Which of the following may be a consequence of reduced gastric intrinsic factor?

Reduced gastric intrinsic factor can lead to vitamin B12 deficiency because intrinsic factor is a protein secreted by the stomach that is crucial for the absorption of vitamin B12 in the intestines. Without adequate amounts of intrinsic factor, the body is unable to effectively absorb vitamin B12, which can result in various health issues, including megaloblastic anemia and neurological problems. The importance of intrinsic factor highlights its role in ensuring that vitamin B12, which is vital for DNA synthesis and red blood cell production, can be adequately utilized by the body.

In contrast, options involving vitamin D absorption, iron metabolism, and protein digestion do not directly connect to the function of intrinsic factor. Vitamin D absorption mainly occurs in the small intestine and is not dependent on intrinsic factor, while iron metabolism is influenced by various other factors, including dietary intake and overall gut health. Protein digestion primarily relies on enzymes secreted by the stomach and pancreas rather than intrinsic factor. Therefore, understanding the specific role of intrinsic factor clarifies why a decrease in it directly impacts vitamin B12 absorption.