Proteins & Amino Acids

Proteins (polypeptides) are organic compounds composed of amino acids and are essential for all living organisms.  They participate in virtually every process within our cells, are vital to our metabolism, and have structural and mechanical functions that maintain cell shape, regulate cell signaling, support the immune response, and facilitate cell duplication.

Additionally, they perform biological functions, such as defense, protection, and transportation, within the body. The body requires 22 different amino acids to produce proteins, of which two are essential only for children. The body either produces these amino acids or must obtain them through diet.

Most microorganisms and plants can biosynthesize all 20 standard amino acids, while animals (including humans) must obtain some from their diet and digestive processes.

A complete protein contains 20 essential amino acids, and the nine essential amino acids are:

The Nine Amino Acids the body CANNOT make:

·  Histidine is essential in immune function, digestion, sleep, and sexual function.

·  Isoleucine helps produce hemoglobin, regulates metabolism, and supports muscles and immunity.

·  Leucine produces protein and growth hormones, repairs muscles, and helps regulate blood sugar.

·  Lysine produces hormones and calcium, and benefits immunity and energy.

·  Methionine absorbs zinc and selenium, is essential for growth, metabolism, and detoxification.

·  Phenylalanine produces your brain’s chemicals: dopamine, epinephrine, and norepinephrine.

·  Threonine produces collagen and elastin for the skin and maintains the structure of blood clots.

·  Tryptophan maintains nitrogen balance and produces serotonin, regulating mood and appetite.

·  Valine is responsible for muscle growth, tissue regeneration, and making energy.

The remaining amino acids are nonessential and include: alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine, and tyrosine.

Proteins are found in animal and plant products, but not all are equal.  Proteins containing the nine essential aminos acids are called “complete proteins,” while proteins containing fewer are  “incomplete.”

Complete Proteins:

Animal products: Fish, poultry, eggs, beef, pork, and dairy.

Vegetarian products: Soy, tofu, tempeh, quinoa, millet, chia, amaranth, and buckwheat.

Incomplete Proteins:

Legumes: Most beans

Grains: Whole “brown” grains have about 25% more protein than refined “white” ones.

Nuts and Seeds: Pumpkin seeds, almonds, and sunflower seeds.

Vegetables: Low in protein, with the highest percentages in spinach, broccoli, corn, and potatoes.

Many people worry that they won't get enough protein, especially if they avoid eating meat; however, combining different protein sources can help meet their daily requirements.

It is more challenging to obtain all the amino acids needed for complete proteins on a vegetarian or vegan diet. However, it can be achieved with the right food combinations. Most beans are low in methionine, while nuts and grains tend to be low in lysine; combining these foods can form a complete protein. An exception to this rule is quinoa and soy, both of which have complete amino acid profiles.

So, how much protein does the human body need? During World War II, the U.S. government commissioned a study that established the “Recommended Daily Allowances,” also known as RDAs. Then, in the early 1950s, the U.S. Food and Nutrition Board established a new set of guidelines, including the number of servings of each food group. These standards have been adopted in 40 countries worldwide, and the FDA and USDA have established that the recommended Dietary Allowance of protein for active adults is 3-5 ounces per day, which supports body structure and function.