Tryptophan
Tryptophan is the essential amino acid the body turns into serotonin, melatonin and niacin. Adults need about 4 mg per kilogram of body weight a day, the smallest amount of the nine.
4 mg per kg of body weight a day
280 mg a day for a 70 kg adult (WHO)
Upper limit · none set by the EU or the US
- Most per 100 g 0.57g Pumpkin seeds
- Main sources Cheese, meat and fish then seeds, nuts and oats
- Becomes Serotonin then melatonin at night
- Niacin from it 60 : 1 mg of tryptophan per mg of niacin
Daily amount: WHO, FAO and UNU 2007 report on protein and amino acid requirements. Food figures per 100 g from USDA FoodData Central, only for foods with a Caltide calorie page.
Foods High in Tryptophan
Ranked per 100 g, with what a usual portion gives, limited to 3 foods per category. Foods with a Caltide calorie page link to it.
P
Pumpkin seeds
0.82 g in 1 cup
0.57g / 100 g
M
Mozzarella
0.64 g in 1 ball
Nutrition facts
0.52g / 100 g
S
Soy nuts
0.49 g in 1 cup
0.51g / 100 g
C
Crimini mushroom
0.5g / 100 g
P
Pioppini mushroom
0.49g / 100 g
W
White button mushrooms
0.48g / 100 g
B
Bacon
Nutrition facts
0.45g / 100 g
C
Chia seeds
0.052 g in 1 tablespoon
Nutrition facts
0.44g / 100 g
G
Gruyère
0.42g / 100 g
M
Mixed seeds
0.53 g in 1 cup
0.36g / 100 g
F
Fontina
0.36g / 100 g
T
Tilsit
0.074 g in 1 slice
0.35g / 100 g
What Is Tryptophan?
Tryptophan is one of the nine essential amino acids: the body cannot make it, so every gram has to come from food protein or a supplement. It is also the least plentiful of the nine in most food proteins.
What the Body Makes From Tryptophan
Most tryptophan is built into protein, in muscle, enzymes and every other tissue. A small share takes one of three other paths.
Serotonin. Two enzyme steps turn tryptophan into serotonin, a messenger in the brain and, in far larger amounts, in the gut, where most of the body's serotonin is made. The step in between is 5-hydroxytryptophan, sold as the supplement 5-HTP.
Melatonin. In the pineal gland, serotonin is turned into melatonin when it gets dark. Melatonin is the hormone that signals night to the rest of the body.
Niacin. The liver can build niacin (vitamin B3) from tryptophan, at about 60 mg of tryptophan for each 1 mg of niacin. Diets very low in both, once common where maize was the staple food, caused pellagra. The conversion also needs vitamin B6, riboflavin and iron.
Why More Tryptophan Does Not Mean More Serotonin
To reach the brain, tryptophan shares one transporter with several larger amino acids, including leucine, valine and tyrosine. A high protein meal brings all of them at once, and tryptophan, the scarcest, gets a small share of the seats. So a tryptophan-rich food does not reliably raise brain serotonin.
Turkey, Tryptophan, and Sleepiness
Turkey is blamed for sleepiness after big holiday meals, but in the Caltide food library roast turkey has 0.31 g of tryptophan per 100 g. Mozzarella has 0.52 g and chia seeds 0.44 g, and baked cod 0.26 g. Turkey is an ordinary source, not an unusual one.
The figures put the daily need in perspective too. A 100 g serving of roast turkey gives about 307 mg, more than the 280 mg a 70 kg adult needs in a whole day. Anyone eating enough protein almost always eats enough tryptophan.
Who Is Most Likely to Be Low in Tryptophan
Shortfalls come with low protein intake overall, as in severe undernutrition, rather than from avoiding one food. Hartnup disease, a rare inherited condition, blocks the absorption of tryptophan and several other amino acids in the gut and kidneys, and can cause pellagra-like skin rashes.
Compare foods in the food library, or see how tyrosine feeds a different set of brain messengers.
How Much Tryptophan You Need
The WHO figure is per kilogram of body weight, so the daily amount rises with body weight.
| Body weight | A day |
|---|---|
| 50kg | 200mg |
| 60kg | 240mg |
| 70kg | 280mg |
| 80kg | 320mg |
| 90kg | 360mg |
| 100kg | 400mg |
Tryptophan Supplements
Food is the main source, but supplements are a source too. Two kinds are sold, and they are not interchangeable.
L-Tryptophan
The same amino acid as in food protein. The body can build protein, serotonin or niacin from it. Protein powders and essential amino acid blends contain it too, in smaller amounts.
5-HTP
5-hydroxytryptophan, usually extracted from the seeds of the African plant Griffonia simplicifolia. It is one step past tryptophan on the way to serotonin, so it cannot become protein or niacin, and it does not count toward the tryptophan requirement.
The 1989 L-Tryptophan Recall
In 1989 an outbreak of eosinophilia-myalgia syndrome, a serious muscle and blood disorder, was traced to contaminated L-tryptophan from one manufacturer. More than 1,500 people fell ill, and the US restricted sales for years. The outbreak was linked to impurities in that maker's product rather than to tryptophan itself, and it is why purity matters for this supplement.
Medicines That Interact With Tryptophan
- Antidepressants (SSRIs, MAO inhibitors)together with tryptophan or 5-HTP they can raise serotonin too far
- Other serotonin drugssuch as triptans for migraine, tramadol and St. John's wort
Ask a doctor or pharmacist before combining a supplement with a medicine.
Tracking Tryptophan in Caltide
- Logged automaticallyCaltide adds up the tryptophan in every food you log and in the supplements you tick off, and shows it in the Nutrition tab against the WHO amount for your body weight.
- Set your weightThe requirement is per kilogram, so Caltide needs your weight to show a percentage. Without it you see the amount only.
Tryptophan Sources and References
The figures and claims on this page are checked against these sources. Food amounts come from USDA FoodData Central.
Questions About Tryptophan
Adults need about 4 mg per kilogram of body weight a day, according to the WHO, FAO and UNU 2007 report. That is about 280 mg for a 70 kg adult, the smallest requirement of the nine essential amino acids.
In the Caltide food library, pumpkin seeds: 0.57 g per 100 g. Mozzarella (0.52 g) and Soy nuts (0.51 g) come next.
Not on its own. Roast turkey has 0.31 g of tryptophan per 100 g in the Caltide food library, less than mozzarella (0.52 g) and in the same range as other meat and fish, such as cod (0.26 g).
Yes. The liver can make niacin (vitamin B3) from tryptophan, at about 60 mg of tryptophan for 1 mg of niacin. That is why niacin needs are given in niacin equivalents, which count both.
No. L-tryptophan is the amino acid found in food protein. 5-HTP (5-hydroxytryptophan) is the next step on the way to serotonin, so the body cannot use it to build protein or make niacin.
Only with a doctor's advice. Tryptophan and 5-HTP raise serotonin, and combining them with SSRIs, MAO inhibitors or other drugs that raise serotonin can cause serotonin syndrome.
Usually, yes. Seeds, nuts, oats, beans and tofu all supply it, and someone eating enough protein from varied plants reaches 4 mg per kilogram without trying.
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