Dissecting Amino Acids

Health Professional, Medical Reviewer

We've all heard that amino acids are important, but what are they, and why do they matter?   Here's a breakdown of amino acids and what they do for us.

What is an Amino Acid?

Amino acids are simple organic compounds that are the building blocks of proteins.     Hundreds of amino acids exist in nature, but only 20 of them are important for human nutrition. From these 20 amino acids, the body makes over 50,000 different types of proteins that play important roles in our bodies.

Why Are They Important?

Amino acids make up about 75% of our bodies.   They are essential to practically every bodily function, and each chemical reaction that takes place in the body depends on these amino acids and the proteins that they build. Amino acids are necessary to build the proteins that our body needs to grow, repair, and maintain body tissues.  This includes skin, hair, muscle, and organ tissue.

Essential vs. Nonessential: What's the Difference?

Essential amino acids are amino acids that can't be made by the body in adequate amounts, so they must be consumed from the foods that we eat. The essential amino acids include isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.

Nonessential amino acids can be made by the body if nitrogen and carbon are present. The nonessential amino acids are arginine, alanine, asparagine, aspartic acid, cysteine, glutamine, glutamic acid, glycine, proline, serine, and tyrosine.

Other Amino Acids

There are also semi-essential amino acids. They can sometimes be made by the body if conditions are perfect. Histidine is considered to be semi-essential because the body does not always need nutritional sources of it. Other amino acids, like carnitine, are used by the body in other ways (not for protein building) and are frequently used for therapeutic treatment, including conditions of the heart and blood vessels.

How Do I Get My Essential Amino Acids?

Essential amino acids must be eaten every day, since the body can't store them for later use (like it can for the fats and carbohydrates we eat). If you eat a variety of protein in your diet, you can get all of the essential amino acids that you need. Protein foods that contain all of the essential amino acids are called complete proteins.   All animal products contain complete proteins.   These include dairy products, meat, fish, poultry, and eggs.

What If I'm a Vegetarian or Vegan?

Vegetarians can get all of their essential amino acids from dairy products and eggs. Vegans can make complete proteins by combining certain foods to get all of their essential amino acids. Eating a variety of these foods will ensure that all essential amino acids are present to make complete proteins:

  • Soy (edamame and tempeh)
  • Nuts (peanuts, cashews, almonds, pecans, and Brazil nuts)
  • Whole grains (barley, rye, wheat, and rice)
  • Seeds (pumpkin, sunflower, and sesame)
  • Beans (lima, chickpeas, pinto, and navy)
  • Vegetables (corn, potatoes, onions, mushrooms, and broccoli)

You do not need to eat these foods at the same meal to make a complete protein. Vegans that consume a variety of these foods on a regular basis will ensure that their bodies are getting everything they need to make complete proteins.

How Do I Know If I'm Getting Enough of These Essential Amino Acids?

If you aren't eating animal products or a combination of the above incomplete protein sources, you may be at risk of essential amino acid deficiency. Low levels of these amino acids have been linked to symptoms such as irritability, poor concentration, fatigue, depression, and hormonal imbalances. Only a physician or dietitian can adequately assess your diet and health for a deficiency, so seek professional advice if you are experiencing any of these symptoms.