Vitamin requirements vary from species to species and are influenced by age, sex, and physiological conditions such as pregnancy, breast-feeding, physical exercise, and nutrition.

:Vitamins are classified as The lipid-soluble vitamins include vitamins A, D, E, and K the water-soluble vitamin include vitamins B1(thiamin),B2 (riboflavin),folic acid (folcine), H(biotin). Color atlas of biochemistry

Harper’s Illustrated Biochemistry

In the body, biotin is covalently attached via a lysine side chain to enzyme that catalyze carboxylation reactions. Biotin-dependent carboxylases include pyruvate carboxylase and acetyl-CoA carboxylase.

CO2 binds, using up ATP, to one of the two N atoms of biotin. Play an important role in fat, amino acid,and carbohydrate metabolism. Color atlas of biochemistry

Biotin deficiency is extremely rare. Some potential causes of biotin deficiency are: intravenous feeding. eating raw egg whites on a regular basis. carboxylase deficiency. Supplementing with biotin appears helpful for the treatment of this deficiency.

Impaired fat and carbohydrate metabolism alopecia and a characteristic scaly, erythematous dermatitis Harper’s Illustrated Biochemistry,

Folacin * Folic acid, folate,vit.B9 *water-soluble vitamin

Source

Biochemical role - Essential role in Metabolism -Red blood cells, white blood cells, or cells of the intestinal mucous membrane pharmacotherapy

Biochemical role monoglutamate Small intestine tetrahydrofolate cobalamin-dependent reaction Folacin (polyglutamate form ) pharmacotherapy

tetrahydrofolate Biochemical role choline methionine pyrimidine carrier purine

Biochemical role - decrease the incidence of neural tube defects without masking occult vitamin B12 deficiency.

Deficiency of folacin Causes: Inadequate dietary intake malnutrition malabsorption increased utilization Martindale

Risk factors: * Pregnancy or lactation *malignancy *liver disease *alcoholism *chronic hemolytic anemia *Elevated homocysteine level in the blood

Symptoms: *Sore mouth *Diarrhea *Irritability and forgetfulness Handbook of nonprescription drugs

Diseases *Megaloblastic Anemia - -Affects cells that are dividing rapidly - they have a large requirement for thymidine for DNA synthesis. - affects the bone marrow

Diseases *environmental carcinogens. * promotes the breakage of chromosomes at fragile sties. *prohibit normal differentiation and replication