Skip to content

B12 and Mental Health: It’s Not All in Your Head

The B12 Mental Health Connection It's Not All in Your Head

We all want to live healthier, happier and more fulfilled lives. To be the best versions of ourselves. But how can we if we feel tired, anxious or depressed – using our last bit of energy to try to feel “normal”?!

In America — land of the free, home of the brave, and the B12 deficient — over 40% of the adult population has a B12 deficiency or at the very least, subnormal levels of the vitamin. That number would increase significantly if you take into consideration that people in the US are only declared deficient if their B12 levels drop below 200 pg/ml (145pM). In Japan, however, someone would be declared deficient if their levels dropped below 550 pg/ml (400pM). Most experts on the subject agree with the Japanese on this, primarily because the tests aren’t that accurate (more on this later).

With nearly half of the population experiencing this deficiency, it’s likely that you have it too.

The Mental Health/B12 Link

If you’ve been following my work, you know I’m beyond obsessed with three things: gut health, mental health, and the link between them.

We have to get to a point where, as a population and as medical practitioners, we realize that many diseases are symptoms of an underlying nutritional deficiency.

When you replete the body with the nutrition that’s lacking, the body can begin to return to optimal function. Or in other words: when you give your body the right kind of fuel, it actually works like it’s supposed to. In other words, you can actually get your mental and physical health back by supporting your body with what it needs versus covering the symptoms of deficiencies with drugs*

B12 deficiencies are often a root cause of neurological, psychiatric and cognitive issues. Having a B12 deficiency puts you at risk for developing depression and anxiety, fatigue, and can worsen hypothyroid and other health concerns.

Why Is B12 Important?

Vitamin B12, also known as cobalamin, plays an important role in the synthesis of the DNA in our cells. It is one of the largest and most complex vitamin molecules and the only one with the trace element cobalt. It’s fundamental in maintaining the nervous system and is involved hemoglobin production. Folks with low B12 levels are also more likely to have several forms of neurological decline, like dementia, since the brain needs B12 in constant supply to stay healthy. Life without vitamin B12 is literally impossible.

Symptoms of Vitamin B12 Deficiency You Need To Know

As you’ve gathered from the title, vitamin B12 deficiency could be one of the root causes of your anxiety and depression. However, other symptoms of low B12 can make you feel crappy at the very least, and at their worst leave you hospitalized or bedridden (intense, right?) These include:

  • Dizziness
  • Fatigue
  • Memory loss and dementia
  • Confusion, particularly in the elderly
  • Nerve pain
  • Irritability
  • Mood disorders
  • Difficulty concentrating
  • Cognitive impairment
  • Shortness of breath
  • Nerve demyelination
  • Growth failure and brain injuries in babies
  • Tremors
  • Brain Atrophy

Looking back on my days as a hospice nurse, I wonder how many of my patients had B12 deficiencies and could have gotten significant relief from a simple supplement.

Instead, what I saw then and see now in my current Functional Medicine patients is the use of pharmaceuticals to treat what I often think are B12 deficiency signs. Furthermore, what most of these drugs do to “treat” symptoms is mask them, while the root cause (B12 deficiency) ravages on. The longer you remain B12 deficient the worse you’ll get. What’s particularly worrying is that in some of the most severe cases the damage caused by a lack of B12 is irreversible.

Vitamin B12 Etiology – Are You At Risk?

Not everyone can attribute their depression and anxiety to vitamin B12. However, there are some groups that have a higher chance of developing a deficiency.

Vegan or Vegetarian Diets

Vitamin B12 is naturally found in animal products. Though B12 can also be found in fortified foods, that B12 is often of poor quality and is less absorbable. Since the only natural sources are animal products, strict vegetarians and vegans are at risk of developing a deficiency as they’re not ingesting any animal derived food. When you first transition to a vegan or vegetarian diet you may not experience any vitamin B12 deficiency symptoms. Your body naturally stores B12 and that supply can last for up to 4 years.

Diet Lacking in Real Whole Foods

The old adage applies here for sure: you are what you eat, and what you put in is what you get out. We know that certain foods support a healthy and balanced mood and others can tank your mood and energy pretty quickly. Gluten, dairy, sugar, caffeine, alcohol – these are all foods that are linked to increased inflammation, and thus, linked to increased anxiety, depression, insomnia and other mood issues.

While B12 may come from animal products, you’re not going to get the quality you want from GMO, antibiotic, hormone laden, factory-farmed animal foods. Food needs to be in its most natural state to provide your body with adequate amounts of the right kinds of B12.

Treating Heartburn Using Acid Reducing Drugs

People with chronic heartburn (also known as GERD or reflux) are likely to start using PPIs (proton pump inhibitors) or H2 blockers (histamine 2 receptor antagonists), drugs like omeprazole, Pepcid, Zantac, Prilosec, Protonix, to suppress the secretion of stomach or gastric acid. However, gastric acid plays an important role in digestion and absorption. Inhibiting it can make absorbing B12 difficult which of course leads to deficiency.

Intrinsic Factor

Nutrient absorption starts in the mouth and continues in the stomach followed by the small intestine. Vitamin B12 is no different. The absorption of vitamin B12 begins with a protein secreted by your stomach called intrinsic factor. Intrinsic factor breaks up the vitamin B12 in your food and binds with it so your small intestine is is able to absorb the B12 easily (at the terminal ileum).


Methylenetetrahydrofolate reductase enzyme deficiency (MTHFR) is a genetic mutation. It impacts how your body deals with folate or folic acid. Folate is necessary in the absorption of Vitamin B12, if you don’t have the enough folate in your body your B12 levels will naturally decrease.

