Tryptophan: Food Sources & Daily Intake

Tryptophan is an essential amino acid best known as the body’s starting material for two key signaling molecules: serotonin, a brain chemical tied to calm mood and well-being, which the body then converts into melatonin, the hormone that sets the sleep–wake clock. Tryptophan has a third, quieter job — it is the only amino acid the body can turn into the B-vitamin niacin (vitamin B3). Because it is essential, the body cannot make it, so it must come from food. It is also the rarest amino acid in protein, which is why the daily requirement is the smallest of all the essentials. The richest sources are concentrated animal proteins — poultry, fish, eggs and hard cheese — along with pumpkin and sesame seeds, peanuts, oats and legumes. The table below shows grams of tryptophan per 100 g of food; there is no FDA Daily Value for individual amino acids, so amounts are absolute.

Table of Contents

1. How to Read These Tables
2. Recommended Intakes & Upper Limits
3. Bioavailability & Absorption
4. Cooking & Storage
5. Vegetarian & Vegan Sources
6. Who Needs to Pay Attention
7. Data Sources & References
8. Connections
9. Featured Videos

How to Read These Tables

• Essential amino acid. Your body cannot synthesize tryptophan, so a regular dietary supply matters. The nine essential amino acids must come from food; the other eleven the body can build itself. Tryptophan is the least abundant of the nine, so even protein-rich foods carry only modest amounts.
• Grams per 100 g, not %DV. There is no FDA Daily Value for individual amino acids, so this table reports the absolute grams per 100 g of food and ranks foods by that. A typical serving is shown beside each food.
• Complete vs incomplete protein. Animal foods are “complete” — they carry all the essential amino acids in good proportion. Most single plant foods are lower in one or two; eating a variety of legumes, grains, nuts and seeds across the day covers the gaps.

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Recommended Intakes & Upper Limits

Your personal target depends on age, sex and pregnancy. The Daily Value used for the %DV column above is a single label figure; the table below is the age-specific guidance.

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Bioavailability & Absorption

Tryptophan from food is well absorbed as part of dietary protein, but getting it into the brain — where it becomes serotonin — is a separate, competitive step. Tryptophan is a large amino acid, and it has to share the same transporter into the brain with several other large amino acids (leucine, isoleucine, valine, phenylalanine, tyrosine). After a high-protein meal those competitors flood the bloodstream and crowd tryptophan out, so brain tryptophan can actually fall. A carbohydrate-rich meal does the opposite: it raises insulin, which pulls the competing amino acids into muscle and leaves tryptophan with a clearer path into the brain. This is the kernel of truth behind the “turkey makes you sleepy” idea — but the popular version is a myth. Turkey is not unusually high in tryptophan (chicken, fish and cheese are similar or higher), and because turkey is mostly protein it actually supplies the competing amino acids too. The post-Thanksgiving drowsiness owes far more to the big carbohydrate-heavy meal, alcohol and the size of the feast than to turkey itself.

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Cooking & Storage

Amino acids are stable to ordinary cooking — tryptophan is not destroyed by normal heat, and cooking actually makes protein easier to digest. No special handling is needed. (One footnote for the curious: tryptophan can be partly lost during industrial acid hydrolysis used in the laboratory to measure protein, which is why some older food tables under-report it — but that is an analysis artifact, not something that happens on your stove.)

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Vegetarian & Vegan Sources

Plant-based eaters can reach the tryptophan target comfortably, because the daily requirement is small and several plant foods are genuinely tryptophan-dense. The standout plant sources are pumpkin and sesame seeds, peanuts, oats and legumes (lentils, beans, chickpeas). Eating a variety across the day — seeds and legumes alongside whole grains — supplies all the essential amino acids in good balance. Because tryptophan competes with other amino acids to reach the brain, plant meals that pair these foods with wholesome carbohydrates (oats, fruit, whole grains) can also be a gentle, food-based way to support an evening wind-down.

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Who Needs to Pay Attention

Outright tryptophan deficiency is rare in anyone eating enough total protein. The groups who should pay attention are those with very low overall protein intake — some older adults, people recovering from illness, and poorly planned very-low-calorie or restrictive diets. Because tryptophan is the body’s backup route to making niacin (vitamin B3), a diet that is short on both niacin and tryptophan can contribute to pellagra (the classic niacin-deficiency disease of diarrhea, dermatitis and dementia) — historically seen where corn, which is low in both, dominated the diet. A separate caution applies to supplements: isolated tryptophan or 5-HTP raises serotonin, so combining them with serotonin-active medicines (such as SSRIs/SNRIs antidepressants, certain migraine drugs, or MAO inhibitors) can push serotonin too high. Anyone on those medicines should not add tryptophan or 5-HTP supplements without medical advice; getting tryptophan from ordinary food is not a concern.

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Data Sources & References

• NIH MedlinePlus — Amino acids
• Linus Pauling Institute — protein and essential amino acids
• PubMed — tryptophan, serotonin and brain uptake (large neutral amino acids)
• PubMed — tryptophan, niacin synthesis and pellagra

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Connections

• Tryptophan (Main Page)
• Tryptophan Benefits
• Tryptophan History
• All Amino_Acids
• Tyrosine
• Phenylalanine
• Vitamin B3 (Niacin)

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