Which protein contains tryptophan? An essential amino acid guide

December 6, 2025 •

4 min read

Tryptophan is an essential amino acid, meaning the body cannot produce it on its own and must obtain it through diet. Every protein contains tryptophan, but its concentration varies significantly between different food sources. Understanding which protein contains tryptophan is key to supporting vital bodily functions, including the production of serotonin and melatonin.

Quick Summary

This guide outlines the best dietary sources of tryptophan, including animal and plant-based proteins. It details how the body utilizes this essential amino acid to produce crucial brain chemicals like serotonin and melatonin, which influence mood and sleep. The article also compares tryptophan from food versus supplements.

Key Points

Tryptophan is an essential amino acid: Your body cannot produce it, so you must get it from your diet through protein-rich foods.
Sources include animal and plant proteins: Excellent dietary sources include turkey, chicken, cheese, eggs, fish, pumpkin seeds, soy products like tofu, and oats.
It's a precursor for serotonin and melatonin: Tryptophan is converted into serotonin, which regulates mood, and melatonin, which helps control sleep-wake cycles.
Combining with carbs can boost absorption: Consuming tryptophan with carbohydrates may increase its availability to the brain, indirectly supporting serotonin production.
Whole foods are safer than supplements: Obtaining tryptophan through a balanced diet is generally safer and more effective than using supplements, which have been linked to potential side effects.
Important for overall health: Adequate tryptophan intake is crucial for supporting cognitive function, emotional well-being, and sleep quality.

Understanding the Essential Amino Acid Tryptophan

Tryptophan is one of the nine essential amino acids that your body needs but cannot produce, making dietary intake crucial. While every protein source contains some amount of tryptophan, the quantity and bioavailability can vary widely. The body uses tryptophan for several critical metabolic processes beyond just building proteins. Most notably, it is the precursor for serotonin, a neurotransmitter that regulates mood, appetite, and sleep, and melatonin, a hormone that controls the sleep-wake cycle.

Animal-Based Protein Sources Rich in Tryptophan

Animal proteins are generally considered complete proteins, containing all nine essential amino acids, including tryptophan. Some of the most potent sources include:

Poultry: Turkey and chicken are well-known sources. A roasted chicken leg can provide a significant portion of the recommended daily intake. Many associate the post-Thanksgiving meal sleepiness with turkey's tryptophan content, but this is largely a myth, as other amino acids in the meal compete with tryptophan for absorption into the brain.
Dairy: Products like milk, cheese, and yogurt are excellent sources of tryptophan. A glass of milk or a serving of cheese can contribute substantially to daily intake. The casein protein in milk was actually the source from which tryptophan was first isolated.
Eggs: Whole eggs are packed with nutrients, including a good amount of tryptophan. Both the yolk and the white contain this amino acid.
Fish and Seafood: Many types of fish, such as salmon, tuna, and tilapia, contain high levels of tryptophan. Salmon, in particular, is also rich in omega-3 fatty acids, which are beneficial for overall health.
Red Meat: Beef and pork are solid sources of tryptophan, contributing to the essential amino acid intake.

Plant-Based Protein Sources Containing Tryptophan

For those following a vegetarian or vegan diet, numerous plant-based foods also contain tryptophan. While the concentration might differ from animal sources, a balanced plant-based diet can still provide adequate amounts.

Nuts and Seeds: Pumpkin seeds, sesame seeds, sunflower seeds, chia seeds, cashews, and peanuts are all excellent plant-based sources. Pumpkin seeds are particularly potent, providing a high concentration of tryptophan per serving.
Soy Products: Edamame, tofu, and raw soybeans are packed with tryptophan. Tofu, for example, offers a high dose per half-cup serving.
Legumes: Lentils, chickpeas, and beans also contribute to tryptophan intake. Chickpeas, for instance, are a decent source, particularly when incorporated into dishes like hummus.
Grains and Other Foods: Whole grains like quinoa and oats are notable sources. Quinoa is considered a complete protein and contains all essential amino acids. Even some less obvious foods like chocolate contain tryptophan.

