Nutrient - Amino Acids
Amino acids are known as the ‘building blocks of protein’. Protein is essential for life. It is made from carbon, hydrogen, oxygen and nitrogen and, sometimes, sulphur. Protein is found in all our body’s cells and is needed to make up the structure and function of these cells. Skin, hair, nails, muscles, hormones, organs, antibodies, blood cells, bones and enzymes are all made of protein.
Most amino acids are made in the body from other amino acids – these are called ‘non-essential’ amino acids. Some amino acids cannot be made in the body, so must be present in food – these are called ‘essential’ amino acids and include isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine. Histidine and arginine are also essential amino acids but are needed only by children during growth. Meat, fish, eggs, poultry, dairy products and soya foods provide all essential amino acids. Plant foods are usually either very low or completely devoid of one or more of these nutrients, so it is important that plant foods are eaten together to make up the ‘complete protein’. For example, eating rice with beans, or bread with peanut butter.
Amino acids are sorted into groups, which work together:
Sulphur amino acids: cysteine, glutathione, methionine, taurine. So called because they contain sulphur in their structure. These help liver detoxification.
Branched chain amino acids: isoleucine, leucine, valine. So called because they contain a "branched methyl group" on the end of their structure. They form major parts of muscle protein.
Urea cycle amino acids: arginine, citrulline, ornithine. Help remove ammonia from the body.
Glucogenic amino acids: alanine, cysteine, glycine, serine, threonine. Can be used to make glucose for energy if needed.
Amino acids are usually given the letter ‘L’ in front of their names. The ‘L’ shows that they are found in nature. The letter ‘D’ in front of amino acids show that they are not found in nature and can be harmful to the body if taken. The exception is D-Phenylalanine, which the body can use.