Proteins are compounds in your body made up of amino acids, which contain carbon, oxygen, hydrogen and nitrogen. While protein can provide your body with energy because it has 4 calories per gram, this is not one of its primary functions. The proteins in your body, which come from the foods you eat, play six primary physiological roles.
Without proteins, you could not move, bend or even stand up straight. Proteins support your connective tissues, which are found in your tendons, ligaments and bones. These tissues connect your joints and allow movement. Other proteins, called actin and myosin, permit your muscles to contract. This allows you to run, sit and lie down.
Antibodies are substances that help fight off potential hazards to your body, like bacteria or viruses. When exposed to a pathogen, your body creates antibodies, which are made from protein, to keep you safe. Your immune system can produce up to 2,000 antibodies per second, according to “Nutrition and You” by Joan Salge Blake.
Some proteins in your body help transport various substances throughout your blood. A protein called hemoglobin, which is found in your red blood cells, brings oxygen to your tissues and carbon dioxide to your lungs. Other proteins bring vitamin A to your liver and eventually to your cells.
Other transport proteins are found in cell membranes. These proteins allow sodium and potassium to move in and out of your cells.
Proteins also serve as buffers, helping maintain the pH of a solution. When your blood becomes too acidic, protein side chains pick up excess hydrogen ions to increase the pH of your blood. If your blood becomes too basic, or alkaline, other protein side chains donate hydrogen ions to decrease the pH.
Your body contains approximately 60 percent water, making it the most abundant substance in your body. For you to stay healthy, this water must disperse properly throughout your body, and proteins help do this. Proteins attract water, so they can pull fluid into capillaries and prevent it from accumulating in your body tissues. Without proteins, your body tissues would become bloated, leading to generalized swelling called edema.
Enzymes are substances that speed up chemical reactions. Without enzymes, the chemical reactions in your body would occur so slowly, you would not be able to survive. Hormones are substances that direct a chemical reaction by turning enzymes on or off. Most enzymes and hormones in your body are proteins.
- "Nutrition and You"; Joan Salge Blake; 2008
- McKinley Health Center; Macronutrients: The Importance of Carbohydrate, Protein, and Fat; 2008