Protein is a structural component of all body cells and aids proper nutrition. The average adult requires 0.8 g of protein per kilogram of body weight daily. Inadequate protein results in muscle breakdown and impairs cellular function. Protein is especially important for muscle growth and strength.
Protein provides amino acids used for muscle and cell repair in the body. Nine essential amino acids must be obtained from the diet while 11 nonessential amino acids are manufactured in the body. Essential amino acids include histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine. All essential and nonessential amino acids must be present for repair to occur and only some foods contain all essential amino acids. A varied diet tends to supply the best ratio of amino acids.
According to the book "Nutrition for Health, Fitness and Sport" by Melvin H. Williams, the quality of protein is based on its ability to provide amino acid requirements for growth, maintenance and repair. Animal sources such as eggs, poultry and beef are considered complete proteins because they supply all required amino acids. Eight ounces of 2 percent milk provides 138 calories and 10 g of protein while one large egg contains 102 calories and 7 g of protein. Low-fat varieties of animal protein provide benefits of amino acids with reduced caloric intake.
Plant sources such as beans, nuts and cereals are considered incomplete protein because they lack one or more essential amino acids. Plant sources must be combined to supply necessary amino acids for the body. One ounce of dry roasted almonds provides 167 calories and 6 g of protein while 1 cup of black beans contains 227 calories and 15 g of protein.
Protein content in grams is listed toward the bottom of all nutrition labels. Websites such as MyPyramid.gov and Nutritiondata.self.com allow you to look up nutrition data by food name and serving size. Web research allows you to find nutrition information for foods that may not have a label. Reading labels and researching protein content allows you to make healthful dietary choices to ensure proper nutrient intake.
Protein provides many health benefits for the body. Although various options exist for protein supplementation, it is best to obtain protein through the diet. Understanding protein values of food promotes adequate protein from dietary sources. Consult with a doctor before adding any supplement to your fitness routine.