As with any vitamin, this B vitamin acts as a key to turn on various functions in the body. B12 is most associated with assisting in the maturation of red blood cells and, therefore, associated with anemia. Anemia is the poor distribution of oxygen due to the poor functioning of these RBCs.

Many people are sensitive to low B12. They will feel fatigued, or will notice that they are pale from lack of oxygen. One quick way to check for low B12 is to look under the eye lids. If they are pale and not pink, it suggests that the oxygen is low which suggests that there is a low amount of red blood cells.

There are blood tests that help identify B12 deficiency. Looking at RBCs is one way of identifying B12 deficiency in the body. Most lab tests look at red blood cells in a few ways. Of particular interest here is their size and shape. The common CBC, or “Complete Blood Count,” will list MCV. This is “Mean Corpuscular Volume,” translated as “Average Red Blood Cell Size.” As red blood cells mature they get smaller. Therefore, if the MCV is large (greater than 100) it suggests that a person might be low in B12. There is also a less common, more direct and more expensive B12 count available from the lab.

B12 comes in a variety of forms. Cyano-, hydroxy- and methyl-cobalamin. Cyano-cobalamin is the most common form. Methyl- is the strongest. It is commonly believed that the body uses about 1,000 micrograms (mcg) per month, though some individuals with Chronic Fatigue Syndrome are known to benefit from 1,000 mcgs or more of the strong methyl-cobalamin every day.

B12 has the most complex route of entry into the body. All of the other B vitamins get absorbed quickly at the top of the stomach. And, even though B12 is also water soluble, it needs to attach itself to a carrier protein (Intrinsic Factor) and get transported down to the bottom of the small intestines before it gets absorbed. This complex route of entry makes B12 particularly susceptible to being deficient.

Intrinsic Factor comes from the Parietal Cells of the stomach which are also responsible for producing the digestive acid famous for acid reflux, or “heartburn.” It is a common observation that the Parietal Cells become stifled when a person is stressed or as they age. A stress response can be triggered early in life and linger for years (as in Post Traumatic Stress Disorder or PTSD). Therefore, this is one way the body can become deficient in B12. It is also why the digestive tract is bypassed often when administering B12 either with a shot or with sublingual tablets (under the tongue). This is a way of getting the B12 needed to live when the normal absorption through the digestive tract from food or pills is compromised.

Since the idea of sub-lingual B12 pills is to bypass the complex digestive tract route of entry, it is important to not simply dissolve the pills and then swallow them. In order to bypass the digestive tract one needs to allow the pills to be absorbed into the capillary bed under the skin, in this case under the tongue. Capillaries are all the really small blood vessels that are routed to every single cell in the body.

Dr. Miles practices Naturopathic Medicine alongside other holistic practitioners at the Catalina Clinic of Integrative Medicine in Catalina, Arizona.