Are you wondering how vitamin B1 works in your body? Maybe you're taking some B complexes or just looking at your multivitamin and not sure how all these different vitamins work in our body and whether or not you need them. My name's Dr. Terranella, and in this video we're going to look at that specifically: how does vitamin B1 work in your body?

We'll look at what it does, what a deficiency might look like, what the RDA for vitamin B1 is, and how deficiency might present itself. So vitamin B1, also known as thiamine, is an essential water-soluble vitamin that plays important roles, mostly in metabolic processes in the body.
Its role in these metabolic processes is by serving as a coenzyme for specific enzymatic reactions.

A co-factor is basically a helper to an enzyme. Enzymes facilitate reactions. They take one substrate and turn it into a product, and in order for that to move forward smoothly, that enzyme needs a helper or a co-factor. And in this case, we're talking about thiamine or Vitamin B1 as that co-factor.The active form of thiamine or vitamin B1 is referred to as thiamine pyrophosphate, or TPP for short. This is the active form that's used for that coenzyme function.

The overall metabolic process that the thiamine or TPP is supporting as a co-factor is the decarboxylation of alpha keto acids. This is used again in metabolism and energy production for breaking down carbohydrates, fats, and proteins. So it's critical for things like glycolysis (breaking down glucose), the Krebs cycle and citric acid cycle, and the metabolism of branch chain amino acids and fatty acids.

There are specific enzymes that are being targeted in these specific areas of glycolysis, the Krebs cycle, fatty acid and amino acid breakdown. Let's look at those enzymes specifically, and then we'll go into more about how thiamine actually works in the body. The first enzyme, and I think this is probably the more critical one, or the one that most comes up clinically speaking, is the pyruvate dehydrogenase complex. Thiamine pyrophosphate or TPP is a co-factor for this enzyme complex, which catalyzes the conversion of pyruvate into acetyl-CoA.

When you don't have enough thiamine, less of the pyruvate dehydrogenase complex is formed, and so less of your carbohydrate metabolism is going to go into making energy. Instead, pyruvate can get shuttled across into lactate. Lactate can be helpful and has useful purposes in the body, but it doesn't yield nearly as much energy as pyruvate and the corresponding acetyl-CoA that comes from the pyruvate.

Alpha-ketoglutarate dehydrogenase is similar to pyruvate dehydrogenase in that it's working as a co-factor, turning alpha-ketoglutarate into succinyl-CoA. TPP is also used in a pathway known as the pentose phosphate shunt. This is one of the ways that the body can generate precursors to nucleic acids for DNA support. Finally, branch chain amino acids are broken down through the enzyme branch chain amino acid dehydrogenase. This is also a complex that thiamine serves as a cofactor for.

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