Vitamin B12 is a water soluble, red crystalline substance (the red color is due to cobalt in the molecule). A protein in the stomach secretions binds with B12 to help with absorption. Without this protein (called intrinsic factor) less than 1% of vitamin B12 is absorbed. Large amounts of B12 are stored in the liver.
Vitamin B12 is required for the synthesis of myelin, which is the covering around the nerves. It is very important for a healthy nervous system. Vitamin B12 is involved in various aspects of protein, fat, and carbohydrate metabolism. It is an essential growth factor and plays a vital role in the metabolism of all cells, especially those of the gastrointestinal tract and bone marrow. Vitamin B12 is necessary for blood cells to mature.
Anemia is the first symptom of vitamin B12 deficiency. Pernicious anemia occurs when there is inadequate vitamin B12 intake or there is reduced secretion of intrinsic factor, which will inhibit B12 absorption.
Dietary Sources of B12 (Vegans: See Below)
1. Organ meats
To get the full benefit of a vegan diet, vegans should do one of the following:
- eat fortified foods two or three times a day to get at least three micrograms (μg or mcg) of B12 a day or
- take one B supplement daily providing at least 10 micrograms or
- take a weekly B12 supplement providing at least 2000 micrograms.