Intrinsic factor is the most obscure — yet most important — glycoprotein in the human body. It has only one primary function that is essential for good health. Produced by the parietal cells of the stomach as well as the salivary glands, the intrinsic factor has a brief, but very important life. Intrinsic factor is key for supporting energy, metabolism, and mental health by working with one nutrient — vitamin B-12.
Why Is It Important?
To understand the importance of intrinsic factor, it’s necessary to understand the importance of B-12. Vitamin B-12 is involved in the metabolism of every cell in the human body. It plays a key role in DNA synthesis and formation, red blood cell creation, and brain function. The human body does not create vitamin B-12 on its own, so it must be consumed from the diet. The human digestive tract may have bacteria that produce B-12; however, dietary B-12 is the best way to ensure adequate nutrition.
Sources of B-12 include fish, shellfish, meat, liver, eggs, poultry, and dairy products. Batabata-cha, a Japanese fermented black tea, contains large amounts of B-12 which may be bioavailable to humans. This tea is considered to be a vegan source of vitamin B-12. Kombucha is also reported to contain varying amounts of B-12. Without this essential nutrient, neurologic problems result and, if left untreated, death follows. But B-12 has a problem — it cannot survive the trip through the stomach due to the stomach’s high acid content. Fortunately for us, that’s where intrinsic factor comes to save the day.
How Intrinsic Factor Works
Intrinsic factor binds to B-12 when it reaches the stomach following exposure to gastric juices. Bound with intrinsic factor, B-12 will survive the journey through the stomach and reach the small intestine. Once there, intrinsic factor dissolves, releasing B-12 to bind with another protein, transcobalamin II, for transit through the epithelial cells and into the bloodstream and on to the liver.
What Causes the Body to Stop Producing It?
Only the parietal cells of the stomach create enough intrinsic factor to supply the body with adequate B-12. When these cells are damaged, intrinsic factor is not produced, and B-12 goes unabsorbed. Alcoholism and ulcerative gastritis can cause parietal cell death, greatly increasing the chances of developing a B-12 deficiency. H. pylori infection, Zollinger-Ellison syndrome, and gastric bypass surgery also cause similar effects. Age may also play a role in intrinsic factor production.
The absence of intrinsic factor leads to a condition called pernicious anemia, or the inability to initiate intrinsic factor and B-12 absorption. In some cases, pernicious anemia can be passed down through families. This is most common in individuals of Scandinavian or Northern European descent. Certain diseases such as Grave’s disease, Addison disease, and type 1 diabetes may increase the risk of pernicious anemia. Individuals suffering from pernicious anemia may also be at an increased risk of gastric cancer.
What to Do in Its Absence
Anyone lacking intrinsic factor will need to supplement with B-12. However, since B-12 cannot be digested without intrinsic factor, it needs to be administered through regular injections. Although sublingual options exist, these may not provide adequate levels of B-12. Consult with your doctor to discuss the best options for you.
- Kittaka-Katsura H, et al. Characterization of corrinoid compounds from a Japanese black tea (Batabata-cha) fermented by bacteria. J Agric Food Chem. 2004 Feb 25;52(4):909-11.
- Annibale B, et al. Diagnosis and management of pernicious anemia. Curr Gastroenterol Rep. 2011 Dec;13(6):518-24. doi: 10.1007/s11894-011-0225-5.
†Results may vary. Information and statements made are for education purposes and are not intended to replace the advice of your doctor. If you have a severe medical condition or health concern, see your physician.