Are vitamin B12 shots a safe, effective way to reverse deficiencies, boost energy, and even spur weight loss?

By Cassie Shortsleeve
May 15, 2014
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Vitamin B12 is known for two things: delivering energy and being found mostly in meat, which is why vegans and vegetarians often need to supplement. Now, though, more people are opting to get a B12 shot rather than boost their levels through more traditional means (e.g., a sublingual pill). And it's not just veggie-heads and people who know they're vitamin B12 deficient who are opting for these shots-anyone who's feeling sluggish, drowsy, or legthargic is giving it a whirl. But for people who don't have a deficiency, do B12 shots do anything? Or worse, could they be harmful?

"Research shows that when someone is deficient and you supplement-either through a pill or a monthly injection, administered by a doctor-there is an improvement in energy," says Ashley Barrient, R.D., of the Loyola Center for Metabolic Surgery and Bariatric Care, who administers the shots.

But credentialed doctors aren't the only ones administering B12 shots-and warranting patients aren't the only ones lining up for them. Log onto Groupon, walk into a medical spa, juice bar, weight-loss clinic, or even a beauty store and you may notice something: Everyone is making claims about B12: Boost your metabolism! Increase your energy! Lose weight!

And many (reportedly including Madonna, Justin Timberlake, and Charlize Theron!) swear that a prick or a pill is just the fast fix they need. The thought process: Supplementing (no matter your actual B12 levels) will increase energy. "That's not the case, though," says Barrient.

Why? Vitamin B12 is water-soluble: "When taken in excess, your body eliminates what it doesn't need," she says. So if you're not deficient, you're wasting your money. Most accounts from healthy people swearing by B12 boils down to a good ol' placebo effect: If you're told something works wonders, you'll likely to feel that it does, Barrient says.

Are You B12-Deficient?

It's been widely reported that almost 40 percent of Americans could be B12-deficient, according to the Framingham Offspring Study. But if you look more closely at those numbers, you'll see that this study actually found that 39 percent of people had B12 levels in the "low normal" range-well above the accepted level of deficiency. In fact, the National Institutes of Health suggests only one to one and a half percent of people suffer from a shortage. Most of us take in enough from food-milk, eggs, fish, poultry, and fortified cereals (all of which are prominent in the American diet).

That's not to say everyone is safe from lagging levels. Some-vegetarians, vegans, people with Chron's or celiac disease, and those who abuse alcohol-are susceptible to low levels because of diet choices or absorption issues.

But don't succumb to a marketed solution off of a self-diagnosis. See your doc. Signs of low B12 levels (fatigue, weakness, sore tongue, tingling and numbness in your fingers and toes, difficulty walking, mood change, or memory loss) are also symptoms of other medical conditions, says Barrient.

Fallen for the craze (and worried your levels are in the clear)? B12 doesn't build up toxicity like some other vitamins can when taken in excess, says Barrient. That means that you likely won't see any negative side effects from too much. Like cellulite cream, it won't help, but it probably won't hurt.