Essential amino acid
Tryptophan
The scarcest one. Precursor to serotonin and melatonin.
4 mg/kg/day — the smallest of the nineAbout 280 mg a day at 70 kg
What it builds
Tryptophan has the smallest requirement of the nine by a wide margin, which sounds reassuring until you notice it is also the rarest in food. Those two facts roughly cancel out.
It is the raw material for serotonin, and downstream of that for melatonin, which is why it appears in every article about mood and sleep. It is also a precursor to niacin (vitamin B3), so a slice of your intake is spent on vitamin synthesis rather than on building protein.
Where tryptophan actually comes from
Gram for gram, pumpkin seeds are the densest everyday plant source in the database. A realistic handful is a small portion next to a fillet of fish, which is why the ranking below reads the way it does.
Ranked by a realistic portion rather than per 100 g, because nobody eats 100 g of pumpkin seeds. Figures are digestibility-adjusted, so these are the amounts the app credits you with, not the amounts printed on the packet. Computed live from the 72 foods in the AminoLens recommender pool.
All foods
Every food in the pool, animal and plant.
| Food | Portion | Per portion |
|---|---|---|
| Chicken breast | 120 g breast | 413 mg |
| Lamb leg | 120 g | 375 mg |
| Turkey breast | 120 g | 327 mg |
| Chicken thigh | 120 g | 318 mg |
| Pork tenderloin | 120 g | 314 mg |
| Haddock | 120 g fillet | 296 mg |
Plant-based only
Vegan foods only. The list most people actually need.
| Food | Portion | Per portion |
|---|---|---|
| Soybeans | 120 g cooked | 264 mg |
| Extra-firm tofu | 150 g | 184 mg |
| Tempeh | 100 g | 177 mg |
| Firm tofu | 150 g (half a block) | 168 mg |
| White beans | 150 g cooked | 141 mg |
| Pumpkin seeds | 30 g (small handful) | 138 mg |
Signs you might be short
Genuine tryptophan deficiency is rare and we are not going to imply otherwise. Low intake correlates with low mood and poor sleep in research settings, but that is a finding about populations, not a diagnosis for you, and we intend to stay on the right side of that line.
Realistically, tryptophan becomes the limiting line mainly on diets low in total protein, rather than on diets that are merely unbalanced.
Pairs well with
Most balanced diets cover it without effort. It becomes the binding constraint mainly when total protein is low, so the fix is usually more protein rather than different protein.
See your tryptophan coverage
Photograph a meal and watch where the protein actually goes.
Analyse a meal