vitamin

Examples of vitamin in the following topics:

• Lipid Soluble Vitamins

  • The essential dietary substances called vitamins are commonly classified as "water soluble" or "fat soluble".
  • Water soluble vitamins, such as vitamin C, are rapidly eliminated from the body and their dietary levels need to be relatively high.
  • The RDA for these vitamins are:
  • Vitamin D 5 to 10 μg ( upper limit ca. 2000 μg)
  • Vitamins A is a terpene, and vitamins E and K have long terpene chains attached to an aromatic moiety.

• Vitamins and Amino Acids

  • Microorganisms and plants can synthesize many uncommon amino acids and vitamins.
  • This group of vitamins includes two natural vitamers: vitamin K1 and vitamin K2.
  • No known toxicity exists for vitamins K1 or K2.
  • Three synthetic types of vitamin K are known: vitamins K3, K4, and K5.
  • This is vitamin K1 (phylloquinone).

• 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 refers to a group of fat-soluble steroids responsible for increasing intestinal absorption of calcium, iron, magnesium, phosphate, and zinc.
  • In humans, the most important compounds in this group are vitamin D3 (also known as cholecalciferol) and vitamin D2 (ergocalciferol). 
  • Deficiency in vitamin D has been termed a modern disorder associated with both a poorer diet and reduced time spent outside.
  • Vitamin D is produced in the two innermost strata of the epidermis, the stratum basale and stratum spinosum.

• Food Requirements and Essential Nutrients

  • Vitamins and minerals are substances found in the food we eat.
  • Each vitamin has its own special role to play.
  • Some fat-soluble vitamins include vitamin A, vitamin K, vitamin D, and vitamin E.
  • Unlike fat-soluble vitamins, they can be destroyed by heat.
  • Some water-soluble vitamins include vitamin B6, vitamin B12, vitamin C, biotin, folic acid, niacin, and riboflavin.

• 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.

• Role of Vitamin K

  • Vitamin K is a fat-soluble vitamin necessary for synthesis of 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 reactivate the coagulation factor synthesis pathway.
  • Vitamin K deficiency  is associated with impaired coagulation function and excessive bleeding and hemorrhage (internal bleeding, often severe).
  • Calcium is also required to to synthesize the anticoagulant Protein C (along with vitamin K).

• 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.

• 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.

• 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.