Mutual Supplementation: How to Use Dietary Proteins

Proteins function in structural capacities and as enzymes, hormones, transporters, and immunological protectors.

Introduction

The body uses dietary proteins that have been broken down into amino acids. The quality of protein depends on its indispensable amino acid composition, and digestibility. Foods containing protein are categorized as complete proteins or incomplete proteins. Complete proteins contain amino acids as required by humans. Cheese, eggs, fish, poultry, milk, meat, and yogurt are sources of complete proteins. Incomplete proteins are low-quality proteins. Cereals, grains, legumes, and vegetables are sources of incomplete proteins. A diet with only low-quality proteins is unable to supply amino acids and inhibits the ability to synthesize proteins. It is important to ensure that the all indispensable amino acids are received by the body. This is achieved by mutual supplementation. Digestibility is a measure of amino acid absorption. Plant proteins are 70-90 percent digestible, whereas animal proteins are 90-99 percent digestible. 

Use of Dietary Proteins

Amino acid pools contain dietary protein and proteins from breakdown of body tissue. Amino acids are used for synthesis of new proteins – growth and/or replacement of new proteins; production of non protein molecules; oxidation – as sources of energy; and for the synthesis of glucose, ketones, or fatty acids. Amino acid metabolism occurs primarily in the liver.

The size of the body, age, physiological state and the level of energy intake are factors that influence protein requirements. Generally, adults require 0.66 g protein per kg weight per day, and the recommended dietary allowance (RDA) is 0.8 g protein per kg body weight per day. Inadequate protein or energy can cause protein deficiency. Kwashiorkor is a form of protein malnutrition characterized by enough energy but inadequate protein. Marasmus is another form of protein malnutrition characterized by prolonged energy insufficiency and protein intake.

Conclusion                                                        

Nine amino acids are essential components of dietary proteins. Diets must be developed based on mutual supplementation to ensure indispensable amino acid availability, and digestibility.

References

Gropper, S., Smith, J. & Groff, J. (2008). Advanced Nutrition and Human Metabolism. Cengage Learning. Belmont, CA. 1-600.