Comparison: Tryptophan in Common Foods


Food Source	Tryptophan Content (mg)	Serving Size	Notes
Dried Egg White	1000 mg	100 g	Extremely high concentration due to dehydration.
Cheese (Parmesan)	560 mg	100 g	A rich, concentrated source.
Soybeans (Raw)	590 mg	100 g	High content, excellent for plant-based diets.
Chicken (Breast)	208-249 mg	100 g / 1 leg	Content can vary based on the specific cut and preparation.
Salmon	220 mg	100 g	Good source, also provides omega-3s.
Pumpkin Seeds	163 mg	1 ounce	Potent source in a small, dense serving.
Milk (Whole)	107 mg	1 cup	Convenient source, readily available.
Oats (Cooked)	147 mg	1 cup	High fiber and tryptophan content.

How to Maximize Tryptophan Absorption

Interestingly, eating tryptophan-rich foods alongside carbohydrates can increase the amount of tryptophan that reaches the brain. A meal high in carbohydrates triggers insulin release, which helps other amino acids get absorbed into muscle tissue. This leaves more tryptophan available to cross the blood-brain barrier. This explains why a large, carbohydrate-heavy meal might make you feel sleepy, though it's not solely the tryptophan in the turkey causing the effect.

The Role of Tryptophan in the Body

Serotonin and Mood Regulation: Tryptophan is vital for synthesizing serotonin, often called the "feel-good" neurotransmitter, which plays a major role in regulating mood and cognition. A balanced diet with sufficient tryptophan can support healthy serotonin levels.
Melatonin and Sleep: A healthy tryptophan intake supports the production of melatonin, the hormone that regulates the body's circadian rhythm and promotes sleep. Studies have shown that diets rich in tryptophan can help improve sleep quality.
Niacin Synthesis: Tryptophan is also a dietary source for niacin (Vitamin B3). The body can convert tryptophan into niacin, although this is a less efficient process than obtaining niacin directly from food.
Growth and Nitrogen Balance: As an essential amino acid, tryptophan is a fundamental building block for proteins and is necessary for tissue growth and maintaining nitrogen balance in adults.

Conclusion

Tryptophan is an essential amino acid found in a wide variety of protein-rich foods, including poultry, dairy, fish, nuts, and soy products. While the content varies, a balanced diet including both animal and plant sources can ensure sufficient intake to support mood regulation, sleep patterns, and overall health. Rather than relying on supplements, which can have potential side effects and are often unnecessary, prioritizing whole food sources of tryptophan is the safest and most effective strategy. Incorporating a mix of these foods into meals, perhaps paired with healthy carbohydrates, can maximize the benefits of this crucial nutrient for both physical and mental well-being.

Check out more research on tryptophan metabolism via the NIH.

Frequently Asked Questions

The idea that turkey makes you sleepy is largely a myth. While turkey contains tryptophan, other amino acids in a protein-rich meal compete with it to be absorbed into the brain. The drowsiness experienced after a large meal is more likely due to a combination of eating a large volume of food and consuming carbohydrates, which cause a release of insulin that helps clear competing amino acids from the bloodstream.

Tryptophan in food is naturally occurring and generally safe, as it is balanced by other amino acids. Supplements, however, provide a concentrated, isolated dose. Some tryptophan supplements were linked to a rare illness called eosinophilia-myalgia syndrome (EMS) in the late 1980s, though this was later attributed to a contaminated batch from a single manufacturer. It is safer and more effective to get tryptophan from whole foods.

Yes, because tryptophan is an essential amino acid required for producing serotonin and niacin, a deficiency can lead to significant health problems. Symptoms of deficiency can include depression, anxiety, irritability, sleep disturbances, and in severe cases, the disease pellagra.

Many plant-based foods, such as nuts, seeds, and soy products, are excellent sources of tryptophan. While some plant-based proteins like quinoa and soy are considered 'complete' because they contain all essential amino acids, others may need to be combined to ensure a balanced intake of all essential amino acids.

Tryptophan is the necessary precursor for serotonin production, but consuming it does not guarantee a direct increase in serotonin. The conversion is influenced by various factors, including the presence of other amino acids and carbohydrates. A balanced diet with sufficient tryptophan intake, however, provides the body with the necessary building blocks for healthy serotonin synthesis.

To naturally boost your tryptophan intake, focus on incorporating a variety of protein-rich foods into your diet. This can include poultry, dairy, fish, eggs, and a wide array of plant-based options like seeds, nuts, and soy products. Pairing these proteins with healthy carbohydrates can also enhance tryptophan absorption into the brain.

It is highly unlikely to overdose on tryptophan by consuming it through natural food sources. Your body is able to regulate the absorption and utilization of amino acids from food effectively. Overdose concerns are primarily associated with the use of concentrated supplements.