Posts from September 28, 2026

How do you get B12 deficiency?

B12 is hard to absorb: Before it's in your cells, a lot can go wrong.

Low B12 can occur from eating little animal food, which is common these days, but also from eating predominantly carbohydrates at every meal: the standard Western diet. This creates an upper fermenting gut, SIBO, and irritable bowel syndrome. Your small intestine should be nearly sterile, but yeast, bacteria, and parasites live happily there, consuming your vitamins and minerals.

That is why people who start a ketogenic diet often see a great improvement in energy and overall well-being. Eliminating grains and dairy can also help, and some people eliminate down to only meat for a while to give themselves a "clean slate" and restore normal gut function.

Another major cause of low B12 is autoimmune disease (such as thyroid disorders, Type 1 Diabetes, Celiac, and Crohn's) or stomach issues. Like an upper fermenting gut, these lead to malabsorption. Many patients are simply told by their doctor that they have "irritable bowel".

Even in children, B12 deficiency can be seen. You can also be born with genetic variations that affect methylation, such as the MTHFR gene, which is present in around 40% of people, or other hereditary errors in B12 metabolism. Always avoid synthetic folic acid from fortified foods and choose methylfolate or folinic acid instead, as synthetic folic acid is added to flour and grains in many countries.

Furthermore, B12 deficiency can be triggered by medications, such as the birth control pill, antacids, metformin, certain antibiotics, and anti-epileptic drugs or by stomach reduction surgery. Laughing gas (nitrous oxide) inactivates B12 in your cells; while known as a party drug, it is also frequently used in dentistry and labor. Finally, cancer treatments can cause low B12 levels, whereas maintaining good B12 levels can greatly improve outcomes, as B12 is essential for making DNA and RNA.

More articles about vitamin B12