Tyrosine: What It Makes, Indian Food Sources and the Stress Trials

Tyrosine is an amino acid with two supply lines. Your liver makes it from phenylalanine, an essential amino acid, and your food delivers it ready-made in every protein you eat. Because one can stand in for part of the other, ICMR-NIN's 2020 recommendation covers both together: 38 mg of phenylalanine plus tyrosine in each gram of dietary protein, close to 25 mg per kg of body weight a day for an adult. The body turns tyrosine into dopamine, noradrenaline, adrenaline, thyroid hormone and the pigment melanin. You will find the other amino acids in the handbook's proteins and amino acids section.

What is tyrosine, and where does it come from?

It is one of the twenty amino acids from which body proteins are built, and it is not on the list of nine that ICMR-NIN's Dietary Guidelines for Indians, 2024, call essential, because the body can synthesise it. The starting material is phenylalanine. A 2021 review in Nature Reviews Disease Primers describes the step: the enzyme phenylalanine hydroxylase adds a hydroxyl group to phenylalanine, predominantly in the liver and also in the kidneys, and the product is tyrosine.

That dependence is why nutrition bodies treat the two as a pair, the aromatic amino acids. Tyrosine eaten in dal, milk or egg lowers the amount of phenylalanine that has to be converted. When a diet contains no tyrosine at all, phenylalanine must meet the whole need. The page on non-essential amino acids explains the wider group that tyrosine belongs to.

What does the body make from tyrosine?

Apart from its place in protein, tyrosine is the precursor of three families of compounds. The same review lists them: the neurotransmitters dopamine, adrenaline and noradrenaline, known together as catecholamines; thyroxine, made in the thyroid gland; and melanin, made in the pigment cells of skin and hair. Whatever is left over is broken down and used as fuel.

In the thyroid, the tyrosine is not free. The gland attaches iodine to tyrosine units that are already part of a large protein, thyroglobulin, and then joins pairs of them to form the hormones T4 and T3, as a review in the journal Thyroid sets out. The supply that limits this process in practice is iodine, not tyrosine. The handbook's page on thyroid hormones covers the tests and the Indian figures.

How much tyrosine do you need?

No body sets a requirement for tyrosine alone; the figure is always for phenylalanine and tyrosine combined. By the WHO/FAO/UNU 2007 values, as amended in the FAO's 2013 report on protein quality, an adult needs 25 mg of the pair per kg of body weight a day. For a 65 kg man that comes to about 1,625 mg and for a 55 kg woman about 1,375 mg. Infants and children need more per kg because they are growing, as the table shows.

The Indian recommendation and the plate behind it

ICMR-NIN's 2024 guidelines carry the institute's 2020 recommendation for each essential amino acid, and the line for phenylalanine plus tyrosine reads 38 mg per gram of protein. Beside it they print what their model day supplies: 87.9 mg per gram from the vegetarian My Plate for the Day and 89.6 mg from the non-vegetarian one. The full 2020 report's chapter on amino acids could not be opened for this entry, so no Indian figure per kg, and none for pregnancy or lactation, is given here.

What you plan for is protein, and tyrosine comes with it. The adult allowance in ICMR-NIN's 2020 report is 0.83 g of protein per kg a day, printed as 54 g for a 65 kg man and 46 g for a 55 kg woman. NNWA's protein calculator works out the figure for your own weight and activity.

Tyrosine in Indian foods

Milk protein is the richest common source. The Indian Food Composition Tables 2017 give tyrosine as grams in 100 g of protein: 5.48 for whole cow's milk, 4.86 for buffalo milk and 5.36 for paneer. Raw milled rice is next at 4.36. Whole egg has 3.93, skinless chicken breast 3.89 and groundnut 3.86. Pulses sit near 3, with moong dal at 2.95 and rajma at 3.12, and whole-wheat atta is lowest at 2.10. Even atta, once its 5.03 g of phenylalanine is added, clears the combined pattern of 3.8 g.

Portions are raw weights and the household measures are rough. To see which foods carry the most protein in the first place, use NNWA's ranking of protein in Indian foods; the pages for paneer in the food tables and cow's milk give the full nutrient panels of the two richest vegetarian sources. Cereal-based diets do have a weak point, but it is lysine, which cereals lack, and not the aromatic pair.

Is tyrosine ever essential?

Yes, in one inherited condition, and it becomes more important whenever phenylalanine intake is restricted. In phenylketonuria the enzyme that converts phenylalanine does not work, so the body cannot make its own tyrosine and depends entirely on what the diet supplies. Whether extra tyrosine on top of that helps is a separate question: a Cochrane review updated in 2021 found three suitable trials with 56 participants and could make no recommendation.

The relationship has also been measured in healthy Indians. Researchers in Bengaluru fed 32 men diets that contained no tyrosine and found that they then needed 38 mg of phenylalanine per kg a day, well above the 25 mg that covers both amino acids on an ordinary diet. The study, in the American Journal of Clinical Nutrition in 2006, is small, but it shows the sparing effect in numbers.

Does tyrosine help under stress or sharpen thinking?

