Amino acids are essential organic compounds with a primary function as building blocks for proteins. The body requires approx. 22 amino acids, in specific patterns, to assist with human protein. All but nine of these amino acids can be produced in the body.
The nine that cannot be produced are called essential amino acids because they must be supplemented into our diets. These are:
Methionine: Methionine is important in angiogenesis (the growth of new blood vessels). Supplementing with L-methionine has been shown to help heal wounds. The human body uses L-methionine to make creatine (another type of amino acid), plus L-methionine contains sulfur. This is used by the body for healthy growth and metabolism, and is responsible for a compound known as s-adenosylmethionine which supports the proper function of the immune system, neurotransmitters (like dopamine, serotonin and melatonin), and cell membranes. Foods that contain highest levels of methionine include chicken and fish, milk, red meat and eggs.  L-methionine can also be found in lower levels in fruits, nuts, veggies, grains and beans.
Threonine: Threonine is used in the biosynthesis of proteins. It helps maintain the proper protein balance in the body. It is found in high concentrations in the heart, skeletal muscle and central nervous system. It is important for the formation of tooth enamel, collagen, and elastin. It metabolises fat, prevents the build-up of fat in the liver, and is useful with intestinal disorders and indigestion. Foods that contain Threonine include beef, soy, pork, chicken, liver, cheese and shellfish. Lower levels are found in nuts, seeds, beans and lentils.
Tryptophan: tryptophan works on our serotonin levels – one of the key brain chemicals involved in regulating mood. It helps us achieve levels of calm, relaxation, and sleepiness. Without Tryptophan, serotonin would not be made. Foods that contain tryptophan include eggs, cheese, pineapples, tofu, salmon, turkey; and lower levels are found in nuts & seeds. All these will help boost your serotonin levels.
Leucine: Leucine is one of the branch chain amino acids (BCAA’s). It is important in stimulating muscular growth. It has the ability to modulate insulin sensitivity, has a catabolic effect on fat, and is one of the two amino acids which cannot be converted to sugar. Leucine has a key role in a variety of functions including hormone control, stabilising blood sugar levels, preventing muscle protein breakdown and facilitating muscle building or protein synthesis (the construction of new protein). Foods that contain leucine include: cheese, soybeans, beef, chicken, pork, fish, seafood. Lower levels are found in nuts, seeds and beans.
Isoleucine: Isoleucine is necessary for hemoglobin formation and in stabilising and regulating blood sugar and energy levels. It is one of the BCAA’s along with Leucine and Valine. Isoleucine is also important in stimulating muscle growth, it is stronger than valine, but much weaker than Leucine. Foods that contain Isoleucine are: milk & dairy, eggs, chicken, pork, beef, fish, salmon and sardines. Lower levels are found in nuts & seeds, soy, peas, beans, chickpeas, lentils and peanuts.
Valine: The last of the BCAA’s, it promotes normal growth, tissue repair, regulates blood sugar and provides the body with energy. Valine also helps stimulate the central nervous system and is needed for proper mental functioning. Valine also helps remove potentially toxic excess nitrogen from the liver, and is able to transport it to other tissues in the body as needed. Foods that contain Valine are: meat products, dairy products, and lower levels are found in mushrooms, peanuts and soy protein.
Lysine: many people use lysine to treat or prevent cold sores. Foods that contain Lysine are beans, cheese, yogurt, meat, milk, brewer’s yeast, wheatgerm, and other animal proteins.
Phenylalanine: is a building block of protein – the body uses it to make ‘chemical messengers’. Foods that contain phenylalanine are meat, cheese, eggs, milk, and fish.
Histidine: Histidine is used to develop and maintain healthy tissues in all parts of the body – particularly the myelin sheaths that coat nerve cells. It ensures transmission of messages from the brain to various parts of the body. Foods that contain histidine are meat & dairy products, and lower levels are found in grains such as rice, wheat and rye.
When a food contains all the essential amino acids, it is termed a ‘complete protein’. These are typically animal based proteins (meat, fish, eggs and dairy); but a few plant sources are also considered complete such as quinoa, buckwheat, hemp & chia seeds and spirulina.
For the body to properly synthesise protein, all the essential amino acids must be present at the same time and in the proper proportions, otherwise protein synthesis will fall to a very low level or stop altogether.
Most vegetables and fruit are what we call an ‘incomplete protein’ as they don’t contain all the 9 essential amino acids. These include nuts & seeds, legumes, grains and vegetables. Just because they are incomplete doesn’t make them inferior – they just need to be combined with other proteins to make a ‘complete protein’.
Proteins that in combination make a complete amino acid profile are know as complementary proteins. These include: rice & beans, spinach salad & almonds, hummus and whole grain pitas, wholegrain noodles & peanut sauce.
Essential amino acids may be taken in supplement form and should only be consumed with juice or other liquids (water).
Protein, no matter how good the quality, will not be used sufficiently and will not support growth, without the help of carbohydrates and fats to help prevent the body from using its protein for fuel.
In adults, a protein deficiency may result in lack of stamina, depression, weakness and poor resistance to infection and many other health problems.