Vitamin B12 Article

Vitamin B12

Vitamin B12 is a part of the Vitamin B complex. It consists of cobalt and is called cobalamin. Rich sources of vitamin B12 include meat, eggs and dairy products. Vitamin B12 is synthesized only by bacteria. Vitamin B12 is vital for the synthesis of red blood cells, nervous system maintenance and for the growth and development in children. Lack of Vitamin B12 can cause anemia. Vitamin B12 neuropathy is another possible effect of lack. This disorder causes degeneration of nerve fibers and irreparable neurological damage.

Vitamin B12 functions primarily in the formation of red blood cells and in promoting the health of the nervous system. It is also vital for the speedy synthesis of DNA during cell division. This especially critical for tissues where cells divide rapidly particularly in the bone marrow tissues which is responsible for red blood cell formation. Lack of Vitamin B12 will cause disruption to the DNA production resulting in the presence of abnormal cells called megaloblasts. This condition leads to anemia. Symptoms of anemia include excessive tiredness, breathlessness, restlessness, pallor and poor resistance to infection. Other symptoms that will manifest include smooth, sore tongue and menstrual disorders. Anemia could also be a result of folic acid deficiency since folic acid is a vital for DNA synthesis too.

Vitamin B12 promotes healthy nervous system. The nerves are surrounded by a fatty sheath that insulates it and is made up of complex protein called myelin. Vitamin B12 is important in the metabolism of fatty acids which is vital for the health of myelin. Lack of B12 for an extended period of time can cause nerve degeneration as well as irreversible neurological damage.

The deficiency of vitamin B12 is mainly caused by failure of the intestine to fully absorb B12 instead of diet problems. In order to effectively absorb vitamin B12, the cells lining the stomach must secret a glycoprotein called intrinsic factor. B12-intrinsic factor complex is absorbed in the ileum which is found in the small intestine with the aid of calcium. Some people cannot produce the intrinsic factor and the resulting pernicious anemia is treated with injections of B12. Vitamin B12 is stored in small amounts by the body for a total of 2-5 mg in adults. Almost 80% of these are found in the liver.

Vitamin B12 excreted in the bile is reabsorbed by the body. This is known as enterohepatic circulation. B12 excreted in the bile ranges from 1 to 10 ug (micrograms) per day. People who have low B12 intake such as vegans and vegetarians can obtain more B12 from reabsorption. Reabsorption is the factor why it can take 20 years for deficiency disease to develop in people who changed diets that are low in vitamin B12. However, if B12 deficiency is caused by failure in absorption as discussed earlier, the disease can occur in 3 years.

Rich sources of vitamin B12 include meat, dairy products and eggs. Recommended Daily Amounts (RDA’s) are now replaced by the tern Reference Nutrient Intake (RNI). RNI according to age include: for 0 to 6 months- 0.3 ug; 7 to 12 months – 0.4 ug; 1 to 3 years – 0.5 ug; 4 to 6 yrs. – 0.8 ug; 7 to 10 yrs.- 1.0 ug; 11 to 14 yrs.- 1.2 ug; 15 and above -1.5 ug and breast feeding women 2.0 ug. Vitamin B12 has low toxicity and can be taken at high dosage without overdose.