The trials suggest a small, short-lived effect on mental tasks performed under acute stress, and little else. The idea is that severe stress uses up catecholamines in the brain faster than they are made, and that extra precursor might keep supply going. A 2015 review in the Journal of Psychiatric Research concluded that tyrosine does seem to improve cognitive performance in short-term stressful or mentally demanding situations, that its promise for treating clinical disorders is limited, and that its effect on physical exercise is minimal.

A second 2015 assessment, in Military Medicine, graded the trials. It found 10 randomised and 4 other controlled trials, made only a weak recommendation in favour of tyrosine for cognitive stress, made none for physical performance, and judged the evidence insufficient for confident advice. The individual experiments are small and unusual: 19 volunteers sitting in cold water did better on a memory task after tyrosine, and 21 cadets on a week-long combat course did better on memory and tracking tasks, with no change in mood.

Age may change the answer. In a 2018 placebo-controlled study of 24 healthy adults aged 61 to 72, tyrosine did not improve response inhibition, and the older the participant, the more it worsened one measure of it. None of these trials tested students before examinations, office workers under deadline or people with long-term stress, and none ran for months. The handbook's page on cortisol deals with the stress hormone itself.

Does a tyrosine supplement help the thyroid?

No trial that could be verified for this entry shows that tyrosine capsules raise thyroid hormone or correct an underactive thyroid. The claim rests on chemistry alone: thyroid hormone is built on tyrosine, so more tyrosine is assumed to mean more hormone. The gland, however, works on tyrosine already inside thyroglobulin, and ordinary food supplies the amino acid several times over. Hypothyroidism is diagnosed with blood tests and managed by a doctor; the guide to the hypothyroidism diet in India explains what food can and cannot do.

A worked example: a student before examinations

The person here is invented for the arithmetic. A 23-year-old vegetarian student in Kolkata, 65 kg, is preparing for professional examinations and is thinking of buying tyrosine capsules for concentration. His combined requirement for phenylalanine and tyrosine is 25 mg per kg, about 1,625 mg a day. His food for the day is cooked from 125 g of atta, 125 g of rice, 45 g of moong dal and 40 g of toor dal, raw weight, with 300 g of milk as curd and tea.

Using IFCT 2017, the day holds 52.3 g of protein. Tyrosine comes to about 1,763 mg: 278 mg from the atta, 431 from the rice, 317 from the moong dal, 201 from the toor dal and 536 from the milk. Phenylalanine adds about 3,121 mg. Together that is 4,884 mg, or 93.3 mg per gram of protein against the pattern of 38, and three times his requirement before digestibility is counted. The capsule would add to a supply that is already full, and the trials offer no evidence about examinations. Sleep and regular meals are the better use of his money.

Common mistakes and myths about tyrosine

The first mistake is assuming that a precursor works like a tap, so that more tyrosine must mean more dopamine, more drive and a faster metabolism. The reviews found benefit only where stress had temporarily run supplies down, and one trial in older adults found harm on a task. The second is reading military experiments in cold water as evidence for a desk job. The third is expecting vegetarian diets to be short of tyrosine, when milk and paneer are its richest common sources.

Tyrosine supplements in India: FSSAI's rules

FSSAI's regulations on health supplements and nutraceuticals, made in 2016, name L-tyrosine and acetyl-L-tyrosine in the schedule of amino acids that such products may contain. The schedule sets no amount. Every pack must state the quantity of the nutrient present, carry the words HEALTH SUPPLEMENT and the warning NOT FOR MEDICINAL USE, tell the buyer not to exceed the recommended daily usage, and say that the product is not a substitute for a varied diet. The label and advertising may not claim that it prevents, treats or cures a disease.

Cautions, medicine interactions and when to see a doctor

ICMR-NIN sets no upper limit for tyrosine, and this entry gives no dose. The clearest warning concerns monoamine oxidase inhibitors, a class of antidepressant. The prescribing information for phenelzine tells patients not to take L-tyrosine or phenylalanine, in the same sentence as stimulant drugs, because of the risk of a hypertensive crisis. Anyone on a medicine of this class should not take tyrosine.

Levodopa, the main medicine for Parkinson's disease, uses the same carrier in the gut and at the brain as the large neutral amino acids, tyrosine among them, which is why doctors manage its doses around meals and protein intake. With thyroid medicine the concern is different: tyrosine is the building block of the hormone being replaced, the effect of adding it has not been established, and the decision belongs to the doctor who adjusts the dose from blood tests. Never stop or reduce a prescribed medicine in favour of a supplement.

See a doctor if you have a pounding headache, palpitations or a sharp rise in blood pressure after taking any supplement, and take the pack with you. People with an overactive thyroid or high blood pressure should ask their own doctor before using tyrosine, as a precaution; no trial read for this entry settles the question. No food or supplement cures a thyroid or mood disorder.

Learning to read supplement claims at NNWA

Reading a supplement label against the evidence is a skill taught in NNWA's courses, including Sports Nutrition and the Diploma in Nutrition. NNWA is a private skill academy based in Kolkata, with online classes in English and Hindi. Its courses, none of them a degree or a dietitian qualification, prepare people to coach healthy clients and to send medical questions, medicine interactions among them, to a doctor.