vitamin

Examples of vitamin in the following topics:

• Role of Vitamin K

  • Vitamin K is a fat soluble vitamin necessary for synthesis of many coagulation factors involved in the coagulation cascade.
  • Vitamin K can be inhibited by the anticoagulant drug warfarin, which acts as an antagonist for vitamin K.
  • Warfarin's effects can be overcome by ingesting more vitamin K to reactivated the coagulation factor synthesis pathway.
  • Vitamin K deficiency can occur from dietary causes, from malabsorption in the intestines, or liver failure (which is involved in vitamin K metabolism).
  • Calcium is also required to to synthesize the anticoagulant Protein C (along with vitamin K).

• Osteomalacia and Rickets

  • Women who avoid sun exposure have very low levels of vitamin D.
  • The predominant cause is a vitamin D deficiency.
  • Vitamin D is required for proper calcium absorption from the gut.
  • Treatment involves increasing dietary intake of calcium, phosphates, and vitamin D.
  • Vitamin D3 (cholecalciferol) is the preferred form since it is more readily-absorbed than vitamin D2.

• Bacterial Flora

  • These bacteria also produce large amounts of vitamins, especially vitamin K and biotin (a B vitamin), for absorption into the blood.
  • Although this source of vitamins, in general, provides only a small part of the daily requirement, it makes a significant contribution when dietary vitamin intake is low.
  • An individual that depends on absorption of vitamins formed by bacteria in the large intestine may become vitamin-deficient if treated with antibiotics that inhibit other species of bacteria as well as the disease-causing bacteria.

• Digestive Processes of the Large Intestine

  • In the large intestine, a host of microorganisms known as "gut flora" help digest remaining food matter and create vitamins.
  • The colon absorbs vitamins created by the colonic bacteria—such as vitamin K (especially important as the daily ingestion of vitamin K is not normally enough to maintain adequate blood coagulation), vitamin B12, thiamine, and riboflavin.
  • Though people can survive without gut flora, the microorganisms perform a host of useful functions, such as fermenting unused energy substrates, training the immune system, preventing growth of harmful, pathogenic bacteria, regulating the development of the gut, producing vitamins for the host (such as biotin and vitamin K), and producing hormones to direct the host to store fats.
  • Evidence also indicates that bacteria enhance the absorption and storage of lipids and produce/aid the absorption of needed vitamins like vitamin K.

• Absorption and Feces Formation in the Large Intestine

  • Intestinal bacteria also produce large amounts of vitamins, especially vitamin K and biotin (a B vitamin), which are absorbed into the blood.
  • Although this source of vitamins provides only a small part of the daily requirement, it makes a significant contribution when dietary vitamin intake is low.
  • An individual that depends on absorption of vitamins formed by bacteria in the large intestine may become vitamin-deficient if treated with antibiotics that inhibit other species of bacteria while targeting the disease-causing bacteria.

• Metabolic Functions

  • One of the metabolic functions of the skin is the production of Vitamin D3 when ultraviolet light reacts with 7-dehydrocholesterol.
  • Vitamin D is produced in the two innermost strata of the epidermis, the stratum basale and stratum spinosum.
  • Vitamin D3 is made in the skin when 7-dehydrocholesterol reacts with ultraviolet light of UVB type at wavelengths between 280 and 315 nm, with peak synthesis occurring between 295 and 297 nm.
  • Depending on the intensity of UVB rays and the minutes of exposure, an equilibrium can develop in the skin, and vitamin D degrades as fast as it is generated.

• Absorption of Monosaccharides, Amino Acids, Dipeptides, Tripeptides, Lipids, Electrolytes, Vitamins, and Water

  • Glucose, amino acids, fats, and vitamins are absorbed in the small intestine via the action of hormones and electrolytes.
  • The fat soluble vitamins A, D, and E are absorbed in the upper small intestine.
  • The factors that cause malabsorption of fat can also affect absorption of these vitamins.
  • If intrinsic factor is missing, then Vitamin B12 is not absorbed and pernicious anemia results.
  • Of the water soluble vitamins, transport of Folate and B12 across the apical membrane are Na+ independent, but the other water soluble vitamins are absorbed by Na+ co-transporters.

• Anticoagulants

  • However, they are also the main dietary source of vitamin K, which is necessary for blood clotting to occur.
  • However, if you are taking warfarin to prevent heart attacks, then it is necessary to control intake of leafy green vegetables since warfarin is an antagonist to vitamin K and could work improperly if the diet is high in vitamin K.
  • Coumadins such as warfarin are oral anticoagulant pharmaceuticals that antagonize the effects of vitamin K1.
  • Depletion of vitamin K by coumadin therapy increases risk of arterial calcification and heart valve calcification, especially if too much vitamin D is present.

• Bone and Calcium Homeostasis

  • Older individuals living in nursing homes tend to have inadequate levels of vitamin D, which factors into their high rates of osteoporosis and increased danger from falling.
  • Supplementation with vitamin D and calcium slightly improves bone mineral density, as well as decreases the risk of falls and fractures in certain groups of people.
  • Vitamin D is converted to calcidiol in the liver.
  • Part of the calcidiol is converted by the kidneys to calcitriol, the biologically active form of vitamin D.

• Onset, Duration, and Half-Life of Hormone Activity

  • Vitamin D (which is actually a hormone) has a half-life of around one to two months.
  • If one obtains vitamin D solely through sun (UVB) exposure during the summer months, serum vitamin D levels will be critically low by late winter.
  • This is one reason why current recommendations are to take vitamin D supplements in order to maintain serum vitamin D levels throughout the year.