What is Tryptophan? Why You Should Love This Amino Acid

What is Tryptophan? Why You Should Love This Amino Acid

When people talk about how your food can help you feel better and build muscle, most articles, videos, and even books focus on the big picture. They’ll talk about the benefits of eating protein and how you need to eat adequate amounts of vitamins and minerals, but few dive into the nitty-gritty of protein to talk about amino acids. 

Amino acids are essential to your health and if there’s one you need to know about, it’s tryptophan. 


What is tryptophan? 

As I touched on above, tryptophan is an essential amino acid that’s used by the body for muscle growth and to produce niacin, which in turn produces serotonin. There are actually two types of tryptophan: L-tryptophan and D-tryptophan, but the differences are largely unimportant for the layperson when it comes to benefiting from tryptophan. The recommended daily intake of tryptophan is 1.8mg per pound, so around 250mg a day for a 140lbs person. 


How does tryptophan affect my physical health? 

Tryptophan is best known for its role in assisting with muscle growth and nitrogen balance, but it also plays other key roles in our physical health. 

Recent studies have found that it can play a role in the therapy of cardiovascular disease, as well as chronic kidney disease, multiple sclerosis, and inflammatory bowel disease. It’s also been seen to have the potential to contribute to the therapy of cognitive issues such as autism, sleep, social function, and other cognitive functions. 

It’s also believed that tryptophan can facilitate the diagnosis of cataracts, colon and rectal diseases, and diabetic nephropathy. 

To return to its muscle-building qualities, tryptophan became popular for those looking to build muscle because it has been seen to increase lean muscle mass and decrease body fat, though it’s worth noting that most studies on this have been on rodents. 


How does tryptophan affect my mental health? 

Where tryptophan is particularly noteworthy is in its use in the production of serotonin – in fact, it’s the sole precursor of serotonin. Serotonin is a neurotransmitter that assists in mood stabilization, as well as other functions such as digestion and sleeping. Low levels of serotonin are strongly linked to anxiety, depression, and SAD (Seasonal Affect Disorder.) 

Research has found that withdrawal of tryptophan (called tryptophan depletion) can incite depressive periods, though interestingly, more so in those that have already experienced depression or anxiety in the past.  

Studies have seen that loading tryptophan in the diet increases the rate of serotonin synthesis in the brain, which in turn improves mood stabilization and decreases incidences of depression and anxiety. 

Where can I find tryptophan? 

Tryptophan is found in protein, so naturally, it’s found in protein-rich foods such as: 

  • Chicken & turkey breast (687mg in a 6oz breast) 

  • Lean pork (409mg per 100g) 

  • Tofu (592mg per cup of uncooked firm tofu) 

  • Salmon (570mg per 6oz fillet) 

  • Lean, boneless, almost fatless rib-eye beef steak (378mg per 100g) 

  • Mozzarella (603mg per 100g) 

  • Pumpkin seeds (576mg per 100g) 

  • Parmesan (560mg per 100g) 

  • Chia seeds (436mg per 100g) 

  • Tahini (393mg per 100g) 

  • Sesame seeds (388mg per 100g) 

  • Cheddar cheese (320mg per 100g) 

  • Montery cheese (315mg per 100g) 

It’s also found in high protein vegetable sources, such as broccoli (30mg per 1 cup chopped but uncooked), but in much smaller amounts: 

  • Seaweed (929mg per 100g) 

  • Sweet peppers (229mg per 100g) 

  • Leeks (117mg per 100g) 

  • Spinach (100mg per 100g) 

  • Potatoes (98mg per 100g) 

You’ll even find traces of it in herbs and spices like paprika (70mg per 100g), onion powder, black pepper, cinnamon, fresh basil, and dill. 


Are tryptophan supplements safe? 

Tryptophan supplements simply aren’t necessary – it can be found in any protein source, so it’s best to find it in your diet either through sources like those listed above or through a protein powder. L-tryptophan products aren’t recommended, and are generally only considered safe to take for 3 weeks, and are linked to side effects such as drowsiness, stomach pain, vomiting, and more. 

Tryptophan sourced through your food is 100% safe to take, rely on the foods you eat (or drink) for your tryptophan intake. 


Tryptophan is incredibly beneficial to your health, and since it’s not easy to eat it as a supplement, it’s important to make sure your diet is rich in this essential amino acid. Not only is it a great way to support your muscular fitness, but your mental health, too. 



Dr. Nancy Rahnama, MD, ABOM, ABIM, is a medical doctor board certified by both the American Board of Obesity Medicine and the American Board of Internal Medicine. Her specialty is Clinical Nutrition, that is, the use of nutrition by a medical doctor to diagnose and treat disease. Dr. Rahnama has helped thousands of people achieve their goals of weight loss, gut health, improved mood and sleep, and managing chronic disease. 

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