Reviewed By: Pramod Kerkar, MD, FFARCSI

Why Do We Need Vitamin B-12?

Vitamin B-12 is exclusively produced by a microorganism and one can obtain by consuming meat foods and dairy products. It is a water-soluble vitamin, essential for human physiology. It is used as a co-factor by some enzymes such as methionine synthase and l-methyl-malonyl-coenzyme A mutase. B-12 is one of the important factors for gene synthesis, red blood cell synthesis, and for maintaining normal neurologic function. Its classic deficiency syndrome is pernicious anemia, malabsorption, and neurologic manifestation.

How Much Vitamin B-12 Should You Take A Day?

How Much Vitamin B-12 Should You Take A Day?

According to NIH, vitamin B-12 is daily essential for normal metabolism of a human being. The amount of requirement of B-12 is depended on the age factor.

Life Stage Per Day Recommended Amount (microgram-mcg)
Child Birth to 6 months 0.4 mcg
Infants 7-12 months 0.5 mcg
Children 1-3 years 0.9 mcg
Children 4-8 years 1.2 mcg
Children 9-13 years 1.8 mcg
Teens 14-18 years 2.4 mcg
Adults 2.4 mcg
Pregnant teens and women 2.6 mcg
Breastfeeding teens and women 2.8 mcg

*NIH Factsheet

When compared to other vitamin, B-12 doesn’t require in a large amount per day. A small microgram 2.4 mcg is more enough per day which it is easily available for people in the form of fortified foods. Intake of fortified foods is easy for people, particularly who are above 50 years. Aged people have difficulties in the absorption of nutrients, to over this hurdles food industries makes higher bioavailability food products. This means the breakdown of the nutritious compound is not necessary; instead, it reaches the systemic circulation directly after absorption without unchanged. Vitamin B-12 enriched dietary supplements have bioavailability beneficial for old people who have improper dieting. Supplementation of 25-100 mcg per day has been used to maintain vitamin B12 levels in older people.

Vitamin B-12 absorption may interfere in those who use alcohol excessively. Certain medications like high dose antibiotics, stomach-acid controlling medicines like H2 blockers and proton pump inhibitors, and anti-diabetes drugs can inhibit the absorption. Smoking tobacco can significantly lower the serum levels of B-12 every day. Thus, anemia is common among nicotine user. In addition, potassium supplements can reduce absorption of vitamin B12, and there is some evidence that vitamin C in supplements can interfere with obtaining the B12 vitamin found in foods.

How Vitamin B-12 Absorbed in Human Body?

The human body absorbs B-12 from food by basic steps. The stomach acids, i.e. HCL in the stomach separates B-12 from the other compound such protein, lipid and other compound. With the help of intrinsic factor, B-12 absorbed well and reaches the circulatory system. If human body lacks this intrinsic factor, the person may suffer from pernicious anemia. Hence, B-12 helps to prevent anemia called megaloblastic anemia which makes the person fatigue. This condition is serious which may cause inhibition of DNA synthesis during RBC production.

What Is The Outcome Of Vitamin B12 Deficiency?

Vitamin B-12 deficiency can cause other nutrient deficiencies such as other B vitamins. Folate, riboflavin, and choline deficiency can cause risk of adverse perinatal outcomes. B-12 or folate deficiency can cause impaired DNA synthesis and cause megaloblastic anemia. Vitamin B-12 about 300 mcg per day is recommended for people anemia.

  • Vitamin B-12 as a Therapeutic Agent
  • General supplemental dose - up to 25 mcg per day
  • Pernicious anemia - cyanocobalamin about 300 mcg/day.
  • For high blood levels of homocysteine -500 mcg in combination with 0.54-5 mg folic acid and 16.5 mg pyridoxine.
  • For preventing age-related macular degeneration (AMD): vitamin B12 1 mg, folic acid 2.5 mg, and pyridoxine 50 mg daily.
  • For atopic dermatitis – B-12 0.07% cream applied twice daily.
  • For psoriasis: B-12 0.7 mg/gram applied for 12 weeks twice daily.
  • Some exceptional cases, vitamin B-12 is used in the form of injection.
  • For pernicious anemia -100 mcg IM/SC once daily for 6 to 7 days.
  • For a hereditary condition that causes vitamin B12 malabsorption (Imerslund-Grasbeck disease) - hydroxocobalamin injected into the muscle at a dose of 1 mg daily for 10 days.
  • For cyanide poisoning: Hydroxocobalamin (Cyanokit) has been given intravenously (by IV) for a total dose of up to 10 grams.

Also Read:

Pramod Kerkar

Written, Edited or Reviewed By:

, MD,FFARCSI

Pain Assist Inc.

Last Modified On: June 29, 2018

This article does not provide medical advice. See disclaimer

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