Elementary plant Biochemistry and Biotechnology (2+1)

Fat-soluble vitamins

• The fat-soluble vitamins are soluble in fat and other nonpolar solvents.
  
• All are synthesized fully or partly from isoprene units and excess quantities are stored in fat containing cells.
• The fat-soluble vitamins appear not to function as components of coenzymes but to serve other important roles.
• The important dietary sources, functions and deficient diseases associated with fat-soluble vitamins are presented.

Fat-soluble vitamins

Vitamin	Functions	Some common dietary sources	Deficiency symptoms
Vitamin A	Visual cycle and maintaining epithelial cells	Fruits, vegetables, fish-liver oils	Night blindness and eventually total blindness, anorexia (appetite loss), dermatitis, recurrent infections; in children, cessation of skeletal growth and lesions in the central nervous system.
Vitamin D	Calcium metabolism	Fish-liver oil	Bone pain and skeletal deformities such as bowlegs (Rickets) and knock-knee in children. Osteomalacia in adults.
Vitamin E	Antioxidant	Plant oils, green leafy vegetables, milk, eggs, meat	Symptoms in humans, if any, are controversial; possibly anaemia
Vitamin K	Blood clotting	Leafy vegetables, soybeans, vegetable oils	Impaired blood clotting