Vitamin B12 contributes to blood formation, nervous system functions, and DNA synthesis, but it is one of the most sensitive vitamins for absorption.
According to experts, it is not enough to eat meat, fish, eggs, or even take supplements for vitamin B12 to enter the bloodstream; it requires normal stomach acidity, an internal factor, and healthy intestines.
1- Intrinsic factor – one of the most significant obstacles to vitamin B12 absorption. Intrinsic factor is a special protein produced in the stomach that helps the vitamin absorb in the small intestine. If it is deficient or absent, vitamin B12 is lost from food, even when following a healthy diet. A common example of this is pernicious anemia, where the production of intrinsic factor is disrupted due to an autoimmune process.
2- Stomach acidity - Proper absorption of vitamin B12 from dietary proteins requires sufficient stomach acidity. If the acidity level is low, absorption of the vitamin from food becomes difficult.
3 - Long-term use of heartburn medications - Proton pump inhibitors and other medications that reduce stomach acid decrease the absorption of vitamin B12. This is not always a concern with short-term use, but the risk increases with long-term use.
4. Metformin – This medication is associated with a decrease in vitamin B12 levels. It does not directly destroy the vitamin, but it may inhibit its absorption in the intestines. Therefore, doctors usually advise people taking metformin for extended periods to monitor their vitamin B12 levels regularly.
5. Small bowel diseases: Vitamin B12 is primarily absorbed in the ileum. If this part of the intestine is inflamed, damaged, or dysfunctional, vitamin absorption becomes less efficient. This occurs in Crohn's disease and other conditions associated with malabsorption.
6 - Stomach and intestinal surgeries - Vitamin absorption may be affected after removal of the stomach or part of it or intestinal surgery.
7 - A strict vegan diet. The problem lies in its deficiency. Vitamin B12 is found in large quantities primarily in animal products. If a person completely excludes these products from their diet and does not consume fortified foods or supplements, the body will not have a source of it.
8 - Nitrous oxide - This is a less potent, but still important, agent. Nitrous oxide can affect the function of vitamin B12 in the body. Therefore, it is considered a cause of vitamin B12 deficiency or dysfunction, especially with repeated exposure.
Vitamin B12 levels are not affected by tea, coffee, or "unhealthy food combinations".
