Protein ensures functional body repair and growth, hormone and gene function and brain and immune health

• protein forms the structural tissues and compounds throughout your body which are continually being broken down and re-formed
• protein forms our genes, enzymes and critical messenger molecules in our bodies such as hormones and neurotransmitters
• protein is crucial for making white blood cells, antibodies and immune chemical messengers such as interferon (an antiviral substance produced by T lymphocytes and macrophages)

For absorption and use in your body, proteins are broken down into amino acids, from which proteins are formed. Amino acids are classed as being essential, non-essential or conditionally essential

Essential, non-essential and conditionally essential amino acids

Determining whether an amino acid is essential or non-essential is decided by whether your body can or cannot synthesise the amino acid within your body

• essential amino acids cannot be manufactured within your body are are thus necessary in dietary intake
• non-essential aminos can be manufactured within your body – however “non-essential” is determined by whether your body is given the right conditions to either manufacture or absorb amino acids (ie from food)
• conditional essentiality is determined by whether an amino acid is conditionally necessary to ensure normal body functionality – and is the most enlightened way of viewing amino acids

How a non-essential amino acid becomes “conditionally essential”

Conditional essentiality pays attention to what is happening both outside and within your body – these factors are critical in determining whether or not your body is either manufacturing or absorbing enough amino acids for the physiological activities they are needed for.

For example

• Arginine is used in wound healing, detoxification reactions, immune functions – thus use of Arginine by your body will increase during illness and healing, weight loss and detoxification as well as during growth phases, such as childhood and adolescence or muscular strength training
• Arginine is made within your body, however under these conditions where your body uses more than it can supply from normal sources, it becomes conditionally essential and needed in food intake

Protein quality and bioavailability

Protein quality is determined by the number of essential amino acids present in a food. All amino acids required for forming body proteins must be present and absorbed from food in the same meal. A complete protein source is a food that delivers the amino acids in the right qualities. Meat, fish, poultry and dairy foods are complete protein sources. Vegetable sources are often incomplete and foods must be combined (eg rice and beans) in order to become a complete protein source.

Bioavailability (or Biological Value: BV) refers to the ability of the body to absorb and make use of the protein and amino acids in a food source

• whey protein  and eggs have the highest BV
• milk, fish, beef and spirulina have an extremely high BV, making them the best food sources of protein

Adapted from:

Murray, M. (2005). Encyclopedia of Healing Food. New York, N.Y.: Atria Books

Haas, E. (2006). Staying Healthy with Nutrition. Berkeley, CA: Celestial Healing Arts.

Bland, J., Costarella, L., Levin, B., Liska, D., Lukaczer, D., Schlitz, B., Schmidt, M., Lerman, R., Quinn, S., Jones, D. (2004). Clinical Nutrition: A Functional Approach, Second Edition. Gig Harbor, WA: The Institute for Functional Medicine.