{{B}} Vitamins{{/B}}
Vitamins are organic compounds which are present in certain foods and are essential to the health of men and other animals.{{U}} (1) {{/U}}Without these substances, the breakdown and absorption of foods could not occur. Certain vitamins participate in the formation of blood cells, hormones, nervous system chemicals, and genetic materials.{{U}} (2) {{/U}}Fat-soluble vitamins include vitamins A, D, E and K. The water-soluble vitamins include vitamin C and the B-vitamin complex.
Fat-soluble vitamins are usually absorbed with foods that contain fat. Excessive amounts of these vitamins are stored in the body's fat, the liver and kidneys. Because fat-soluble vitamins can be stored, they do not have to be consumed every day.
{{U}} (3) {{/U}}A deficiency of vitamin A leads to skin changes and night blindness, or failure of the eye to adapt to the dark. Vitamin A can be obtained directly from foods of animal origin such as milk, eggs, and liver.{{U}} (4) {{/U}}.
Vitamin D acts muck like a hormone and regulates calcium and phosphorus absorption and metabolism. Some vitamin D is obtained from such foods as eggs, fish, liver, butter, and milk. But humans get most of their vitamin D from exposure of the skin to sunlight. A deficiency of vitamin D leads to bone problems.
The role of vitamin E in the human body has not been established.{{U}} (5) {{/U}}Vitamin E is found in seed oil and wheat.
Vitamin K is necessary for the clotting of blood. It is produced in sufficient quantities by bacteria in the intestine, but is also provided by leafy green vegetables and eggs.
The water-soluble vitamins, C and B complex, cannot be stored and therefore need to be consumed daily to satisfy the body's needs. Vitamin C is important in the formation and maintenance of connective tissue. It protects gums, skin, and mucous membranes. It is mainly found in fruits like oranges.
B-complex vitamins serve a wide range of important metabolic functions and prevent some diseases. They are found mostly in the liver.
A. Vitamins are classified into two groups, that is, the fat-soluble (溶解脂肪的) and the water-soluble (溶解水的) vitamins.
B. Their functions are mainly to enhance the metabolism (新陈代谢) of proteins and fats.
C. It is necessary for a healthy life.
D. Vitamin A is essential for normal growth and for the health of epithelial cells.
E. It has been popularly advocated for a great variety of diseases, but no clear evidence exists that it eases any specific disease.
F. Vitamin A can also be obtained through eating green and yellow fruits and vegetables.