Once Monosaccharides Are Absorbed, Where Do They Go?

As mentioned, monosaccharides (glucose, fructose, and galactose) are absorbed into the body by crossing the wall of the small intestine and entering circulation via a special blood vessel called the portal vein. As the portal vein carries blood from the digestive tract directly to the liver, the liver gets the first shot at the absorbed monosaccharides. The liver is able to pull most of the galactose and fructose from our blood as well as a respectable portion of the glucose (see Figure 4.2). However, much of the glucose continues past our liver and enters the general circulation where other tissue will have a shot at it. This increases the concentration of glucose in the blood from a normal or “fasting” level of 70 to 100 milligrams up to 140 milligrams of glucose per 100 milliliters of blood or higher.