Proteins are part of every cell, tissue, and organ in our bodies; and are constantly being broken down and replaced. Protein accounts for 20 percent of our body weight, performing a wide variety of functions throughout the body as vital components of body tissues, enzymes, and immune cells. Protein is made up of amino acids that are later used for tissue repair and maintenance in the body. There are 20 different amino acids that join together to make the different proteins; some are made in the body, others are not. The amino acids that cannot be made by the body are called essential amino acids; it is essential that our diet provide these.
Dietary protein sources are evaluated according to how many essential amino acids they provide. Complete proteins are those that provide all of the essential amino acids. Animal-based foods, for example, meat, poultry, fish, milk, eggs, and cheese, are considered complete protein sources. Incomplete proteins on the other hand, are those that are low in one or more of the essential amino acids, i.e rice, beans, legumes, etc. Complementary proteins are two or more incomplete protein sources that together provide adequate amounts of all the essential amino acids; an example includes tofu and brown rice or rice and beans.
Although some protein is needed for muscle growth, most people overemphasize protein needs and forget about vegetables! The average American eats about three times the amount of protein he or she actually needs. Think about the size of your palm or a deck of cards as a general rule for animal protein serving sizes, and a bit more for plant protein. Your plate should be balanced with three times as many vegetables to protein, to deliver adequate vitamins, minerals, and other plant nutrients.
Next time you are at the grocery store start by noting the variety of foods, or lack thereof, in your cart. Eating a variety of foods provides a greater opportunity to take in nutrients, such as protein, carbohydrates, fat, vitamins, and minerals which your body needs to stay healthy.
How much do you need? In general, it's recommended that 10 to 35 percent of your daily calories come from protein. The Recommended Dietary Allowances (RDA) vary by different age groups. Generally women aged 14 and over require at least 46 grams and men 14 and over require at least 52 grams a day. A great rule of thumb to follow is to aim for 20 grams of protein per meal.
Shop Carefully: Look for protein-rich lean meats, poultry, and fish, as well as dairy products (cottage cheese is an excellent source of protein), legumes, tofu, nuts, and nut-butter. Beans and vegetables are also good sources of protein.
• A 3-ounce piece of meat has about 21 grams of protein
• 1 cup of dry beans has about 16 grams of protein (but needs to be paired with rice, nuts, etc. to be considered "complete")
• An 8-ounce container of yogurt has about 11 grams of protein
Focus on variety and your protein needs will surely be satisfied.
— Phil Lempert, Supermarket Guru