Small Intestine Bacterial Overgrowth (SIBO)

Your gut, specifically your large intestine, is (hopefully) full of good bacteria, which helps you absorb what you need to and maintains the health of your gut and your whole body. But too much of a good thing is bad, and that’s certainly the case when you have an overgrowth of good bacteria in the Small Intestine – where they don’t belong. If you’re suffering from SIBO (Small Intestine Bacterial Overgrowth,) your body is unable to absorb the B12, even if it’s been bound to the intrinsic factor.

If you’re having digestive symptoms and chronic low B12, it’s time to get your gut checked for sure with a Functional Medicine provider. I would recommend both a stool test and a SIBO breath test.

But What If My B12 Levels Are Normal?

Okay, so you’ve suspected that you could be B12 deficient and as a result headed straight to your doctor to get tested. Or perhaps you just want to be extra cautious because you’re part of the “higher risk” groups. If your test comes back “normal” or “fine,” but you don’t feel “normal” or “fine,” now what?

Blood tests can produce misleading results.

The test most commonly used to determine B12 levels is the serum test. This test isn’t always as accurate in conclusively determining your B12 levels. Although it can be useful in discovering really deficient levels, it may not be as effective if the overall B12 in your system hasn’t dropped below 200 pg/ml – which is already dangerously low.

What the serum test takes into account is all the B12 in your bloodstream. This includes inactive B12 analogues in addition to B12 that has been bonded to proteins like haptocorrin. This kind of “inactive” B12 can make your test levels appear high, but really the amount of active B12 that’s available for your cells to use could be far lower.

I always order serum B12, MMA (methylmalonic acid) and look at the MCV – a part of your CBC to get a more holistic picture of your B12 supply. That said, I treat humans, not labs. If you feel tired or fatigued and your lifestyle is on point, I’ll start a trial of B12 to see if it helps – it almost always does!

Western Medicine generally does treat labs, not people.

I was a primary care provider for a many years. The sad fact is that most western primary care providers treat the labs, not the person in front of them. This is changing, slowly, but it’s the sad norm. This often means that B12 deficiencies go untreated, even in folks with long standing depression and anxiety, often for years.

We should also remember that western medicine is focused on keeping you from dying right now, which is great when that’s what you need. But what that system isn’t great at is chronic medical care or enhancing and supporting health on a deeper level. No dis to western medicine, it’s the care I want for a gunshot wound or heart attack for sure, but day after day in my Functional Medicine practice, I review the labs of exhausted, depressed, anxious people with B12 levels in the 200s and 300s whose primary care told them not to worry about it. I want to urge you to not listen to that advice and to find a holistic, naturopathic or Functional Medicine provider to give you a second opinion.

If you don’t feel well, something isn’t right.

Not to insult your physicians capabilities in any way, but your doctor doesn’t know your body better than you, and your PCP may not recognize the symptoms of a vitamin B12 deficiency. Remember that your PCP, even the best PCP in the world, is not reading your labs in a holistic or Functional Medicine way if that’s not how they practice. I want to encourage you to always listen to your body. If you’re still experiencing symptoms and you’re not getting anywhere with the help of your PCP or a specialist, try increasing your B12 rich food intake, and again, get a second opinion.

The body only absorbs as much B12 as it needs, the remaining B12 is stored in your liver up to 2000 to 4000 µg. Whatever isn’t stored is simply flushed out in your urine. There haven’t been any reports of higher than usual B12 negatively affecting most people*.

That said, please consult your healthcare team before starting any supplements or treatments! There are some folks, like those with megaloblastic anemia, hemochromatosis and hemochromatosis should not take B12 because of the risk of iron overdose. Folks with Leber’s disease (an inherited eye disorder) should watch their dietary intake of B12 and should not supplement with it because it can worsen their disease. Some folks with slowed detox can feel too hyper or revved up on B12 and should reduce their dose and see their healthcare provider.

When your health (especially your mental health) is at stake why take the risk of having an untreated B12 deficiency? Healing the root cause of your depression is what will help you blossom into the person you want to be. Your mood, mind and body will thank you for it.

*The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this Website.

I hope you found this information helpful! I am currently focused on helping women to optimize their wellness through life coaching, and no longer provide Functional Medicine consultations with lab work, supplements, etc. Instead, I help women to regulate their nervous systems and manage their thinking and mindset, which is vital root cause medicine. You can learn more about this approach by listening to these episodes: polyvagal theory, leaky gut, and the nervous system.
To learn more about how we can work together, please see
Please do not email to ask if I can see you as a patient, and instead use the directory at to find a Functional Medicine provider who is doing laboratory-based clinic work.
Thank you!


  1. marta on March 16, 2020 at 12:20 pm

    Genial!!!!!!!!!!!!!!!!!!!!!!!!!!! Gracias!!!!

    • Victoria Albina on March 16, 2020 at 8:37 pm

      Mi placer!

  2. Tapiwa Chimbiri on September 21, 2020 at 5:29 pm

    My wife is having mood swings and hallucinations due to this. When she get 1ml B12 injected she is ok during the day then at night it just starts again. I don’t know to help her what’s the alternative medicine?

    • Victoria Albina on September 21, 2020 at 6:13 pm

      Hi Tapiwa,

      Gosh, I’ve never heard of that happening and I’m sorry that happened for your wife. I don’t give individual medical advice through blog comments, and would encourage you all to visit a licensed Functional medicine provider for support and have them look into methylation, lyme, and mold in addition to their standard work up. Could also be secondary to something in the kind of B12 shots she got…?

      And of course I would advise against taking anything that gives you adverse side effects!

      All the best!