Protein And Amino Acids: Exploring the vital macronutrient

What is protein?

From a nutritional perspective, protein is one of the three macronutrients found in our diets. The other two macronutrients are fats and carbohydrates. 

Carbohydrates and proteins equate to four calories per gram, while fats are more than twice as energy dense with nine calories per gram.

Nutrition labels list protein amounts per serving, but this information is somewhat limited. A gram of protein from one type of food isn't the same as a gram of protein from a different type of food.

These subtle differences are due to the different component parts of proteins, called amino acids. The protein shown on a nutrition label doesn't indicate which protein parts make up the food in question.

What are the amino acids humans need?

Proteins are made up of different combinations of subcomponents called amino acids. Some amino acids can be created by our bodies while others must come from the foods we eat. 

Amino acids that we have to eat are called essential amino acids. Non-essential amino acids can be synthesized, or made, by our bodies.

A third type, semi-essential amino acids, are essential in certain circumstances while non-essential in others. For example, babies born prematurely have not developed the ability to produce enough non-essential amino acids. 

These non-essential amino acids, since they can't be produced in sufficient quantities by people in certain situations, are considered semi-essential amino acids.

What amino acids are found in the protein we eat?

There are 21 amino acids found in most biological life and humans need them all to survive. The nine essential amino acids are as follows: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.

The remaining 12 non-essential and semi-essential amino acids are the following (semi-essential amino acids are marked with an asterisk*): alanine, arginine*, asparagine, aspartic acid, cysteine*, glutamic acid, glutamine, glycine, proline, selenocysteine, serine, and tyrosine*.

Each of the 21 amino acids serves a special role in our biology and our diets need to contain them all. To help understand which foods contain all of the amino acids we need, food is sometimes referred to as a complete or incomplete source of protein.

What are complete and incomplete proteins?

Foods containing all of the amino acids, in sufficient quantities, are called complete proteins. In contrast, incomplete proteins are missing certain amino acids. 

You'll want to make sure you're getting all the amino acids from the foods you eat, though you don't need to get all of them from a single food.

How do I know if my diet contains complete or incomplete proteins?

One measure scientists use to determine the quality of protein in a food is called the Protein Digestibility Corrected Amino Acid Score (PDCAAS). The PDCAAS score calculates the value of a particular food based on the amount of each amino acid it contains. 

Scores range from zero to one. A food with a PDCAAS score of one, is considered to supply all the amino acids in sufficient quantities. Eggs and protein powders (e.g., soy, casein, and whey) are two types of foods that have a PDCAAS of one.

The PDCAAS has some qualities that make it an imperfect measure. One way the PDCAAS might be misleading is the fact that people usually eat meals with multiple foods that contain protein. 

So, a hypothetical food that contains large amounts of all but one amino acid would have a PDCAAS of zero. That food could still be considered an important part of a healthy diet, so PDCAAS won't always give you all the information you need to create a nutritional diet.

If you're consuming a balanced diet, then you're likely getting enough protein from the variety of foods you're eating. Unfortunately, it can be hard to know if you're eating a balanced, healthy diet.

Finding and Maintaining a Healthy Diet

Dr. Inman understands that figuring out and maintaining a healthy diet can be complicated. Your diet depends on a number of factors from how often you exercise to any conditions you're currently facing. If you have a nutrient deficiency, then you might need supplements to help you get back to typical levels.

With nutritional counseling, you'll get a thorough evaluation of your current nutritional habits. These habits have been built up over a long period of time, so Dr. Inman will help you understand which behavioral changes to make and which points to make steady progress toward your health goals.

Book a nutritional counseling appointment with Dr. Inman today and you'll be well on your way to holistic, full-body wellness.