Most of the consumed riboflavin is released into its free form in the stomach.
Most of the consumed riboflavin is released into its free form in the stomach and is rapidly absorbed by the small intestine. In the intestinal mucosal cells (the inner lining of the bowel), it is converted to its active forms called flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN). From the small intestine, these forms get transported via the blood to various tissues of the body to perform their functions.
The major functions of riboflavin in the body include:
- Metabolism of nutrients: The active form acts as coenzymes for catalyzing (facilitating) the function of many flavoproteins, a group of mitochondrial enzymes involved in oxidation-reduction reactions for energy production. The enzymes are key factors in the body’s major metabolic process namely glycolysis, Krebs cycle, electron transport chain, and metabolizing carbohydrates, proteins, and fats. This process liberates energy in the form of ATP (Adenosine Triphosphate) required for cellular functions.
- Antioxidant and apoptosis: The flavoproteins play a pivotal role in protecting the cell membrane from the oxidative stress caused by free radicals. Glutathione reductase, a flavoenzyme, speeds up the reduction of glutathione disulfide to glutathione (the major antioxidant that quenches free radicals and makes them harmless). They are also involved in cellular apoptosis, which is programmed cell death. Apoptosis is required to get rid of unwanted cells in the body.
- Vitamin B3 (niacin) formation and homocysteine regulation: Riboflavin interrelates with other vitamins notably niacin, an essential nutrient mandatory to keep the skin, digestive, and nervous system healthy. Niacin requires FAD for its formation from the amino acid, tryptophan. It is also extremely important for the regulation of homocysteine (an amino acid derived from methionine) levels. High levels of homocysteine can increase the risk of strokes, heart attacks, or other heart diseases.