Nutrition / Food

How Do I Know If I’m B12 Deficient?

Our bodies need B12 to function. Here's how to make sure you're getting enough of it.

If you’ve been told by your doctor that you have a B12 deficiency, you’re not alone. B12 deficiencies are a lot more common than people realize, says Nishta Saxena, a registered dietitian and founder of Vibrant Nutrition, estimating that it’s North America’s second most common deficiency after iron. So, what should you do if you find out that you’re B12 deficient, or have a hunch that you might be? Here, we asked experts why the body needs B12, and what to eat to make sure that your diet is B12-rich.

What is B12, and why do we need it?

B12 is a critical vitamin for our health. It’s necessary for many bodily processes, and it’s how we extract energy from food, says Saxena. “It’s used primarily in energy metabolism, making red blood cells, protecting and creating nerves, and has functions in terms of protecting DNA,” Saxena says. “When we want to eat food, make energy, and get those molecules called ATP that we use for energy, we really require B12 to do that,” she adds.

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What are symptoms of a B12 deficiency?

“One of the first things people will notice is numbness and tingling in their hands and feet,” Saxena says. Feeling fatigued, physically weak, and having issues with balance may also indicate a B12 deficiency.

“Some people can have a change in their ability to think clearly,”  Saxena says. “They’ll say [that] they feel foggy or have a hard time thinking critically or making decisions. They can even have trouble with memory.”

Emily Tam, a registered dietitian and nutritionist, points out that B12 plays a vital role in the health of our red blood and nerve cells. Due to this, deficiency can result in anemia and problems within the nervous system. In serious cases, Tam says that if a B12 deficiency is not treated in a timely manner, it can “lead to cognitive impairments and irreversible nerve damage.”

If you think that you have a B12 deficiency, it’s important to visit your doctor and get bloodwork done. According to the National Institutes of Health, values below approximately 170-250 pg/mL (120-180 picomol/L) indicate a B12 deficiency for adults. But, as Saxena points out, some people can fall within a healthy range and still experience deficiency symptoms. So it’s important to talk to your health care provider to develop an appropriate treatment plan.

What foods are rich in B12?

Rachel Caven, a nutritionist and clinic director at Caven Nutrition, says that “B12 is mainly found in animal products, such as liver, sardines, trout, salmon, meat, eggs, and cheese.” Tam adds that “organ meats and mollusks, such as clams and mussels, are especially rich in B12.”

If you’re a vegetarian, Tam says various plant-based foods that are fortified with B12 are good options. For example, non-dairy milks, meat analogs, energy bars, and nutritional yeast. “Check nutrition labels, though, as not all brands are fortified,” Tam cautions.

What causes a B12 deficiency?

Caven says a B12 deficiency can be caused by a diet that lacks B12-rich food. This is typically more common in vegetarian and vegan diets, Carven says. People who don’t eat meat need to ensure that they consume enough other foods high in B12.

Outside of diet, Tam says that someone can develop a B12 deficiency even if their lifestyle isn’t the culprit. “People who don’t produce adequate amounts of stomach acid or intrinsic factor have reduced access to the B12 in food,” she says, pointing out that this is most common in older adults and people with pernicious anemia, a condition that prevents you from absorbing healthy amounts of B12 from food.

“Stomach acid and intrinsic factor, both of which are secreted by cells in the stomach, are needed to extract the B12 bound to food and make it available for absorption,” she explains. “Health conditions that affect the intestinal tract where B12 is absorbed—like celiac disease and Crohn’s disease—can also lead to deficiency.”

Finally, Saxena says an unhealthy lifestyle—including poor diet and binge drinking—can make B12 absorption much harder. “If you’re living a really toxic lifestyle, the liver is required to do a lot of detoxification. That can use up B12 stores really quickly,” she explains. “If you’re not eating well and you have a toxic [living] pattern, B12 gets used up [and] then you don’t have any left in your bloodstream.”

What can you do if you are B12 deficient?

If diet is the reason why you’re low on B12, it’s important to eat more B12-rich foods. But, if you increase your meat and fortified foods intake and are still experiencing a deficiency, you may benefit from B12 supplements.

“B12 deficiency can be effectively corrected with oral supplements. Seek guidance about the amount to take from your primary care provider or a dietitian or pharmacist,” Tam says.  “Whether you take supplements or get injections, eat well and aim for your diet to include reliable sources of B12.”

B12 shots are all the rage (thanks Gwyneth Paltrow and team Goop). However, Tam says it’s best to make sure you really need one before getting injected with the vitamin. She says that if you are deficient, B12 shots can help. But it’s important to talk to your health care provider beforehand. “The frequency of the treatments will depend on the severity and cause of the deficiency,” she says.

But, if you don’t need B12 shots, don’t get them. “As much as B12 shots have been touted in recent years as a weight loss aid and an energy booster, there isn’t a solid evidence base to support these claims,” Tam says. “If your B12 level is normal to begin with, getting shots likely won’t do anything for you.”

A B12 deficiency is nothing to ignore. If you suspect that you might be low on the vitamin, talk to your doctor about getting bloodwork done. Then, he or she will be able to properly treat your individual situation.

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