Protein is essential for growth and development. It provides the body with energy and is required by the immune system for hormone production, growth and maintenance of tissues and is a component of blood. Protein takes up approximately 20% of body weight and is also a component in muscles, hair, nails, skin, eyes and internal organs. The amount considered necessary for the body varies, depending on growth, illness and other factors such as stress and physical activity.
What you need to know:
- Proteins are part of the living tissue of all plants and animals.
- Proteins are molecules made up of 22 amino acids.
- Amino Acids are the building blocks of human cells and tissues.
- Nine of these amino acids are considered essential.
- Essential amino acids must be included in the diet as the body cannot make them on its own.
- These nine essential amino acids are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine.
- Cysteine and tyrosine can be manufactured by the body from methionine and phenylalanine and are considered to be semi- essential.
- Adults require 15 percent of their total protein intake to be in the form of essential amino acids. Protein is critical to the following vital bodily functions:
- Cell growth
- Energy production
- Enzyme, hormone, neurotransmitter and immunoprotein production
- Maintenance of normal pH balance in the body. The body uses all 22 amino acids and a small amount is stored in the liver and cells of the body. Any excess protein in the form of amino acids is converted into energy or stored as body fat. Protein is contained in vegetable and animal sources. Complete protein is most abundant in animal foods such as beef, pork, lamb, fish, poultry, eggs and dairy products.
Vegetables and fruits contain adequate levels of some essential amino acids but may be low in others. Soybean products such as tofu and soymilk are complete proteins. Grains, legumes (beans, peas, and lentils), nuts and seeds need to be combined with other foods to form a complete protein.
Combining to form a complete protein:
Grains + Legumes = complete protein. Grains + Nuts = complete protein. Legumes + Nuts = complete protein.
• Grains include wheat, rye, barley, oats, rice, corn, flour and bread.
• Legumes include beans, peas, lentils, tofu, tempeh and peanuts.
• Nuts include sunflower seeds, pumpkin seeds, sesame seeds, walnuts, almonds and cashews.
Protein deficiency is uncommon in Western diets. People who may be at risk of protein deficiency are those on calorie restricting diets. A diet that is not balanced and is low in energy (calorie) intake can cause the body to convert existing protein stores into energy. This means that there is less protein available for other vital bodily functions. A deficiency in protein can adversely affect the immune system and increase the risk of infections.
Protein deficiency may lead to:
- Abnormal growth.
- Lack of vigour and stamina.
- Mental depression.
- Slow healing of wounds.
- Slow recovery from disease and low resistance to infections.