Protein is an essential part of the diet because proteins are broken down into amino acids, which are necessary for a variety of bodily functions, including hormone production and muscle growth. There are 20 different amino acids, and your body can only manufacture 11 of these. The other nine amino acids, called essential amino acids, cannot be made by your body and therefore must come from your diet. Foods that provide all nine of these amino acids are called complete proteins. Animal products provide complete proteins, while most plant products are incomplete proteins.
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Meat and Fish
Meats are quality sources of protein because they provide all nine essential amino acids. However, meats can be high in fat, saturated fat and cholesterol so it is important to choose meat proteins wisely. For example, a 3 oz. hamburger made with 85 percent lean beef contains 21 g of protein, but also contains 12 g of fat, 4.5 g of saturated fat and 73 mg of cholesterol. A 3 oz. top sirloin steak contains even more protein, with 26 g, but only 6 g of fat, 2.1 g of saturated fat and 71 mg of cholesterol. When choosing meats, look for lean cuts of beef such as loin or round, choose white meat poultry over dark meat and choose low-fat cooking methods, such as grilling and broiling. Most fish is high in protein and low in fat, but some seafood, such as shrimp, is high in cholesterol.
Eggs and Dairy Products
Like meats, dairy and eggs provide complete proteins, but you should stick to low-fat and low-cholesterol choices. Eggs are especially high in cholesterol, with one egg supplying 186 mg, which is more than half the maximum amount recommended per day. However, all of the cholesterol in eggs is contained in the yolk, which makes egg whites an excellent low-cholesterol protein source. One egg white contains 3.6 g of protein, with only 17 calories, less than 0.1 g of fat and no saturated fat or cholesterol. Low-fat Greek yogurt is also an excellent source of dairy protein, with some brands containing more than 20 g of protein in 1 cup.
With the exception of soybeans, plant products do no provide complete proteins, as they are missing one or more of the essential amino acids. However, many plants products, such as pinto beans, which contain 15 g protein per cup, are still excellent sources of protein and can be combined with other plant proteins to make complete proteins. For example, beans can be combined with rice, corn, nuts, seeds or wheat to provide all nine essential amino acids. Most beans and some nuts contain a significant amount of protein.
Daily Protein Recommendations
Adult men need 56 g of protein per day and adult women need 46 g. When choosing protein sources, keep in mind that if you follow a 2,000-calories diet, you should also keep your fat intake below 75 g per day, your saturated fat intake below 20 g and your cholesterol intake below 300 mg.