Chronic vitamin B12 deficiency can lead to many brain and neurological disorders. Learn why 40% of adults have low B12 levels and what you can do about it.
If you’re struggling with brain fog, memory loss, or fatigue, you may have a vitamin B12 deficiency.
The benefits of vitamin B12 (cobalamin) are numerous.
It’s essential for healthy nerve cells, red blood cell formation, energy, and DNA synthesis, to name a few. (1)
It’s found in everyday foods, yet is still one of the most common vitamin deficiencies, affecting 40% of all adults. (2)
Yet few people know they have it and doctors rarely test for it.
It can mimic many other conditions, including Alzheimer’s. (3)
Left untreated, it can cause a host of serious brain and neurological problems.
It’s time to remove any mystery surrounding this essential nutrient.
Let’s examine vitamin B12 deficiency signs and symptoms, the reasons why many people don’t get enough of this vitamin from their diet, dangerous myths about B12 food sources, and why vitamin B12 is so important for your brain.
Symptoms of Vitamin B12 Deficiency
Vitamin B12 deficiency is nothing to be taken lightly.
What level constitutes a deficiency is poorly defined, so symptoms can occur even in someone with a “normal” B12 level. (4)
Vitamin B12 deficiency symptoms can show up in your body as pernicious anemia, weakness, loss of appetite, constipation, numbness or tingling in the arms and legs, difficulty maintaining balance, and shortness of breath. (5, 6)
Signs of B12 deficiency can also affect your brain and your mind, manifesting as brain fog, memory loss, depression, anxiety, confusion, disorientation, hallucinations, or schizophrenia. (7, 8)
Eventually, long-term B12 deficiency can lead to permanent nerve and brain damage, brain atrophy, dementia and Alzheimer’s. (9, 10, 11, 12)
Vitamin B12 Food Sources
The simple answer to most vitamin deficiencies is to include more vitamin-rich foods in your diet.
Vitamin B12 foods are not hard to come by.
B12 is found in animal foods of all kinds — meat, poultry, pork, fish, seafood, dairy, and eggs.
The two best sources of B12 by far are clams and liver which contain 60 times more vitamin B12 than beef and over 100 times more than eggs. (13)
But for people who don’t eat animal products getting B12 is a very real problem.
And unfortunately, there’s a big dietary myth that’s causing a lot of people real harm.
Plant Sources of B12: A Dangerous Myth
Interestingly, the only life forms that can manufacture vitamin B12 are bacteria. (14)
Seaweed, algae, fermented soy products, and brewer’s yeast are purported to be plant sources of vitamin B12. (15)
But this is a dangerous myth.
There are no plant sources of true vitamin B12.
At one time, traditionally fermented soy products like miso and tempeh did contain B12, but no longer are a reliable source due to processing methods. (16)
Plant foods contain B12 analogs which are similar but not the same as vitamin B12.
By binding with B12 receptors, these pseudovitamins block your intake of true B12. (17, 18)
So consuming these B12 analog-containing foods can make a B12 deficiency even worse!
Some vegetarians, and especially vegans, take brewer’s yeast believing it is a vegetable food source of B12.
Yeast-based products like Marmite and Red Star Nutritional Yeast are often held up as the ultimate vegetable sources of B12.
But nutritional yeast does not naturally contain B12 — it is fortified with B12. (19, 20, 21)
This makes it no different than taking a supplement.
If You’re a Vegetarian
Almost half of lacto-ovo vegetarians and over 90% of vegans are B12 deficient. (22, 23)
If you’re a vegetarian, we recommend that you get your B12 levels checked to know where you stand.
If you’re a vegan, there’s no way around it. You need supplemental B12.
If you still aren’t convinced, I urge you to visit VeganHealth.org where you’ll find a wealth of information about B12 and the vegan diet.
Or pick up a copy of the book Vegan for Life.
Underlying Causes of B12 Deficiency
You’re at increased risk for B12 deficiency if you: (24, 25, 26)
- are a vegetarian or vegan
- are age 60 or over
- take acid suppressing drugs
- take metformin for diabetes
- have a chronic digestive disorder such as Crohn’s, celiac disease or irritable bowel syndrome
- have an eating disorder
- have had weight loss surgery
- abuse alcohol
- drink more than 4 cups of coffee per day
- are HIV positive
- have H. pylori, the bacteria that causes ulcers
Malabsorption — the Common Thread
The solution for vitamin B12 deficiency is not as straightforward as just eating more vitamin B12 foods.
Most people have plenty of vitamin B12 in their diets. (27)
It’s their vitamin B12 absorption that’s the problem.
Here’s why this is such a common problem.
The vitamin B12 found in food is bound to protein.
