Protein, a nutrient found in animal products and some plant foods, has received a lot of press in recent years. Some experts say eat more protein to help you lose weight. Others say eat less to cut back on saturated fat. Who do you believe? The truth most likely lies somewhere in the middle.
Function
Proteins exist throughout out your entire body. From cells to tissues and organs, they are in a constant state of breakdown and renewal. They make up the basis of enzymes that drive chemical reactions. Over 10,000 different proteins form the basis of the human body and keep it function properly. Inadequate protein intake can have life threatening consequences: stunted growth, loss of muscle mass, decreased immunity and even heart and respiratory failure. Increasing protein intake, especially from plant sources, while cutting back on poor-quality carbohydrates may also decrease your risk of heart disease and help curb your appetite, suggests the Harvard School of Public Health website.
Sources
Animal and plant foods both contain protein. Animal sources include meat, poultry, eggs and fish. Dairy products like milk, cheese and yogurt also contain protein. Beans, lentil, chickpeas, nuts, seeds are protein-rich plant foods. Grains, vegetables and fruits, to a lesser extent, also provide small amounts of protein, says the Centers for Disease Control and Prevention or CDC. Once eaten, protein gets broken down into amino acids. These amino acids provide the building blocks to form new protein in the body. Your body does not store amino acids. Therefore, it needs a daily supply of amino acids to make new proteins.
Types
When it comes to eating protein, all foods are not equal. Twenty different amino acids provide the building blocks for protein in the body. More than half of them are made by the body, but you must get some through food. Scientist call these essential amino acids, and classifies foods according to the number they provide. A protein food that contains all the essential amino acids is called a complete protein. Animal products are complete proteins. When a food lacks one or more essential amino acid, it is an incomplete protein. Most vegetable sources of protein are incomplete, with foods like quinoa and soybeans being the exception. However, eating a varied daily diet should provide you with all the essential amino acids you need, unless you are a strict vegetarian. In this case, some extra planning is necessary.
Recommendations
The Institute of Medicine recommends that adults get a minimum of .8 g of protein for every kilogram of body weight per day to keep from breaking down your own tissue. For a 150 lb. woman, this equates to moderate intake of about 55 g of protein a day. The Harvard School of Public Health estimates that the typical adult American consumes approximately 15 percent of their calories from protein, slightly more than the IOM recommendations. If you are healthy, it advises aiming for 20 to 25 percent of your calories from lean protein foods to gain potential cardiovascular benefits. The USDA's Food Guide Pyramid provides useful information on specific types and quantities of protein foods.
Guidelines
The Harvard School of Public Health offers several guidelines for moderate protein intake. Eat a variety of plant and animal foods each day so that your body gets all the amino acids it needs. Beans, nuts and whole grains not only provide protein, but other beneficial nutrients like fiber, vitamins and minerals. When you eat animal products, make leaner choices such as skinless poultry and fish, lean cuts of red meat, and low-fat dairy products. Also eat less highly processed carbohydrates, such as cookies, chips and foods made with refined flour, and increase your intake of protein moderately. This may benefit your heart and your waistline.
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