6 Surprising Causes Of Vitamin B12 Deficiency

Vitamin B12 plays a huge role in a ton of body processes, so it’s crucial that we get enough. The issue is, all sorts of health and lifestyle factors can affect our levels—and even cause deficiency. Here’s what you need to know about the sneaky culprits stealing your B12, and how to get your levels back on track.

B12 Background

Like the other B vitamins, vitamin B12 helps your body convert food into energy. And we’re not just talking about ‘drank-a-giant-coffee’ energy here.

“B12 helps fuel the mitochondria inside our cells, which produce cellular energy,” explains Robin Foroutan, R.D.N., a specialist in integrative medicine and spokesperson for the Academy of Nutrition and Dietetics. “From healing wounds to making sure that your metabolism is working properly, everything that your body does requires that energy.”

B12 also helps your body produce DNA and red blood cells, contributes to the way nerve cells in the brain communicate with each other, and plays a role in mood, immune function, and cardiovascular health, too.

B12 Deficiency

We can only get B12 from our diet or supplements. “B12 is found in red meat, organ meat, seafood and shellfish, nutritional yeast, chlorella, and spirulina,” says Foroutan.

According to Adam Perlman, M.D., an integrative health and well-being expert at Duke University, vitamin B12 deficiency affects between 1.5 and 15 percent of people in the U.S. Since the richest sources of B12 are animal proteins, vegetarians and vegans may be at a much greater risk for deficiency.

B12 plays many roles in the body, so a deficiency can reveal itself in a number of different ways. “Fatigue is a big one,” says Foroutan. “Muscle fatigue, full-body fatigue, brain fog, and difficulty concentrating are all major symptoms, because you’re just not able to make as much cellular energy as you otherwise would.” Depression, anxiety, anemia, and numbness and tingling can also occur as a result of deficiency.

Long-term, vitamin B12 deficiency can contribute to dementia and an increased risk for stroke, heart disease, Alzheimer’s disease, and even certain cancers.

If you’re experiencing any of the following symptoms of B12 deficiency, talk to your doc about doing a blood test to check your levels.

1. You Have Low Stomach Acid

“The first step of B12 absorption happens in the stomach and requires stomach acid,” says Foroutan. “So if you don’t have enough stomach acid, you don’t absorb much B12.” Often, low stomach acid is marked by indigestion and bloating.

Some of the most common stomach acid suppressors: medications specifically designed to do just that. First are heartburn meds called proton pump inhibitors (PPIs), like Nexium and Prilosec. Then, histamine 2 receptor antagonists (H2RAs), like Pepcid and Zantac. Research shows that these acid inhibitors directly lead to malabsorption of B12.

“Anybody who’s on an acid blocker is at very high risk for B12 deficiency, and would likely need to take a supplement or even get B12 shots depending on their blood levels,” says Foroutan.

Low stomach acid, a condition called hypochlorhydria or achlorhydria, can also be caused by chronic stress, aging, and consumption of processed foods and refined sugars.

2. You’re On Birth Control

Because of the way the body metabolizes birth control, taking it comes with the inconvenient side effect of depleting your body’s B vitamin stores—especially folate, riboflavin, vitamin B6, and B12, says Foroutan. In fact, research has linked taking higher-estrogen birth control pills and a greater chance of B12 deficiency.

Though other studies have identified sharp decreases in women’s B12 levels after starting birth control pills, actual deficiency seems to be uncommon—even after three years of taking birth control. “Most women taking birth control wouldn’t need to have their B12 measured regularly,” says Perlman.

However, if you’ve been on birth control for a while and are experiencing any symptoms of B12 deficiency, consider talking to your doctor about testing your levels and adjusting your prescription or adding a supplement. “If you’re taking birth control, you should also probably be taking a really good quality B complex with a lot of B12 in it,” says Foroutan.

3. You’re On Metformin

Metformin, a medication initially developed to treat type 2 diabetes and now sometimes used as a weight loss aid, is one of the most prescribed drugs out there. “Metformin works to lower the amount of sugar in the blood of people with diabetes,” explains Perlman. “It does this by decreasing the amount of sugar produced in the liver and increasing the sensitivity of muscle cells to insulin.”

Despite Metformin’s popularity, long-term use has been linked to decreased levels of B12, according to a study published in the Journal of Clinical Endocrinology & Metabolism.

Interestingly, other studies have linked B12 deficiency to insulin resistance, which can lead higher insulin levels, higher blood sugar levels, even type 2 diabetes, and weight problems—all of the issues Metformin itself is used to address!

If you take Metformin, Perlman recommends eating a diet rich in B12-containing foods, like eggs, sardines, beef, and tuna.

4. You Have A Gut Condition

Digestive conditions like colitis, Crohn’s disease, inflammatory bowel disease, leaky gut syndrome, and celiac disease can all tank your B12 levels. “Any kind of disturbance in the digestive tract can really influence how well you can absorb B12,” says Foroutan. “And with any of these conditions, there are major digestive and absorption disturbances going on.”

Related: The Term ‘Leaky Gut’ Is All Over The Internet—But What Exactly Is It?

If you’re suffering from any of the above digestive issues and experiencing decreased vitamin absorption, vitamin B12 shots can help up your levels.

5. You Have a Parasite

Scary as they may sound, intestinal parasites are much more common than you think. “In fact, it’s normal to have some parasites,” says Foroutan.

However, parasites like tapeworms or giardia can prevent your body from absorbing the B12 it needs. According to research published in the Cleveland Clinic Journal of Medicine, up to 40 percent of people infected with D latum—a tapeworm acquired by ingesting under-cooked or raw fish—develop low levels of vitamin B12. So if you’re a sushi addict, proceed with caution.

If you have a parasite, a slew of gastrointestinal symptoms will likely let you know. “Stomach pain, diarrhea, sudden unexplained weight loss, excess bloat and/or gas, and fever are a few telltale signs,” says Perlman. If you’re experiencing these issues with no other explanation, make an appointment with your primary care doctor or a gastroenterologist ASAP.

6. You Drink Too Much

“When your body has to process alcohol, it requires a lot of nutrients, including B vitamins, which can lead to deficiencies or insufficiencies if you’re using a lot of nutrients to metabolize alcohol and not getting enough through food and supplements,” says Foroutan.

Not only does drinking a ton wreak havoc on your liver (your detox center), but it also irritates your stomach (a condition called gastritis), which can lower stomach acid production and decrease your ability to absorb B12, says Foroutan.

The solution is obvious here: Stick to the recommended guidelines for alcohol intake. That’s no more than two drinks a day for men and one for women.

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