A vegetarian diet is devoid of most, if not all, animal products. There is a wide variety of eating habits among vegetarians, however. The lacto-ovo vegetarian diet includes milk (lacto) and eggs (ovo), whereas the lacto-vegetarian diet excludes eggs. Animal products have more protein than most plant products, yet it is easy to meet your protein requirements on a vegetarian diet with a little planning. The American Dietetic Association states that an appropriately planned vegetarian diet can be nutritionally adequate at any stage of life.
What Are Amino Acids?
Of more than 300 amino acids in nature, 22 are important for human metabolism. Amino acids have many uses throughout the body, as in building muscle, transmitting brain signals and transporting oxygen in red blood cells, to name a few. Amino acids are called the "building blocks" of protein. The amino acids link together, like strings of beads, to form different types of proteins. With so many varieties of amino acid "beads," and varying string lengths, there are endless combinations of possible protein "necklaces." Proteins can be taken apart, and the available amino acids can be "restrung" in a different combination to make new proteins or used for non-protein purposes.
What Are Essential Amino Acids?
Amino acids are supplied from protein sources, externally from the diet or internally from the breakdown of proteins. All amino acids are crucial for sustaining life, but a distinction is made between amino acids the body can make and those it cannot. Those that cannot be made in the body -- phenylalanine, valine, threonine, tryptophan, isoleucine, methionine, leucine and lysine -- are considered "essential" because they must be obtained from the diet.
Complete Proteins
All proteins supply amino acids, but not all essential amino acids are in every type of protein. The number and variety of amino acids that comprise a protein determine whether it is "complete." Animal proteins, like meat, eggs, and milk, are considered complete proteins because they have all eight essential amino acids in the proper proportions. With the exception of spirulina, quinoa and soybeans, there are no plant sources of complete proteins.
Complemetary Proteins Help Vegetarians Meet Their Essential Amino Acid Needs
Most plant proteins are incomplete, as they lack one or more essential amino acids. This means, for vegetarians especially, it is important to get protein from a variety of sources so all essential amino acids are available in the diet. For example, cereal grains are low in lysine, so a vegetarian whose protein source is mostly grains may not get enough lysine. To ensure an adequate intake of lysine, simply add a high-lysine protein source like legumes or soybeans. Grains and legumes (rice and beans) are complementary proteins because when eaten together they supply the essential amino acids in the proper proportions.
Member Comments