Tuesday, November 18, 2025
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HomeHealthB12 deficiency can be deadly: Why Dr Greger says vegans must supplement

B12 deficiency can be deadly: Why Dr Greger says vegans must supplement

Vitamin B12 supplementation is essential for people following plant-based diets, warns Dr Michael Greger from Nutritionfacts.org. This week, he released the first in a series of five videos on the subject, noting there are no consensus clinical guidelines on preventing, diagnosing, and treating B12 deficiency.

B12 deficiency can cause a wide array of health problems, impacting the brain, nerves, muscles, and overall mental state, potentially leading to severe conditions like psychosis and even death in infants, he says.

The lack of accepted clinical guidelines, he explained, made informed decisions in the treatment of B12 deficiency “challenging.”

Bariatric surgery studies show that B12 absorption issues can lead to metabolic impairments within months, indicating that liver stores might not provide sufficient long-term B12 levels.

A case study he highlights in his first video demonstrates that even with normal blood B12 levels, homocysteine can increase significantly without continuous supplementation, underscoring the crucial need for B12 intake on unfortified plant-based diets.

He also noted an interaction with folate. A drop in folate levels can complicate B12 deficiency, as both vitamins play a role in homocysteine detoxification.

For vegans, a B12 check should form part of an annual visit to your GP. An annual blood test is considered essential because deficiency symptoms are varied and can differ between patients. 

“The vitamin is necessary for the synthesis of DNA, so, a deficiency in B12 can cause pretty much anything,” Dr Greger says.

These could include brain, psychiatric, sensory, constitutional, muscle, and nerve problems.

More specifically, B12 deficiency can manifest as clotting and bleeding disorders, catatonia, hallucinations, psychosis, and even suicidal thoughts. In infants, severe B12 deficiency can lead to coma, respiratory failure, and severe brain damage.

It’s also important to note that a functional B12 deficiency can cause impaired metabolism and a rise in methylmalonic acid and homocysteine levels.

WFL
WFLhttp://wholefoodliving.life
Whole Food Living reviews and selects material from a wide variety of international sources. Our primary focus covers food, health and environment. We publish fact checked official announcements made as the result of formal studies conducted by Universities, respected health care organisations, journals, and scientists around the globe.
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