User's Guide to Protein and Amino Acids: Learn How Protein Foods and Their Building Blocks Can Improve Your Mood and Health

INTRODUCTION

It seems hard to believe that protein—a nutrient absolutely essential for life—has become controversial. This User’s Guide demystifies protein and explains its many health benefits, as well as the importance of supplemental amino acids, which are the individual building blocks of protein.

Next to water, protein is the most abundant substance in the body. Approximately 20 percent of total body weight is made up of protein. Skin, hair, nails, muscles, eyes, and internal organs such as the heart and brain are largely made of protein.

Dietary protein is absolutely essential for growth and development of the human body. A diet absent in protein leads to malnutrition and ultimately death. As you can see, protein is an essential part of nutrition, as well as a primary component of the body’s composition.

Proteins play a critical role in virtually every physiological and biochemical process in the body. Proteins serve as cell communicators through the action of neurotransmitters. They are also essential for blood clotting, immune system development, and formation of milk during lactation.

A balanced diet should provide sufficient amounts of high-quality protein from a variety of sources. All proteins are not the same. For example, vegetable-based proteins provide different properties than animal-based proteins.

Between the pages of the User’s Guide to Protein and Amino Acids you will learn all about amino acids. You will discover how a particular sequence of amino acids strung together determines the unique qualities of a protein. Certain amino acids can be found in high amounts in some proteins, while they are absent in other proteins.

Any discussion of protein would not be complete without a discussion of the many diets being promoted today that are based on dietary protein intake. Fewer carbohydrates, more protein seems to be all we hear lately with regard to dieting. Is this the best advice?

The User’s Guide to Protein and Amino Acids explores different diets that are popular today. Fact is separated from fad regarding both high- and low-protein diets. You should walk away from this book with an understanding of how some diets are beneficial for short-term, rapid weight loss, while others are ideal for weight maintenance.

In the following chapters you will begin to understand the complex nature of proteins and the impact of protein intake on body weight and overall health. In addition, this User’s Guide will discuss the therapeutic benefits of different protein supplements, as well as individual amino acid supplements.

CHAPTER 1

WHAT IS A PROTEIN?

Protein was the first substance to be recognized as an essential part of health. The name protein was derived from the Greek word meaning of first importance.

Proteins, like carbohydrates and fats, are considered to be organic matter because they are made up of carbon, oxygen, and hydrogen molecules. These molecules, in combination, are responsible for the living tissues of plants and animals. Proteins are unique in that, unlike carbohydrates and fats, they are also made up of a nitrogen molecule.

Amino acid is the name given to the basic structural unit of proteins. Nitrogen molecules are combined with hydrogen molecules to make what is called an amino group (see Figure 1). Each amino acid also has a carboxyl group, which is made up of carbon, oxygen, and hydrogen. Amino acids have what is called an R group, which is a side group that distinguishes one amino acid from another.

Amino groups and carboxyl groups are not chemically reactive. Essentially, they are the stable part of an amino acid. The side group is what characterizes an amino acid and ultimately decides its fate. Amino acids can be charged or uncharged, acidic or basic.

To date, more than 300 amino acids have been described in nature. Of the 300, only 20 are commonly found in mammals.

Figure 1. Amino Group

WHERE DOES PROTEIN COME FROM?

Protein is one of three available energy sources found in food. Fats and carbohydrates also provide the body with energy from food. When food is ingested, the body is able to metabolically convert a usable form of energy called a calorie. Per gram of protein ingested, the body is able to manufacture 4.0 calories. For carbohydrates, 1 gram is also equivalent to 4.0 calories. One gram of fat, on the other hand, is equivalent to 9.0 calories.

Foods high in protein are complete proteins in that they have sufficient quantity and variation of all twenty amino acids. Examples of complete proteins are animal-based foods such as fish, poultry, beef, pork, and wild game. Eggs and dairy products also have sufficient amino acid composition and are considered complete.

NITROGEN: WHERE DOES IT COME FROM AND WHERE DOES IT GO?

Plants make protein from nitrogen that is obtained from ammonia and nitrates found in soil. Some plants, such as legumes, have the ability to extract nitrogen from bacteria in the atmosphere surrounding it. Animals obtain their nitrogen from eating plants and animals. When a plant or animal dies, the nitrogen in its fleshy tissue decomposes and nitrogen is returned to the soil.

THE QUALITY OF PROTEIN

Protein foods have been classified according to the body’s ability to digest and utilize them. The measurement of how efficiently our bodies utilize protein is called net protein utilization (NPU). This number is determined by the ratio of weight gained by a person on a particular protein to the weight that person gains on casein, a known high-quality protein derived from cow’s milk. This number is based upon the assumption that weight gain is proportional to the gain in body protein. This method determines whether or not a protein source has all twenty amino acids and in correct ratios.

NPU Net protein utilization; tells us how efficiently our bodies use a particular protein source.

Eggs from chicken are considered to have the highest NPU. After eggs, in descending order,