B-complex vitamins are a class of water soluble vitamins which are responsible for the proper functioning of our body systems.

Vitamin B12 DATS(Digestion, Absorption, Transportation And Storage)

DATS (DIGESTION, ABSORPTION, TRANSPORTATION AND STORAGE) OF VITAMIN-B12 Cobalamin

Vitamin B12 are also known as Cobalamin. It is a common generic term for a group of compounds called coronoids because of their corrin nucleus. The general compounds of cobalamin are Hydroxy cobalamin, Cyano cobalamin, Aqua cobalamin, Nitro cobalamin, 5 deoxyadenosylcobalamin, and methyl cobalamin.

Sources:

The only dietary source of cobalamin are the animal sources which derived it from other microorganisms. The naturally found B12 are only produced by microorganisms like bacteria. Plants, fungi and animals cannot produced it by its own. If the plant contain trace amount of this vitamin than it is probably due to any kind of contamination. Contaminated hands taking food into mouth can also contain Vitamin B12.

The best sources of cobalamin are

sources

Amount of Vitamin C in 100 grams

meat

0.6 micro gram

egg

1.1 micro gram

chicken

0.3 micro gram

milk

0.5 micro gram

Poultry products, cottage cheese, yogurt and in sea sources fishes, shell fish especially calms and oyster are the best sources of Vitamin B12.

RDA (recommended dietary allowances):

The recommended dietary allowances are different for the individuals of different age groups. RDA for males, females and children’s are:

Gender

RDA

Men

2.4 micro gram

Women

2.4 micro gram

Children

0.9-1.2 micro gram

 

Functions of vitamin B12 in Human body:

Vitamin B12 performs many important roles in human body these are:

  • It helps in the proper functioning of the central nervous system.
  • It works with folic acid for the formation of new red blood cells.
  • It acts as a co enzyme and help in body’s chemical reactions.
  • Vitamin B12 also helps in the synthesis of DNA and RNA.

DATS (digestion, absorption, transportation and storage) of vitamin C:

Injested proteins must be released from the protein/ polypeptides to which they are bind. Salivary glands in mouth releases hepatocorrin( R protein). This R protein binds cobalamin releases from proteins. The R-Vitamin B12 complex are formed. This R-Vitamin B12 complex than travels towards stomach where parietal cell releases HCl and intrinsic factors however chief cell releases gastrin and pepsinogen. These gastric juices are mainly responsible for the digestion of food. Thrpugh the action of pancreatic proteases the vitamin B12 detaches from the intrinsic factor. These hepatocorrins and If are attaches to the Vitamin B12 to protect it from bacterial use.

The absorption occurs through out the small intestine. Most of the absorption of vitamin B12 occurs at the terminal portion of ileum. However, the absorption occurs at the overall section of ileum. 1-3% of absorption also occurs through passive diffusion. After absorption cubulin receptors are present which bind the Vitamin B12 receptors and the intrinsic factor is released. Through hepatic circulation this vitamin travels towards liver.

These cubulin recepors are of three types: TC1, TC2 and TC3 receptors. TC1 receptor are the circulating receptor and storage receptor which transport vitamin B12 to different body tissues while TC2 receptor are the tissue receptor which bind vitamin B12 for tissue usage. The function of TC3 receptor are still unknown. 80% of the vitamin B12 transportation occurs through TC1 receptor and 20% occurs through TC2 receptor. On the surface of ileum these receptors are present.

Hepatic portal circulation is important for vitamin nuriture. Unlike other water soluble vitamins vitamin B12 is stored and retained for a long period of time. About 2-4 mg of the vitamin is stored in body mainly 50% in liver. Small amount are also present in the muscle, bones, kidney, heart, brain and spleen.

Vitamin B12 transported form in blood is transcobalamin.

A very little urinary excretion of vitamin B12 occurs. The protein called megalin produced in renal tubules which cauases the reabsorption of vitamin due to which the losses are very low. About 1.4 micro gram of cobalamin are excreted out of the body through urine eah day.                              

Toxicity:

Although no clear toxicity has been reported yet. No tolerable upper limit for Vitamin B12 intake are still established.

Megaloblastic anemia (disease caused by Vitamin B12 deficiency):

The deficiency of Vitamin B12 leads to megaloblastic anemia. The earlier sign and symptoms of vitamin B12 deficiency are numbness and tingling, fatigue, muscle weakening, shortness of breath, unsteady movements, slow healing and anemia.

Megaloblastic anemia and pernicious anemia is an autoimmune disorder in which body produces anti bodies that attack gastric parietal cells and there by diminished the production of IF (intrinsic factor). As due to diminished IF production Vitamin B12 does not absorb properly. Deficiency of Vitamin B12 leads to low production of red blood cells which ultimately leads to anemia. Megaloblastic anemia or macrocytic anemia is a form of anemia characterized by very large red blood cells and a decrease in a number of red blood cells.

The deficiency of vitamin B12 may occur due to the following reasons:

Dietary intake: a vegetarian person not taking fortified food are most likely to develop Vitamin B12 deficiency.

Chronic pancreatis in which pancrease is unable to secrete its juices due to which like other nutrients Vitamin B12 also does not absorbed.

Bacterial over growth in peyer’s patches of ileum causes the mal absorption.

Diet include 1 chicken breast for infants, 1 cup of plan low fat yogurt, 1 cup of milk for men and women and 1 hard boil egg for children may fulfill the requirements of vitamin B12.