Vitamin B12 (also known as cobalamin) is vital to the body's proper functioning. It helps build and maintain healthy red blood cells, is involved in the production of DNA and RNA and is instrumental in maintaining a healthy nervous system and cell metabolism.
Because vitamin B12 can be stored in the liver for a number of years and we need just a small amount of it to remain healthy, symptoms of a vitamin B12 deficiency may not show up for a long time. Vegans sometimes find themselves with this deficiency, as animal products are the only food source of vitamin B12 in a form that can be easily utilized by humans. The elderly can also be at risk of deficiency, as our digestive systems have an increasingly difficult time with absorption of the vitamin as we age.
A lack of vitamin B12 can cause a number of problems, including depression, fatigue and memory problems. A severe deficiency can lead to nerve damage or pernicious anemia, a disease that occurs when the stomach becomes unable to produce intrinsic factor, a substance secreted by cells in the stomach that allows the body to absorb B12.
Without B12 your bones can't produce enough healthy red blood cells, instead producing large red blood cells in low numbers. Their large size makes it difficult for them to make their way out of the bones and into the bloodstream where they carry on the important work of getting oxygen to the rest of the body's cells, causing fatigue and other problems.
Some symptoms of vitamin B12 deficiency include:
- Shortness of breath
- Tingling in fingers or toes
- Diarrhea or constipation
Supplementation with vitamin B12 can help reduce your risk of age-related macular degeneration, heart disease (due to its ability to lower homocysteine levels), breast cancer, Alzheimer's disease and male infertility.
Interestingly, neither plants nor animals make vitamin B12. Rather, it is made by various microorganisms, such as bacteria, molds, yeast and algae, that are then consumed by animals and produce the vitamin in their digestive tract.
There are a number of good dietary sources of vitamin B12, among them eggs, dairy products, beef, pork, chicken, fish and shellfish. Organ meats, clams and oysters are particularly high in the vitamin. Vegetarians and vegans should look for vitamin B12 supplements in the form of fortified cereals, nutritional yeast or spirulina.