6 Early Signs of a Vitamin B12 Deficiency

Fatigue is one symptoms of low B12, and the deficiency becomes more common with age.
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Vitamin B12: It's one of the most essential vitamins for our bodies, and yet so few of us understand its impact. Licensed dietitian nutritionist Anthony Crifase calls the nutrient an all-star — and for good reason.


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B12 plays a role in a wide range of important functions, including nerve development, keeping red blood cells healthy and helping your body break down protein and fat.

People who eat meat tend to get plenty of B12, since its found in animal-based foods. Vegetarians or vegans may struggle to get enough, though, and many people may experience a deficiency as they take more laps around the sun.


"Like most vitamins, B12 is absorbed in the digestive system," Crifase says. "As we age, B12 levels tend to decline due to poor absorption."

For the same reason, people with gastrointestinal disorders like celiac or Crohn's disease and those who have had gastrointestinal surgery may not be able to absorb enough of the nutrient from food alone, according to the National Institutes of Health (NIH).



Ask your doctor about having your B12 level checked if you are a strict vegetarian, have had weight-loss surgery or have a condition that interferes with the absorption of food.

Here are some common early symptoms of a deficiency to look out for.

1. Fatigue or Feeling Weak

Even though you technically got plenty of shut-eye, you find yourself sitting at your desk with your eyelids drooping. If you're constantly tired and there's no obvious explanation, you may be dealing with a nutritional deficiency.


Crifase says fatigue is a key indicator of low B12 because it can compromise your circulatory system. In other words, your blood can't circulate oxygen the way it's supposed to, leaving you feeling less than 100 percent.

2. Confusion or Trouble Focusing

Feeling fuzzy or forgetful is another common sign of too-low B12 levels, according to Harvard Health Publishing. Some people experience memory loss, and others have trouble with thinking and reasoning.

3. Difficulty Walking or Balancing

Typically, you're the first one to volunteer for a 5K. Or, even if you're not exactly drinking the running Kool-Aid just yet, a flight of stairs isn't a big deal for you.

But if recently you feel like putting one foot in front of the other is a challenge, it may be related to your B12 levels, according to David Greuner, MD, a board-certified surgeon and co-founder of NYC Surgical Associates. If simply walking makes you feel unbalanced, your body could need more B12 to flow smoothly and effectively.

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4. Blurry Vision

When someone is suffering from a B12 deficiency, their nervous system is compromised, says family and emergency room doctor Janette Nesheiwat, MD. This is partly why they may struggle with balance or movement, and also why some people report blurred vision.

Because this is a lifestyle-altering symptom, it could be the reason many people finally make an appointment with their doctor to find a solution, Dr. Nesheiwat says.

5. Swollen or Sore Tongue

Vitamin B12 deficiency can cause issues in the mouth, too. In particular, it may cause the tongue to swell and feel sore, per the NIH. The tongue may also appear smooth and "beefy red," according to Stanford Medicine.

Keep in mind, though, that other things can cause these symptoms, too, including an infection, allergic reaction or even bad-fitting dentures, according to the U.S. National Library of Medicine.

6. Numbness or Tingling

Vitamin B12 helps maintain healthy nerve cells. If those cells aren't receiving the nutrients they need, an early sign may be numbness or a tingling sensation in your fingers or toes, according to Johns Hopkins Medicine.

It's important to determine if the cause of these symptoms is a B12 deficiency, because a severe case may cause brain damage.

How to Treat a Vitamin B12 Deficiency

If you think you might have a B12 deficiency, there's no harm in getting tested, especially since it's an easy process. Typically, it's diagnosed using a conventional blood test or methylmalonic acid (MMA) test, which are both fairly routine procedures.

More often than not, the issue can be resolved by making alterations to your diet, such as adding more B12-rich foods like fish, shellfish, eggs, red meat, poultry, dairy and fortified foods like some breakfast cereals.


The average adult should get about 2.4 micrograms of B12 daily, according to the NIH. Three ounces of salmon, tuna or trout will provide more than enough, and a cup of milk or low-fat yogurt will get you halfway there.

If a diet change isn't possible, a B12 deficiency can usually be resolved through supplements. A March 2018 study in the Cochrane Database of Systematic Reviews and a September 2017 study in American Family Physician showed that supplements between 1,000 and 2,000 micrograms are safe and effective ways to treat the problem. If your symptoms are particularly severe, you may also be prescribed high doses of this vitamin that should be injected rather than swallowed.