What’s the Deal With B12?

Published: January 29th, 2013   |   Author: Jessica Levine

Some claim this wonder supplement can boost energy, athletic performance, brain power, and weight loss.


From big celebs like Madonna to college athletes, people are talking up the powers of one little vitamin. They claim B12 injections are the answer to fight fatigue, increase endurance, clear up confusion, and even shed stubborn pounds. But before you roll up your sleeves and run out for a shot of the stuff, a couple experts have some advice on the topic.

What It Does Do
Like other essential nutrients, vitamin B12 is pretty amazing—from keeping homocysteine levels (a risk factor for heart disease) in check to protecting against dementia. “Vitamin B12 is essential for important chemical reactions in the body that contribute to red blood cell production, nervous system function, and DNA synthesis,” says Joel Fuhrman, MD, author of Eat to Live. A deficiency puts you at risk for depression, confusion and memory loss, fatigue, and anemia, he says.

What It Doesn’t Do
Research shows taking a B12 supplement won’t boost energy, athletic performance, brainpower, or weight loss—unless you’re deficient to begin with. “I’m really not thrilled with people wanting to get B12 shots for energy or to lose weight,” says Lauren O’Connor, RD, the LA dietitian behind the blog Nutri-Savvy. “It really should be a decision based on medical need, not to boost energy and mood, as it can be easily obtained through a varied, healthful, balanced diet.”

Who Needs More
Your B12 levels are likely fine if you’re under 60 and eat meat and dairy, which are the richest sources of the nutrient. However, “B12 deficiency is relatively common in vegans who don’t take supplements and in elderly people,” Dr. Fuhrman says. “B12 absorption decreases with age, and about one-fifth of adults over age 60 have insufficient B12 levels.”

Signs of deficiency may include headache, fatigue, shortness of breath, and heart palpitations. If you think you could be B12 deficient, see your doctor to get your levels checked. “Remember to consider lifestyle factors,” O’Connor says. “Are you getting enough sleep? Are you stressed? Adequate sleep and stress reduction, along with a heart-healthy lifestyle, can improve your energy levels and your mood.” And she says if your primary symptom is tiredness or fatigue, it’s easy enough to get the recommended daily allowance through a balanced diet.

How to Get More
If you're into clams, you're in luck because just 3 ounces packs a whopping 1,400% of the recommended daily value, which is just 6.0 micrograms. Other good sources include chicken, salmon, trout, tuna, yogurt, milk, cheese, eggs, and fortified cereals, breads, crackers, and alternative milks like almond, coconut, soy, O’Connor says. Given the range of B12-packing foods, most people can get enough through diet. But if it turns out you are deficient, ask your doctor what kind of supplement might be best for you.

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