A B12 deficiency - in data
New York Yankees pitcher Roger Clemens is feeling the heat. A former trainer has said he injected the seven-time Cy Young winner with steroids and human growth hormone, but Clemens says the only injections he received were of vitamin B12 and lidocaine, an analgesic. Lidocaine is sometimes injected into joints to dull joint pain -- a potential problem for an aging athlete -- but B12 injections are more commonly used to treat pernicious anemia and address diet deficiencies in the elderly. Physicians generally believe that the well-nourished rank-and-file don’t need it, but the vitamin hasn’t lost its luster among those who say it boosts energy.
Vitamin B12 is an essential vitamin found primarily in animal foods. The body uses it in the formation of DNA and red blood cells, and it’s necessary for the healthy functioning of the nervous system. For people who are deficient or at risk of deficiency, injections can be helpful. For a well-nourished pitcher hoping to improve his fastball, not so much.
“Some athletes believe that vitamin B12 injections will increase oxygen [supply to the muscles] and that that enhances performance,” says Andrea Giancoli, a spokeswoman for the American Dietetic Assn. and consultant for the L.A. Unified School District on nutrition and policy. “But in the absence of a vitamin B12 deficiency, the studies don’t support that.”
Aside from a 1989 report in the International Journal for Vitamin and Nutrition Research, which found that a combination of B1 (thiamin), B6 (pyridoxine) and B12 (cyanocobalamin) improved fine motor skill in target shooting, the evidence is scant, writes Thomas Brenna, professor of human nutrition at Cornell University, in an e-mail.
And B12 injections are not going to give the average person an energy boost, says Dr. David Baron, chief of staff at Santa Monica-UCLA Medical Center and Orthopaedic Hospital.
“For my entire career, I have encountered patients who have requested B12 shots, and I’ve been explaining to them that they serve no useful purpose,” Baron says. “Honestly, this is an argument that’s been going on between Western scientific physicians and complementary and alternative healthcare providers for many, many years.”
Some weight-loss programs even recommend B12 injections, says James Hill, director of the human nutrition center at the University of Colorado. “But there’s no indication that they’re doing any good,” he says.
In fact, when the body is drenched with B12, the kidneys will filter out whatever isn’t needed, says Dr. Michael Karp, an internist and assistant professor of clinical medicine at USC School of Medicine. The upside is that too much B12 probably won’t hurt you, he says.
The basis for the belief that vitamin B12 shots can provide energy goes back decades, Baron says. “Before we knew how to manufacture B12 in an injectable form, people who were deficient for various reasons were quite ill,” he says. Once physicians began giving B12 shots to this population, “people who were horribly chronically anemic from B12 deficiency just basically came to life,” he says. “It was a miracle.”
The average person needs 2.4 micrograms of B12 per day, and most people get sufficient amounts in their food, particularly given how many foods -- such as cereals, nondairy milk, meat substitutes and protein bars -- are now fortified with B12, Giancoli says.
Vitamin B12 has a somewhat tangled path to absorption. The vitamin needs an acidic environment in the stomach in order to be released from food. It then binds with a glyco-protein compound called intrinsic factor, which allows it to be absorbed through the small intestine. If the stomach doesn’t have a sufficient hydrochloric acid or lacks intrinsic factor, absorption will be limited.
To be sure, a deficiency of B12 can have serious consequences -- including pernicious anemia and nerve damage. “The nerve damage can start with memory problems, declined cognitive function, tingling in the extremities and can progress,” Giancoli says. “And the neurological changes may not be apparent in everyone. There may be very general symptoms, like fatigue, weakness, weight loss, constipation, loss of appetite.”
People most at risk for B12 deficiency are patients with certain types of gastrointestinal disorders (such as Crohn’s disease), vegans and the elderly. The elderly are at risk for a number of reasons, says Dr. Marie Bernard, a spokeswoman for the American Geriatrics Society.
“As you get older, you’re more likely to have accumulated medical problems that might prevent you from absorbing B12 optimally,” Bernard says. Those events would include surgery to remove part of the intestine, and use of certain medications, such as acid-suppressing drugs.
As for that other segment clamoring for injections -- the worried well who believe the shots boost energy -- B12 may also have a benefit of sorts: a nice little placebo effect.
“Quite frankly,” Karp says, “I’ll sometimes get a new patient who says that they’re getting a monthly vitamin B12 injection and that it makes them feel better, so I’ll continue to give it to them. If it makes them feel better, that’s still something.”
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