Are Vitamin B12 Shots Necessary?

Recently, I was "assaulted" by an advertisement urging people to get routine vitamin B12 injections because "B12 can naturally increase energy and stamina, improve sleep and immune support, reduce stress and anxiety, assist with weight loss, enhance sports performance and much more!" Enhance sports performance? Essentially, the only thing not included was "spice up your love life." There's an old saying... "Never try to pull one over a scientist."

Vitamin B12, otherwise known as cobalamin, plays a critical role in the central nervous system (CNS), blood cell maturation, and DNA replication. Ubiquitously involved in cellular metabolic function, cobalamin is the most structurally complex of vitamins, bearing some resemblance to hemoglobin. Instead of iron as the center of a porphyrin ring, B12 contains cobalt at the center of a corrin ring. Present in the body (blood, plasma, kidney, spleen, pancreas) in the range of 80-300 micrograms (mcg), cobalt is conservatively utilized biochemical element. Vitamin B12 is the human body's primary source of cobalt.

Deficiency in stored and/or systemic cobalt may be caused by alcoholism, Chron's disease, intestinal surgery, pernicious anemia, and certain autoimmune disorders such as systemic lupus erythematosus. It might also result from a vegan diet, as the most abundant sources of B12 derived cobalt are animal products (meat, seafood, poultry, eggs, and milk).

There are a variety of symptoms of cobalt deficiency, amongst which are fatigue, pale skin (indication of anemia), neurological disorders, and easy bruising. In fact, fatigue is the most common reason why medical practitioners administer bolus injections of cobalamin. Such injections range from $25-75 in patient cost. The fundamental question is, "Are vitamin B12 injections necessary?"

Once B12 rich foods are consumed, they are digested in the stomach. All of the cobalamin present in food sources is protein bound (not immediately available), requiring enzymatic liberation for human metabolism. Absorbtion is facilitated by a protein known as "intrinsic factor," otherwise known as gastric intrinsic factor (GIF). Binding of food-derived B12 to GIF is required for transport to the ileum. Only those who have compromised ability to produce GIF are incapable of absorbing B12 via consumption of food. When consumed at high doses in supplements, however, cobalamin can effectively overcome GIF defects via passive diffusion.

Bearing highly polar peripheral amide groups and a charged phosphoribose moiety, cobalamin is one of the most water-soluble vitamins known. Unlike other water-soluble vitamins that are rapidly eliminated via excretion, B12 is stored in the liver. The amount of cobalamin in a typical B-100 supplement is 100 mcg, 0.043 mcg of which is metallic cobalt. This is more than forty times the FDA's Recommended Daily Allowance (RDA). Readily absorbed in the ileum, B12 experiences a very high level of binding to plasma proteins, and has a half-life of approximately 6 days. The half-life of cobalamin in the liver is 400 days. Barring hepatic disease or IF dysfunction, the human body quickly absorbs and stores what B12 it needs in plasma proteins and the liver.

Most B12 shots are administered subcutaneously in a quantity of 1000 mcg or 1 milligram (mg). A structural analog, methylcobalamin delivers a 10 mg equivalent of cobalamin. Hence the most common injection of B12 on the market may be absorbed via the orally consumable equivalent of 10 B-100 tablets. The typical wholesale cost of B-100 tablets from popular distributors is approximately 8 cents each. Hence, the equivalent of a $25-75 cobalamin shot from a nurse practitioner or physician may be taken and absorbed orally for only 80 cents.

There is a common myth perpetuated by certain magazines and websites - B12 shots can be part of a regimen of "medical weight loss." To date, there is absolutely no peer-reviewed evidence published in medical journals supporting such claims. In all likelihood the placebo effect of the injection imparts elevated mood leading to increased levels of activity, thereby increasing metabolism. The bottom line is this. If there is an unusual disorder which impedes food-derived or supplemental B12 absorption, then there is need for bolus injection of B12 to maintain health. In lack of corroborating evidence for such a disorder, then there is no perceptible advantage in getting B12 subcutaneous injections.

Mostly unknown to the public is the potential for dangerous side effects of "B12 abuse," including diarrhea, confusion, dizziness and breathing difficulty. The Mayo clinic reports in rare cases, excessive intake of cobalamin via supplements and injection can lead to "peripheral vascular thrombosis, an arterial blockage in the arms and legs that causes pain, numbness and ulcers."

On a finishing note, one strategically and effectively superior use of an injectible B12 analog, hydroxycobalamin, is for the treatment of cyanide poisoning. Hydroxycobalamin binds cyanide to form cyanocobalamin, a harmless acid-base adduct, which is eliminated via urination. This treatment is far less complex and invasive than the traditional inhalation of amyl nitrite, i.v. administration of sodium nitrite, followed by i.v. administration of sodium thiosulfate.