Our bodies need proteins. Like carbohydrates and fats, proteins are an important building block material for our bodies. Proteins are important for organ function and also provide energy. Examples of proteins include enzymes and many hormones important for digestive, muscle, kidney, heart and brain function. Proteins are constructed using twenty types of amino acids. Our cells need all twenty amino acids for proper function. However, our cells cannot manufacture all twenty amino acids, instead making only about twelve. This means that we must get the rest from our diets. The eight amino acids that must be obtained from our diets are known as essential amino acids. If we have less than twenty amino acids, we end up impairing the functions of other molecules dependent on specific proteins for their functions.
Most people get the recommended daily supply of protein and sometimes more than what is needed daily by the body. There are different types of proteins, from different sources; animal and plant sources. Common animal sources of protein include meats, poultry, eggs, fish, other seafood and dairy products. Vegetable sources include leafy greens, legumes, peas, nuts, seeds and soy products. Protein rich foods may contain saturated fats, cholesterol, high sodium and fiber in addition to minerals, vitamins and phytonutrients. Eating a variety of protein rich foods is important, not only to balance meals and obtain the complete amino acids but also to obtain the other beneficial nutrients found in protein rich foods. How much protein is needed a day? The recommendation is to eat no more than 46 grams (for women and teenage girls) or 56 grams for men and 52 grams for teenage boys. Pregnant and nursing moms need up to 71 grams/ day and babies need about 10 grams /day. The total calorie intake from proteins should be at least 10 % but not more than 35%.
According to the Dietary Guidelines for Americans 2015-2020, most people get their protein from beef (ground beef), chicken, processed meats and eggs. Additional protein is obtained from seafood such as shrimp, tuna or salmon but the daily protein intake from seafood is below the daily recommendations. Protein is also obtained from peanuts, peanut butter, almonds and mixed nuts. About 49% of protein foods are eaten separately and about 45% are eaten as mixed foods in sandwiches, burgers and tacos. What the guidelines also show is that we need to develop three things that will help us stay healthier longer: developing a healthy eating pattern, eating a variety of nutrient dense foods and practicing portion control and limiting calorie intake from added sugars, saturated fats and reducing sodium intake (Dietary Guidelines for Americans 2015-2020). An important point from the recommendations is the need to decrease the amount of protein consumed by men and boys. Increasing fruits and vegetables and reducing saturated fats and cholesterol is seen as a way to reduce the risk of many chronic diseases such as heart disease, type II diabetes and some cancers. Eating variety also means that meats (beef, poultry) should be lean. A serving of meat is about 3-4 ounces and this provides enough protein. As with carbohydrates and fats, moderate consumption of proteins is important.
Excess protein can be harmful. The liver processes break down products released from proteins during digestion. The products are converted into urea which reduces the toxic effects of these products. The kidneys remove the urea with the help of water. We need to drink adequate amounts of water to help the kidneys function well. Consuming large amounts of proteins, with insufficient amounts of water can lead to dehydration and the formation of kidney stones.
U.S. Department of Health and Human Services and U.S. Department of Agriculture. 2015 – 2020 Dietary Guidelines for Americans. 8th Edition. December 2015.