requirement. However, sufficient vitamin B12 is synthesized in the stomach of herbivorous animals by the action of bacteria.
Cobalamins act as coenzyme in the form of cobamide which is involved in the formation of DNA. It also helps in the action of folic acid.
Pernicious or megaloblastic or macrocytic anemia and Disorers of nervous system including demyelination and degeneration of nerves, loss of sensation and even paralysis are the deficiency symptoms of it.