Vitamin A: - Vitamin A is a fat-soluble vitamin that is stored in the liver. - It is absorbed in the small intestine and transported to the liver where it is converted into retinol. - Retinol is then converted into retinal and retinoic acid, which are the active forms of vitamin A that are used by the body. - Retinal is important for vision, while retinoic acid is involved in gene expression and cell differentiation.
Vitamin D: - Vitamin D is also a fat-soluble vitamin that is stored in the liver and fat tissues. - It is obtained from sunlight exposure, dietary sources, and supplements. - In the skin, sunlight converts a precursor molecule into vitamin D3, which is then transported to the liver and converted into 25-hydroxyvitamin D. - 25-hydroxyvitamin D is then converted into the active form, 1,25-dihydroxyvitamin D, in the kidneys. - 1,25-dihydroxyvitamin D is important for calcium absorption and bone health.
Vitamin E: - Vitamin E is a fat-soluble antioxidant that is stored in adipose tissue. - It is absorbed in the small intestine and transported to the liver where it is incorporated into lipoproteins for distribution throughout the body. - Vitamin E protects cells from oxidative damage by neutralizing free radicals.
Vitamin K: - Vitamin K is a fat-soluble vitamin that is stored in the liver. - It is obtained from dietary sources and synthesized by gut bacteria. - Vitamin K is important for blood clotting and bone health. - In the liver, vitamin K is converted into its active form, vitamin K-dependent clotting factors, which are involved in the blood clotting cascade.
0
Google Gemini AI
more than 3 weeks ago
Vitamin A
- Absorption: In the small intestine, vitamin A is absorbed as retinol and beta-carotene. - Transport: Retinol is bound to retinol-binding protein (RBP) and transported to the liver. - Storage: In the liver, retinol is stored as retinyl esters. - Mobilization: When needed, retinyl esters are mobilized from the liver and transported to target tissues. - Conversion to active form: In target tissues, retinol is converted to retinal and then to retinoic acid, which is the active form of vitamin A.
Vitamin D
- Absorption: In the skin, vitamin D is synthesized from 7-dehydrocholesterol upon exposure to ultraviolet B (UVB) radiation. Can also be absorbed from the diet. - Transport: Vitamin D is transported in the blood bound to vitamin D-binding protein (DBP). - Storage: Vitamin D is stored in the liver and adipose tissue. - Activation: In the liver, vitamin D is hydroxylated to 25-hydroxyvitamin D (25(OH)D). In the kidneys, 25(OH)D is further hydroxylated to 1,25-dihydroxyvitamin D (1,25(OH)2D), which is the active form of vitamin D.
Vitamin E
- Absorption: Vitamin E is absorbed in the small intestine with the help of bile acids and fats. - Transport: Vitamin E is transported to the liver bound to lipoproteins. - Storage: Vitamin E is stored in the liver, adipose tissue, and other tissues. - Mobilization: When needed, vitamin E is mobilized from storage and transported to target tissues. - Antioxidant function: Vitamin E acts as an antioxidant, protecting cells from damage caused by free radicals.
Vitamin K
- Absorption: Vitamin K is absorbed in the small intestine with the help of bile acids and fats. - Transport: Vitamin K is transported to the liver bound to lipoproteins. - Storage: Vitamin K is stored in the liver and adipose tissue. - Mobilization: When needed, vitamin K is mobilized from storage and transported to target tissues. - Role in coagulation: Vitamin K is essential for the synthesis of clotting factors.