Nutrition for Health and Performance – Part 2 – Macronutrients – Protein

Macronutrients are nutrients which are required in large concentrations in one’s diet, there are three macronutrients:

· Proteins

· Carbohydrates

· Lipids or Fats

This week we will cover protein.

When one thinks about protein, muscle is the first thing that springs to mind, that is because most of the protein in the human body is in fact in the form of skeletal muscle, bone tissue and organs, however these tissues are majority water with various portions of proteins.

Power and strength athletes are particularly interested in protein, its function and the role it has in the diet.

Proteins like Carbohydrates are made up of carbon, hydrogen and oxygen, however unlike carbohydrates and fats, protein contains nitrogen as well. The proteins within the body are made up 20 amino acids, majority of these amino acids can be synthesized by the body and are termed non-essential amino acids, and these do not need to be included in the diet.

There are however 9 amino acids which cannot be synthesized by the body , hence being referred to as essential amino acids which need to be supplied via ones diet.

The amino acid content within the proteins affects its ability to promote both growth and tissue repair, thus protein quality is highly important.

The high quality proteins include red meat, fish, eggs and poultry, low quality proteins are those which lack in one or more essential amino acid such as grains, beans and vegetables. This is where vegans experience complications, as plant proteins are referred to as low quality proteins, therefore to obtain the required daily protein wide variety of plant foods must be consumed to ensure that all the necessary amino acids are taken in.

In athletes the protein requirement is elevated, both endurance and resistance training athletes, in the endurance athletes, the increased requirement is due to tissue repair requirement and in the resistance athletes also require more protein to fuel tissue repair as well as to ensure a positive nitrogen balance to maximize hypertrophy.

Athlete Requirements:

Research has shown that the daily protein requirements for aerobic athletes is 0.8g/kg of Body weight and can reach up to 1.4g/kg of body weight , activity dependant.

Strength and resistance athletes have a requirement of 1.7 g/kg of body weight.

However because most individuals do not fall into one of these training groups , a general requirement for a broad spectrum of athletes has been developed , 1.50 – 2.0g/kg body weight, will supply the body with adequate amounts, assuming that at least 65% of the protein is of a high biological value, therefore vegans may require in excess of 2.0g/kg body weight.

There have been some concern for negative effect of an intake of protein in excess of 0.8g/kg body weight, but these are unsubstantiated, specifically in the healthy individual as the excess protein is broken down and the nitrogen is expelled as urea in ones urine and the ketoacids are used in one of two paths, as a direct energy source or converted in carbohydrates via glucogenisis.

Reference : Essentials of Strength Training and Conditioning, 3rd Edition. T.R. Beachle & R.W. Earle (2008)

Wade Botha

Bachelor of Sport Science

HONS Exercise Science 2010 UKZN