Functions Of Amino Acids And Good Food Sources by Jane Thurnell-Read

When we eat protein foods the body breaks them down into amino acids. The amino acids are then rebuilt into the proteins that the human body needs.

Different amino acids perform different functions in the body. Animal proteins include all amino acids, but there are also many excellent non-animal sources of protein.

Alanine
Involved in the metabolism of tryptophan and the vitamin B6.
Good Food Sources: Beans, nuts, seeds, soya, brewer's yeast, brown rice bran, corn, legumes, whole grains.

Arginine
Stimulates human growth hormone which stimulates defence function; accelerates wound healing; detoxifying ammonia; normal sperm count; glucose control mechanism in blood; enhances fat metabolism; involved in insulin production; arthritis; inhibition of tumour development; premature ageing; overweight; fatigue; memory.
Good Food Sources: Peanuts, tofu, pumpkin seed, almonds, sunflower seeds, Brazil nuts, chocolate, cereals

Asparagine
Required by the nervous system and in the synthesis of ammonia.
Good Food Sources: Asparagus, potatoes, legumes, nuts, seeds, soya, whole grains

Aspartic Acid
Protects liver; detoxification of ammonia; promotes uptake of trace elements in the gut; involved in the energy cycle; involved in transportation of magnesium and potassium.

Cystine/ Cysteine
Part of insulin molecule; heavy metal chelator; psoriasis; eczema; tissue healing after surgery.
Good Food Sources: Soya protein, almonds, sesame seeds, walnuts.

Glutamic Acid/Glutamate
Precursor of proline, ornithine, arginine and polyamines; a stimulatory neurotransmitter; can be converted in body into GABA (inhibitory neurotransmitter); nearly all excitatory neurons in the CNS and possibly half of the synapses in the brain communicate via glutamate; visual adaptation to light and dark; many epileptics have increased levels of glutamic acid; part of the acute reaction to withdrawal from drug addiction includes increase production of glutamate.

Glutamine
Dominant amino acids in cerebro-spinal fluid and serum; passes through blood/brain barrier; powerful "brain fuel"; gives rise to GABA which is a calming agent; helps maintain body's nitrogen level; used in production of other non-essential amino acids; protects from alcohol; reduces desire for alcohol and sometimes sugar; heals peptic ulcers; depression; blunts carbohydrate craving; hypoglycaemia; schizophrenia; senility; fatigue; memory improvement; concentration; smoking.

Glycine
Can be synthesised from other amino acids (serine and threonine); acts as an inhibitory neurotransmitter; assists in manufacture of DNA, glycerol, phospholipids, collagen, glutathione and cholesterol conjugates; essential for one of key liver detoxification pathways; stimulates secretion of glucagons; in spinal cord (inhibitory action) and in retina; Parkinson’s disease; low levels often found in manic-depressives and epileptics. People with motor neurone disease may have impaired glycine metabolism and have high levels of glycine in the blood.

Histidine
Metabolised into histamine which is important for smooth muscle function and contraction and expansion of blood vessels; sexual arousal; auditory nerve function; stimulates production of red and white blood cells; schizophrenia; protects against radiation damage; chelates toxic metals; rheumatoid arthritis; digestive tract ulcers; nausea during pregnancy; hearing problems; allergies; anxiety; low stomach acid; smoking.
Good Food Sources: Soya protein concentrate, peanuts, tofu, sunflower seeds.

Isoleucine
Chronically sick; formation of haemoglobin; energy production; reduces tremors and twitching in animals; body building.
Good Food Sources: Soya protein concentrates, soya flour, tofu, peanuts, almonds, pumpkin seeds, sunflower seeds.

Leucine
Chronically sick; essential for growth; wound healing of skin and bones; energy production; Parkinson’s disease; enhances effects of endorphins.
Good Food Sources: Soya protein concentrate, soya flour, peanuts, tofu, almonds, pumpkin seeds.

Lysine
Often low in vegetarian diets; important for children's growth and development; involved in synthesis of carnitine, so important in fat metabolism; formation of antibodies; dietary deficiency leads to increased calcium excretion; herpes simplex; concentration; fatigue; dizziness; anaemia; visual disorders; nausea; hypoglycaemia.
Good Food Sources: Soya protein concentrate, soya flour, tofu, parsley, quinoa, whole-wheat flour.

Methionine
Antioxidant preventing free radical damage; helps produce choline, adrenaline, lecithin and B12; assists gallbladder function; precursor of taurine, cystine and cysteine. Heavy metal and histamine detoxifier; strengthens hair follicles; detoxifies liver; affects selenium bio-availability; arthritic and rheumatoid symptoms; detoxification; antioxidation; retards cataracts; Parkinson’s disease; schizophrenia; gallbladder problems resulting from use of contraceptive oestrogen; poor skin tone; hair loss; anaemia; retarded protein synthesis; atherosclerosis; herpes; memory; premature ejaculation.
Good Food Sources: Brazil nuts, sunflower seeds, sesame seeds, beans, lentils, soya beans, quinoa.

Phenylalanine
Precursor of tyrosine and therefore dopamine, norepinephrine (noradrenaline) and epinephrine (adrenaline), so affects heart rate, blood pressure, oxygen consumption, blood sugar levels, fat metabolism; important for brain; necessary for thyroid; shortage predisposes children to eczema; weight control; antidepressant; pain killer; MS; Parkinson’s disease; memory; concentration and mental alertness; rheumatoid arthritis; vitiligo; emotional disorders; circulatory problems; drug addiction; tremors.
Good Food Sources: Soya protein concentrate, soya flour, tofu, peanuts, almonds, sesame seeds, sunflower seeds.

Proline
Production of collagen and cartilage.

Serine
Can be made in human body from glycine; used to make substances such as choline, phospholids, phosphotidylserine; present in all cell membranes; plays a key role in membrane stability.
Good Food Sources: Gluten, soya, peanuts.

Threonine
Necessary for formation of teeth enamel protein, elastin and collagen; minor role controlling fat build up in liver; precursor of glycine and serine; immune stimulating as promotes thymus growth and activity; digestive and intestinal tract functioning; indigestion; malabsorption; irritability; personality disorders.
Good Food Sources: Soya protein concentrate, soya flour, tofu, peanuts, almonds.

Tryptophan
Synthesis of vitamin B3; precursor of serotonin; mood stabiliser; vascular migraine, anti‑depressant; weight control; sleep enhancer; menopausal depression; pain killer; restless leg syndrome; rheumatoid arthritis; tardive dyskinesia; mental disturbances, depression, brittle finger nails; poor skin colouring and tone; indigestion; carbohydrate craving. May aggravate bronchial asthma and lupus.
Good Food Sources: Soya protein concentrate, soya flour, tofu, almonds, peanuts, pumpkin seeds, sesame seeds, tahini, almonds, sunflower seeds.

Tyrosine
Derived from phenylalanine; precursor of thyroid hormones, dopa, dopamine, norepinephrine and epinephrine; aids normal brain function; Parkinson’s disease; depression; increasing brain neurotransmitter levels; alleviating hay fever and grass allergies; drug addiction; tremors; low blood pressure.
Good Food Sources: Soya protein concentrate, soya flour, tofu, almonds, pumpkin seeds, peanuts, peanut butter.

Valine
Helpful in treating addictions; deficiency may affect myelin covering of nerves; energy; muscle building and c‑ordination; liver and gallbladder disease; mental function; nervousness; poor sleep patterns; excess gives skin crawling sensations and hallucinations.
Good Food Sources: Soya protein concentrate, soya flour, tofu, pumpkin seeds, peanuts.

Copyright Jane Thurnell-Read 2009