It’s more difficult for our bodies to absorb nutrients from food as we age. Vitamin B12, in particular, may be lacking from your diet if you follow a plant-based eating plan or are a vegetarian, as it’s commonly found in animal byproducts. But more than these two groups may exhibit signs of a vitamin B12 deficiency—at least 4% of people between 40 and 59 are lacking in the nutrient, and even more are borderline.
Meet the experts: Lisa Cimperman, R.D., a licensed dietitian; Angela Grassi, R.D., a dietitian at the PCOS Nutrition Center
You might also be at risk of B12 deficiency if you take metformin (often prescribed for type 2 diabetes or polycystic ovary syndrome) or certain heartburn medications, if you’ve had weight loss surgery, or if you have a digestive disorder like celiac disease or Crohn’s.
Being too low in vitamin B12 may cause everything from extreme fatigue to wonky vision. Here, dietitians and science reveal telltale signs of a vitamin B12 deficiency. If the symptoms below sound familiar, ask your doctor to run a blood test and check your levels.
Exhaustion
Feeling fatigued, even when you’ve gotten enough sleep? That’s one of the biggest—and earliest—signs you’re low in B12.
“Fatigue is one of the first signs of B12 deficiency,” says Lisa Cimperman, R.D., a licensed dietitian. That’s because your body relies on the nutrient to make red blood cells, which carry oxygen throughout your body. When there’s not enough oxygen in your blood, you’ll feel tired no matter how long you sleep.
Fatigue can mean a number of things, though. So you can’t assume you’re B12-deficient if feeling sleepy is your only complaint—doctors usually are tipped off if you’ve got fatigue plus other symptoms.
Muscle weakness
Likewise, if your muscles aren’t getting enough oxygen from red blood cells, they might feel like mush. So if that grocery bag feels like a million pounds, being low in B12 may be to blame.
“My job is very demanding, so I kept thinking that maybe my body is just tired—maybe I’m not eating right,” says Chantal Mossess, 31. “But 6 months ago I learned that my weakness and sluggishness was caused by not having enough B12.”
Tingling and numbness
Vitamin B12 deficiency can cause a number of strange sensations, like numbness, tingling, and more. “It felt like electricity was running from my head to my feet,” says Melanie Karmazin, 44, who was eventually diagnosed with a B12 deficiency. Others report a “pins and needles” sensation, and research backs this up.
These pains are all a result of nerve damage. And since vitamin B12 helps your nervous system function properly, they may signal you’re low in the nutrient.
Brain fog
Maybe you put your keys in the fridge—or had to think hard to remember your niece’s name. You might be worried about early-onset dementia, but sometimes low B12 may be to blame. The nutrient is crucial for maintaining healthy brain function, and being deficient can cause you to feel confused or forgetful.
“I’ve seen this deficiency mistaken for Alzheimer’s in elderly patients,” says Cimperman. “But once they have a blood test and it reveals a B12 deficiency, they start taking a supplement and their symptoms start to fade.”
Loss of balance
Feeling wobbly or dizzy is another common symptom of B12 deficiency, because being low in the nutrient may lead to nerve damage, causing you to lose your balance, feel less coordinated, or experience vertigo, research suggests.
Pale skin
If your complexion starts looking pale or yellow, low B12 may be the culprit. The vitamin helps with red blood cell production. So when you’re deficient in it, the red blood cells you do have are very fragile. When they break, they release bilirubin—a yellow pigment that makes your skin look jaundiced.
Smooth, red tongue
About half of the people with a severe B12 deficiency lose the papillae—or little bumps—on their tongues, especially around the edges. And since most of those papillae contain taste buds, you might lose the ability to taste your favorite foods, too.
“Women with a B12 deficiency may actually lose weight because food doesn’t taste as good to them anymore,” says Angela Grassi, R.D., a dietitian at the PCOS Nutrition Center. Some patients also complain of burning and soreness, particularly on the back of the tongue.
Anxiety and depression
Do you feel more down or anxious than ever? “A lack of B12 wreaks havoc on your mood, possibly leading to depression or anxiety,” says Grassi.
Doctors aren’t sure why being low in B12 increases your risk for depression. But it may have something to do with the fact that B12 helps synthesize brain chemicals, like serotonin and dopamine, that help regulate your mood.
Change in vision
In extreme cases, a lack of B12 may damage the optic nerve or plug up the blood vessels in the retina, causing blurry vision, double vision, sensitivity to light, and even vision loss, research finds. Regardless of a potential nutrient deficiency, contact your doctor right away if you experience any sudden changes in vision.
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