Introduction
Amino acids act as miniature chemical building blocks for proteins in the body and are essential to life. There are approximately twenty-eight commonly known amino acids and, through the creation of proteins, help provide the structure for all living creatures. Amino acids are found in all food sources that contain protein. The various proteins that make up the human body do not come directly from the diet. Dietary protein is broken down into amino acids that are then used to build necessary proteins.
As with water, proteins are an essential component of every cell in the body. Indeed, protein is second only to water in comprising the greatest portion of body weight. Proteins play a role in bone, muscle, organ, and gland structure and function. All hormones and enzymes that regulate and promote various body functions are proteins. Proteins also aid in regulating water balance which helps maintain proper pH levels in the body.
Some amino acids function as neurotransmitters, carrying information from one nerve cell to another, while others act as precursors to neurotransmitters. Other amino acids, such as L-glutamine and L-tryptophan, are needed for your brain to properly receive messages. These neurotransmitters are able to pass the blood-brain barrier, which helps defend and protect against foreign invaders and toxins that may be circulating in the blood stream. Those amino acids that clear this barrier are used by the brain to communicate with nerve cells elsewhere in the body.
Essential vs. Non
Proteins are synthesized from twenty different amino acids. The liver produces eleven "non-essential" amino acids while the remaining nine "essential" amino acids must be obtained from the diet.
A deficiency of even one essential amino acids can result in severe physiological problems. It is important to obtain all essential amino acids from a variety of dietary sources (see Sources and Combinations, below). The essential amino acids are: L-histidine, L-isoleucine, L-leucine, L-lysine, L-methionine, L-phenylalanine, L-threonine, tryptophan, and L-valine.
Non-essential amino acids are manufactured by the body as needed. They are required for proper health and growth, but it is not necessary to obtain them through the diet as with the essential amino acids. The non-essential amino acids are: L-alanine, L-arginine, asparagine, aspartic acid, citrulline, L-cysteine and cystine, gamma-aminobutyric acid, glutamic acid, L-glutamine, glycine, ornithine, L-proline, L-serine, L-taurine, and L-tyrosine.
L vs. D
When reading amino acid listings off multi-amino acid complexes or protein powders, you will almost always see each acid preceded by an "L" or "D". These letters refer to the orientation of the amino acid molecule.
"D" stands for "Dextro" and is Latin for "right". L stands for "Levi" and is Latin for "left". D and L aminos are mirror images of each other. The two terms indicate the direction of the rotation of the spiral that is the chemical structure of the molecule.
Proteins in animal and plant tissue are made from L- forms of amino acids. This excludes the amino acid L-Phenylalanine, which is prepared in the form DL-Phenylalanine (a mix of both D and L forms). Typically, DL-Phenylalanine is used as a painkiller I supplementation.
"D" is often a synthetic form of an amino acid while L is the more natural form. L- amino acids are also most compatible with human biochemistry.
The Building Blocks
There is a continuous process of assembling amino acids to build proteins and of breaking down protein, for use in the body. The body will produce different types of proteins, such as those for cells and enzymes, as required. If the body becomes depleted of any essential amino acids, corresponding proteins will not be produced.
When only one amino acid is missing, proper protein synthesis will not continue. This situation can lead to amino acid deficiencies, regardless of a well balanced diet. Stress, drug use, age, nutrient imbalances, trauma, infections, and impaired absorption all affect essential amino acid absorption in the body.
If your diet is lacking in adequate amounts of essential amino acids, a number of physical disorder will become apparent. In addition, protein deficiencies usually manifest as intense sugar cravings. Instead of reaching for candy or baked goods, however, read the following section on protein sources and combinations.
Sources and Combinations
Protein quality is as important as quantity when considering dietary intake. Milk and eggs provide the best assortment of essential amino acids. However, those with a lactose deficiency or high cholesterol, vegetarians, or vegans, may find these amino acid sources inappropriate. Other preferred sources of protein include organic non-GMO soybeans, organic cheeses, non-farmed fish, or organic poultry and beef. Each contains low levels of several essential amino acids and must be combined with other sources to ensure complete essential amino acid intake.
Legumes, nuts, seeds, grains, and vegetables are considered poor sources of protein on their own. However, these foods can be strategically combined to complete your amino acid intake. Legumes should be combined with foods made from grains or nuts and seeds to provide an optimal, complete intake. Vegetarians should (and do) employ this practice to ensure dietary health. Specific combinations follow:
| Legumes & Grains Combinations Baked beans and wheat bread Bean burrito in corn tortilla Bean soup with wheat and barley Tofu dishes with rice | Legumes, Nuts & Seeds Combinations Lentil curry and cashews Tofu/vegetable stir-fry with sesame seeds Ground chickpeas (hummus) and sesame seeds Roast soybeans and nuts and seeds |
Protein supplements are often available in powdered form and can be prepared with organic milk, organic non-GMO soymilk, pure juice, or filtered water. If supplementing, choose "complex amino acids" protein preparations that contain both essential and non-essential amino acids.
Whey, a protein powder, is a by-product of milk and also offers a "complete" amino acid payload. Its protein content has the best absorption in the body, and it is low in fat, carbohydrates, and sugar. Studies show that whey can increase the amino acid-type substance glutathione, which boosts the immune system. Whey stabilizes blood sugar and prevents degenerative diseases. Note that whey supplementation may be inappropriate for vegetarians/vegans. A number of soy-based alternatives are readily available. Consult your nutritionist, personal trainer, naturopath, other health practitioner, or the nutritional/supplement staff of your local health food store.
Maintaining A Balance
Consuming large amounts of protein is not recommended. High levels of protein intake put excess demand on the liver and kidneys. Fifty percent of ingested amino acids are converted to glucose by the liver and used to provide cellular energy. This natural process produces ammonia -- a waste product that is toxic in the body. The liver converts ammonia to urea, a less toxic compound, urea, which travels through the bloodstream, is filtered out by the kidneys, and is excreted.
As long as the liver is functioning properly, ammonia is neutralized when it is produced and becomes harmless. High levels of protein intake, poor digestion, strenuous exercise, an acidic diet, serious illness, and liver defects can result in too much ammonia for the liver to process. As a result, toxic levels can accumulate in the body.
Balance is important when it comes to amino acids and protein in the body. Maintaining healthy amino acid and protein levels also ensures optimal absorption and use of vitamins and minerals. Many amino acids enable vitamins and minerals to perform their functions properly.
For More Information
For more information on specific amino acids, browse the listings in this section!
