Continuing with ingested foods break down and use, the intestines are important in augmenting the absorption of certain critical substances to the body and to fuel it. Next the food enters the small intestine where sugars, fats and proteins are absorbed. Essentially the main building blocks and fuel for the body. Further digestion happens here as the contents of the gallbladder or if none from the liver and pancreas, which also entered to combine with the contents in the stomach and small intestine, assist digestion and absorption. Also continuing the selection of what organisms survive, again depending on vitamin D3 levels as to a degree the lower the weaker the immune system.

Another area that vitamin D3 has an effect is absorption of key nutrients in the small intestine. There in the last third of the small intestine, called the duodenum, where vitamin D3 and vitamin B12 are absorbed. There vitamin B12 absorption can be augmented by vitamin D3 through calcium which is needed for intrinsic factor to combine with vitamin B12. If no combination of intrinsic factor with vitamin B12 then it isn’t absorbed.

To complete the alimentary tract, as I have written before, the large intestine and essentially last main part of the alimentary tract, is like a huge fermenter. Think about making sauerkraut as a similar process but much more complex or it is like a huge chemical factory.  As trillions of organisms all potentially creating useful and/or harmful; substances. I should have done this sooner, but this gives a broad overview of what we currently know.

Ok back to the small intestine and vitamin B12.  I have written about calcium’s augmented absorption by vitamin D3, so I will now write about vitamin B12. As your probably already aware it is an important vitamin in numerous cellular pathways and the general understanding is it increases your energy level. As I wrote above it requires intrinsic factor in order to be absorbed from the gut. However, as we age its production decreases. First there are several forms of vitamin B12, which most people are unaware. 1

As they refer to these different forms of vitamin B12 as the “cobalamins”. Of these cobalamin’s methyl cobalamin and 5-deoxyadenosylcobalmin are the active forms that humans use. The injectable form as well as the oral form are both in the form of cyanocobalamin. Which once absorbed in the body are rapidly converted it to one of the 2 active forms listed above. There is no current evidence that absorption of any of the different forms of vitamin B12 is any better than another.

But how much we can absorb is determined by three things. One the availability of intrinsic factor. How much vitamin B12 is available in the food ingested. Finally, by how much gastric acid and gastric proteases there are to liberate vitamin B12 from the food that contains it.

“It is, for any consumed orally, upon ingestion in the stomach on ward to be separated from foods by hydrochloric acid and gastric proteases to create the free form or if in a supplemented it is already in the free form. In the stomach the parietal cells release intrinsic factor which combines with the free forms to allow its absorption in the distal ileum by receptor mediated endocytosis.” 2


1- Herbert V. (1998) “Vitamin B12”, In: E.E. Ziegler and L. J. Filer, Eds., Present Knowledge in Nutrition, 7th Edition, ILSI Press, Washington DC. P306-356.

2- Institute of Medicine. Food and Nutrition Board. (1998) Dietary Reference Intakes: Thiamine, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin and Choline. Washington, DC: national Academy Press.

*The information posted above is for educational purposes only. Always check with your doctor before initiating any changes in your medical treatment. If you do not, then The Two-Minute Health Fact, Dr. Judson Somerville, nor The Optimal Dose is responsible!


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