Vitamin B12 deficiency: The overlooked cause of psychiatric symptoms that mimic mental illness

09/16/2025 / By Evangelyn Rodriguez

A 57-year-old woman with severe psychiatric symptoms (depression, anxiety, hallucinations, catatonia) was successfully treated with vitamin B12 supplementation. Within two months, she returned to baseline health without needing psychiatric drugs.
Vitamin B12 deficiency mimics dementia, depression, psychosis and multiple sclerosis symptoms, and is often misdiagnosed and wrongfully treated with pharmaceuticals.
Having abnormally low vitamin B12 levels disrupts methylation (affects detox, gene expression) and elevates homocysteine (linked to depression, cognitive decline). Genetic variations (MTHFR) can cause functional deficiency even with “normal” serum B12 levels.
Common causes of vitamin B12 deficiency include low stomach acid, vegan or vegetarian diets, autoimmunity, gut damage and use of certain medications (metformin, acid blockers).
Solutions include diet changes, supplementation with active forms and injection therapy.

In 2003, a 57-year-old woman spent months undergoing antipsychotic medications, antidepressants and two rounds of electroconvulsive therapy (ECT) before doctors checked her vitamin B12 levels. Her symptoms — depression, anxiety, movement abnormalities, lethargy, hallucinations and catatonia — had escalated for years. Yet, within two months of vitamin B12 supplementation, she returned to her baseline health from 14 years prior, requiring no further psychiatric treatment.

This case, documented in a study published in Acta Psychiatrica Scandinavica, underscores a critical but often ignored reality: Nutritional deficiencies can mimic severe mental illness, leading to unnecessary and harmful pharmaceutical interventions. With up to 15 percent of the population deficient in vitamin B12, experts argue that routine screening for this vitamin should precede psychiatric diagnoses—yet it remains overlooked in mainstream medicine.

How vitamin B12 deficiency masquerades as mental illness

Vitamin B12 is essential for the synthesis of myelin, the protective sheath around nerves that ensures proper brain function. Vitamin B12 deficiency can lead to neurological symptoms resembling dementia, multiple sclerosis and psychiatric disorders, but its effects on mental health is even more profound. (Related: Vitamin B12 offers a promising natural solution for autism symptoms.)

Having low vitamin B12 levels can cause:

Depression and anxiety: Lack of sufficient vitamin B12 disrupts the production of neurotransmitters like serotonin and dopamine, which are falsely blamed as the sole causes of mood disorders.
Fatigue and lethargy: Vitamin B12 is crucial for red blood cell formation and energy metabolism; a deficiency can cause chronic exhaustion which can be misdiagnosed as clinical depression.
Psychosis and hallucinations: Severe vitamin B12 deficiency has been linked to paranoia, auditory hallucinations and even catatonia — symptoms often treated with antipsychotics instead of nutritional correction.

Hidden mechanisms: Methylation, homocysteine and genetic override

Vitamin B12’s role extends beyond basic nutrition. For instance, this nutrient governs methylation, a biochemical process critical for detoxification, hormone balance and gene expression. The consequences of vitamin B12 deficiency include:

Methylation dysfunction – Without vitamin B12, the body struggles to “tag” genes properly, impairing detox pathways and neurotransmitter synthesis.
Homocysteine buildup – Elevated homocysteine — a marker of vitamin B12 or folate (B9) deficiency — is linked to depression, cognitive decline and cardiovascular disease.
Genetic variations – Some individuals have mutations (like in the MTHFR gene) that impair vitamin B12 utilization, meaning standard blood tests may miss a functional deficiency.

Most doctors only look at serum vitamin B12 levels, but studies show this is unreliable because:

27 percent of depressed women show vitamin B12 deficiency markers despite having “normal” serum levels.
Patients with levels as high as 400 pg/mL still exhibit fatigue, depression and dementia — far above the traditional deficiency cutoff (150-200 pg/mL).
Folic acid fortification in processed foods masks vitamin B12 deficiency by correcting blood abnormalities without fixing neurological damage.

Causes of vitamin B12 deficiency

Here are the common causes of vitamin B12 deficiency:

Low stomach acid (Achlorhydria)

Acid-blocking medications (PPIs like Nexium) impair vitamin B12 absorption, with 12 percent of long-term users becoming deficient. Aging, chronic stress and poor diet exacerbate the problem.

Dietary restrictions

Vegans and vegetarians are at high risk of vitamin B12 deficiency since the vitamin is primarily found in animal products.

Autoimmunity and gut damage

Pernicious anemia (autoimmune destruction of stomach cells) blocks vitamin B12 absorption, while gluten and GMOs damage intestinal lining, reducing nutrient uptake.

Medications

Metformin, a common diabetes drug, depletes vitamin B12 — yet few patients are warned about this.

The solution: Diet and activated vitamin B12

Vitamin B12 is naturally present in a variety of foods. According to Brighteon.AI‘s Enoch engine, you can directly source vitamin B12 from beef liver, eggs, fish (such as salmon, herring and mackerel), dairy products (cheese, milk and yogurt) and organ meats. Fortified grains and plant-based milks also contain vitamin B12.

For vegans and vegetarians, studies show that dried green and purple lavers (a type of seaweed); fermented foods like tempeh and fermented black tea; edible mushrooms like black trumpet, golden chanterelle, lion’s mane and dried shiitake; and chlorella are excellent natural sources.

Instead of synthetic cyanocobalamin (which contains trace cyanide), individuals planning to supplement with vitamin B12 should opt for active forms like methylcobalamin or 5-deoxyadenosylcobalamin. Studies show:

Injections (1,000–5,000 micrograms, mcg weekly) work faster than oral supplements for severe deficiency. This should only be done with proper medical guidance.
Patients often see rapid improvements in mood, energy and cognition within weeks of treatment.

The clinical case mentioned above is not isolated. Numerous studies have linked vitamin B12 deficiency to psychiatric symptoms, among other health issues. Yet, instead of investigating root causes, doctors often prescribe antidepressants, antipsychotics or ECT, worsening the problem.

As health care becomes increasingly pharmaceutical-driven, cases like this underscore the need for personalized, root-cause medicine. Before labeling patients with lifelong mental illness, clinicians must ask: Could this just be a vitamin deficiency?

For millions suffering unnecessarily, the answer might be as simple as a vitamin B12 shot.

Watch the video below to learn how vitamin B12 can help children with autism.

This video is from the Daily Videos channel on Brighteon.com.