What is a known cause of B12 deficiency?

A known cause of vitamin B12 deficiency is the presence of antibodies to intrinsic factor. Intrinsic factor is a protein produced by the parietal cells of the stomach that is crucial for the absorption of vitamin B12 in the intestines. When the body produces antibodies against intrinsic factor, it can lead to pernicious anemia, a condition where the body cannot effectively absorb vitamin B12, regardless of the amount ingested from food sources. This can result in a deficiency of the vitamin, which is vital for red blood cell production, neurological function, and DNA synthesis.

Alcohol consumption may lead to certain nutritional deficiencies, including B12, but it is not a direct cause in the way that antibodies to intrinsic factor are. A lack of vitamin C does not directly cause B12 deficiency, as these vitamins play different roles in the body, and vitamin C does not affect the absorption of B12. Excess iron can lead to other health issues, but it does not typically contribute to B12 deficiency. Therefore, the presence of antibodies to intrinsic factor is the most direct and recognized cause of vitamin B12 deficiency.