Discussion of Macro-nutrients (Protein)

A macro-nutrient is a nutrient that is required in significant amounts in the diet. Three important classes of macro-nutrients are protein, carbohydrate, and fat.

Protein

Protein is the primary structural and functional component of every cell in the human body. Dietary proteins are used for growth and development and to build and repair cells; they also serve as enzymes, transport carriers, and hormones. Therefore dietary protein intake is essential for maintaining health, reproduction, and cellular structure

and function.

“Amino” means “nitrogen containing,”and amino acids are the molecules that, when joined in groups of a few dozen to hundreds, form the thousands of proteins occurring in nature. Proteins in the human body are composed of various combinations of the 20 individual amino acids. Four amino acids can be synthesized by the human body and are therefore considered“nonessential” because they do not need to be consumed in the diet. Nine amino acids are “essential” because the body cannot manufacture them—they must be obtained through the diet. And finally, eight amino acids are considered conditionally essential. These amino acids are typically not essential though they become essential,and therefore must be obtained through the diet, during times of illness and stress.

Animal-based proteins—including eggs, dairy foods, meat, fish, and poultry—contain all of the essential amino acids, while soy is the only plant-based protein that contains all eight essential amino acids. In general,plant proteins are less digestible than animal proteins.

Recommended daily protein intake for adults older than 19 years = 0.80 gram/kg body weight.

Athletes require more than the recommended daily allowance for protein to build and repair muscle. Depending on the sport and the training program, 1.0 to 1.7 g per kilogram body weight of protein is recommended.

Source: Essentials of strength training and conditioning: 4th edition.