By David Musnick, MD

Vitamin B12 is a member of the B complex of vitamins. It is found in foods of animal origin such as meat , fish, shellfish and eggs. In its natural form, it is known as methyl or adenosyl cobalamine.  Synthetic forms are known as methyl and cyanocobalamin.  It has many roles in your body and works in combination with other B vitamins. Vitamin B12 is essential for folic acid metabolism and for the health of your nervous system and red blood cells. It also plays a key role in achieving normal homocysteine levels. It is important to have adequate amounts of Vitamin B12 in order to prevent anemia (low hematocrit).
 
Vitamin B12 Deficiency
Unlike many of the B vitamins, B12 can be stored in your body.  Normal blood levels range form 200 to900 pg/ml.  A deficiency of VitaminB12 can lead to nerve damage, tingling and burning sensations and memory and cognitive decline.

So how can a person dip too low in this important vitamin?  There are a number of ways:

1. Vegans are at risk because there is no Vitamin B12 in a 100% vegan diet. Other vegetarians are also at risk of Vitamin B12 deficiency.
2. Acid-blocking drugs taken for ulcers or heartburn can raise gastric pH and make binding to intrinsic factors reduced.
3. Aging (older than 60) is associated with reduced stomach acid and can lead to low Vitamin B12 levels.
4. Taking a lot of folic acid can mask a B12 deficiency by making it look like the B12 anemia is going away.
5. Nitric oxide administered by your dentist or doctor can precipitate symptoms of B12 deficiency.

Consider asking your doctor to order a Vitamin B12 level if you fall into any of the above categories or if you have fatigue or coronary artery disease.

Supplementing with B12
It is reasonable to supplement with B12 daily, especially if you have been B12 deficient or if you are over 60.  If your B12 levels are extremely low, you can be treated initially by injections.  You can also replenish your B12 stores with a sublingual formula (letting sublingual B12 dissolve along the mucosa under the tongue or inside cheek).

How Much B12 Should You Take?
If you do not have low B12 levels, you can take the amount in most multiple vitamins or you can take TrueB - Vitamin B complex.   This capsule contains 100 micrograms and is good for maintaining B12 as well as other B vitamin levels.  If you have low B12 levels, you should consider a sublingual form as long as you do not have neurological symptoms.  If you have balance or other neurological symptoms and have a low B12 level, get weekly intramuscular shots.

What Can Be Treated with Vitamin B12?
Anemia, high levels of homocysteine (especially when combined with folic acid), some cases of fatigue, megaloblastic anemia and cognitive dysfunction can be treated with Vitamin B12.

Interactions
If you are experiencing a deficiency in Vitamin B12, avoid Vitamin C as it may destroy dietary B12 and stay away from folic acid in high doses as it can mask low B12 levels.

Summary
Vitamin B12 is a very important B vitamin.  It is recommended that people over the age of 60 should get a B12 blood test.  Supplementation is important if you have a low intake of animal sources of protein or if you have any of the above conditions.

References