Nutrients are substances -- such as carbohydrates, protein, fat, vitamins and minerals -- that nourish your body by aiding in growth and repair. Digestion begins in your mouth when you chew foods or swallow your dietary supplement pill. Each of these nutrients undergoes absorption, the final step of digestion, in a different way. Having any sort of digestive problem, such as irritable bowel syndrome, affects how well your body can digest and absorb nutrients. If you are currently taking a dietary supplement, including a multivitamin, let your doctor know.
Carbohydrates
Digestion and absorption of carbohydrates depend on the type of carb -- simple, complex or fiber. Except for fiber, carbohydrates absorb as glucose through walls in the small intestine. Glucose is the primary source of energy for all cells in your body. Simple carbs, such as sugars, are broken down into glucose in one step by an enzyme in the small intestine. Complex carbohydrates, like starch, require two steps in order to be absorbed as glucose. When you chew, saliva surrounds the complex carb, transforming it into a simpler form called maltose. The maltose then travels down to the small intestine where enzymatic juices further separate it into glucose. Fiber is different in that it is a type of carbohydrate not broken down into glucose; the body cannot break down or absorb fiber. Instead, fiber travels through the digestive tract, helping to excrete waste and allowing other nutrients to absorb.
Protein
Digestion of protein begins in the stomach and ends in the small intestine, producing amino acids, dipeptides and tripeptides. These are simple forms of the complex protein structure you ingest from the foods you eat that help build and repair muscle tissue and support brain function. Sodium carries amino acids through cell walls, allowing them to absorb, explains Jon Barron of The Baseline of Health Foundation. Hydrogen transports dipeptides and tripeptides in a similar way through cell walls, where they enter the bloodstream for absorption.
Fat
Bile acids from the liver break down large fat molecules during digestion in the small intestine. Digestion produces simpler molecules called fatty acids, monoglycerides or glycerols. These simplified lipids are absorbed in the small intestine by epithelial cells that cover the inside walls of the intestines. Epithelial cells are covered with tiny microvilli, which are finger-like structures that increase surface area so more absorption can occur.
Vitamins and Minerals
Vitamins are organic compounds made by humans and animals. Minerals are inorganic substances that come from soil and water and are absorbed by plants. You get minerals in your diet directly by eating plant foods, such as fruits and vegetables, or indirectly by consuming animal foods, since animals eat plants. Natural vitamins and minerals in the foods you eat are easier for your body to absorb, since they attach to small forms of lipids, sugars and amino acids. When your body absorbs these simple nutrients, the attached vitamins and minerals are also absorbed. Vitamins and minerals go into the bloodstream through intestinal walls. Getting supplements through injections, such as a B-12 shot, allows them to absorb directly into the bloodstream, bypassing the digestive tract.
Member Comments