Amino acids are the building blocks of protein, both in the foods you eat and in the body you inhabit. Protein exists in every cell in your body, but the biological reactions necessary to support life involve the constant breakdown and replacement of cell proteins. This is why it is necessary to continue consuming protein and the amino acids that form it.
Essential and Nonessential Amino Acids
Proteins are made up of 20 different types of amino acid. Your body can synthesize some of these amino acids, but others, called the essential amino acids, must be obtained in your diet. There are 10 essential amino acids your diet must provide, and 10 nonessential amino acids your body produces on its own. The 10 nonessential amino acids are alanine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine and tyrosine. The 10 essential amino acids are arginine, which is required only in those who haven't yet reached adulthood, histadine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine.
Complete Protein in Foods
Some foods contain all 10 essential amino acids, and a food in this category is referred to as a source of complete protein. Foods from animal sources, such as meat, fish, poultry, eggs and dairy products, contain complete protein. Foods that contain some but not all of the essential amino acids are referred to as incomplete proteins. These include rice, beans, nuts and seeds.
Food Combining
It was once believed that in order for vegans -- vegetarians who consume no animal-based food sources -- to obtain adequate dietary protein, they needed to abide by a complex system of food combining, consuming various incomplete protein foods together to obtain fulfill their protein requirement. This is now known not to be the case. As long as vegans maintain a varied diet rich in incomplete protein sources, they do not have to combine these foods in any particular way.
Protein Requirements
The Centers for Disease Control and Prevention says most males over the age of 19 require 56 g of protein daily. Women over the age of 19 are advised to consume 46 g or protein daily. To gauge how much protein a particular food contains, read the nutritional label. The USDA National Nutrient Database is a great searchable online source for researching the amino acid content of specific foods.
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