It gets released when hydrochloric acid and gastric protease in the stomach break this bond. (28)
An estimated 10-30% of adults over the age of 50 have difficulty absorbing vitamin B12 from food. (29)
Lack of Intrinsic Factor
Vitamin B12 deficiency can also be caused by a lack of intrinsic factor, a protein secreted by the stomach lining that binds to vitamin B12 and enables its absorption. (30)
Lack of intrinsic factor can be caused by weakened stomach lining or certain autoimmune diseases. (31)
This can lead to pernicious anemia, a decrease in red blood cells that occurs when the intestines cannot properly absorb vitamin B12.
If left untreated, it ultimately leads to serious neurological damage.
Treatment usually involves monthly B12 shots.
Vitamin B12 Interactions with Medications
There are several classes of medications that interfere with vitamin B12 absorption.
Here are two of the most common.
Proton pump inhibitors (PPIs) like Nexium, Prevacid and Prilosec and histamine 2 receptor antagonists (H2RAs) like Pepcid, Tagamet and Zantac are popular for acid indigestion, acid reflux, GERD, heartburn, and ulcers. (32, 33)
They are also strongly associated with vitamin B12 deficiency. (34)
People who regularly take these medications lack adequate Diabetes Medications
Metformin is a very popular drug for treating type 2 diabetes.
Research has found that 40% of patients using metformin have a vitamin B12 deficiency or were in the low-normal range. (36)
77% of metformin users with vitamin B12 deficiency also had peripheral neuropathy, a common form of nerve damage associated with type 2 diabetes.
Other medications that reduce levels of B12 in the body include anti-seizure medications and chemotherapy drugs. (37)
What to Look for in a Vitamin B12 Supplement
It’s always preferable to get as much of your vitamin needs met through your diet rather than supplements, but for some, vitamin B12 might be an exception.
For those with compromised digestive systems, supplemental B12 is better absorbed than from food where it’s bound to protein. (38)
And for some, the ability to absorb vitamin B12 from dietary supplements is limited by how much intrinsic factor is present.
B12 Supplement Options
There are a lot of choices when looking to buy a B12 supplement.
Besides being available in the usual tablets, capsules, and liquid drops, vitamin B12 is also available in sublingual tablets, sprays, or lozenges.
This latter group is marketed as being more bioavailable, but studies have not found this to be the case. (39, 40)
And as with any supplement, not all B12 supplements are created equal.
Low quality supplements usually contain cyanocobalamin.
This form of B12 is not well absorbed and actually produces a small amount of cyanide in the body. (41)
The highest quality forms of vitamin B12 are methylcobalamin or adenosylcobalamin. (42)
Vitamin B12 Shots
Anyone at risk for vitamin B12 deficiency should get their blood levels tested.
You can see your doctor or you can purchase a vitamin B12 test from an online lab like True Health Labs.
If your levels are very low your doctor may want to give you vitamin B12 shots to bring your levels up quickly.
Surprisingly little vitamin B12 is utilized from supplements.
Only about 10 mcg of a 500 mcg oral supplement dose is actually absorbed in healthy people. (43)
Those with pernicious anemia, permanent nerve damage, or ongoing digestive problems like Crohn’s disease may need to get regular B12 shots.
An interesting alternative to shots is vitamin B12 patches which supposedly overcome the malabsorption issue.
I’ve not seen any studies done on these but anecdotal evidence seems promising.
Vitamin B12 Supplements for Treating Dementia
The signs of dementia and Alzheimer’s are very similar to those of an advanced B12 deficiency. (44)
Some people diagnosed with these brain disorders make remarkable recoveries when their low B12 levels are addressed.
Some researchers believe that seniors with dementia, depression, and mood disorders should have their B12 levels closely monitored for life.
Both vitamin B12 shots and high doses of oral supplements have proven effective for treating seniors with these brain disorders. (45)
Vitamin B12 Deficiency: The Bottom Line
Vitamin B12 deficiency is a common and serious concern.
This deficiency can start with mild symptoms like fatigue and brain fog.
If left untreated, it can eventually develop into irreversible nerve and brain damage.
Eating plenty of foods that contain B12 a critical first step.
But it isn’t always enough.
The root cause of a B12 deficiency can be your body’s ability to absorb it.
If you exhibit any of the typical signs of B12 deficiency, don’t take chances.
Get your blood levels tested.
Rule out any underlying health conditions or medications that could be causing a deficiency.
Start taking a quality B12 supplement or see your doctor about B12 shots.
B12 deficiency symptoms in seniors are very similar to some of the symptoms seen in dementia and Alzheimer’s.
If someone you care about is dealing with one of these brain disorders, make sure their doctor monitors their B12 levels regularly.