Which of the following statements is TRUE regarding intrinsic factor?

Intrinsic factor is a glycoprotein that plays a crucial role in the absorption of vitamin B12 in the intestines. It is secreted by parietal cells, which are located in the lining of the stomach. This secretion is essential for the formation of a complex with vitamin B12, enabling its absorption in the distal ileum of the small intestine.

The presence of intrinsic factor is necessary because, without it, vitamin B12 cannot be efficiently absorbed, leading to potential deficiencies that can result in serious health issues, such as pernicious anemia. This mechanism highlights the importance of intrinsic factor in gastrointestinal physiology and nutrient absorption.

The other statements do not accurately describe intrinsic factor. For instance, it is not secreted by liver cells, nor is it directly involved in the absorption of iron. Additionally, while it is important for the absorption of vitamin B12, it does not significantly influence the absorption of folate. Thus, the statement about intrinsic factor being secreted by parietal cells is the one that correctly identifies its role and source within the body.