Tryptophan is an amino acid that can be taken as a supplement to boost your mood and your emotional stability, as well as improve your cognitive performance.
Since tryptophan is the sole precursor to the essential neurotransmitter serotonin, proper regulation of tryptophan levels plays a critical role in maintaining a stable mood, avoiding depression, aggression, and impulsive behavior, and ensuring high-quality sleep.
Tryptophan might even be able to increase your working memory during challenging cognitive tasks. If this is your goal—or if you want to push past normal and actually augment your mental well-being and cognitive performance—we’ve ranked the ten highest-quality tryptophan supplements on the market.
1. Amazing Formulas L-Tryptophan
The tryptophan supplement from Amazing Formulas delivers a high dose of tryptophan in a minimal package.
The gelatin capsules contain 1000 mg of tryptophan, along with a bit of magnesium stearate for stability and nothing else. This makes for a strong and reliable source of tryptophan for anyone looking for cognitive enhancement.
2. NOW L-Tryptophan
NOW Foods is known for simple and straightforward supplements, and that’s what they deliver with this tryptophan supplement.
Each capsule has 500 mg of tryptophan, with no additional ingredients aside from stearic acid. Vegetarians and vegans will like the cellulose-based capsule, and everyone can get on board with the moderate dosage and clean supplement design.
3. Superior Labs L-Tryptophan
Superior Labs focuses on delivering a moderate dose of tryptophan with no additives and a high level of purity. The capsules are cellulose-based, have 500 mg of tryptophan each, and come in a fairly ample amount per bottle (120 caps, to be specific).
Though Superior Labs is a smaller brand, this supplement still has a wide base of support among tryptophan supplement users.
4. Pure Naturals L-Tryptophan Pure
Pure Naturals has a moderate dose, high-quality, and American-made tryptophan supplement that’s a good fit for anyone who doesn’t need a high dosage.
The gelatin-based capsules deliver 500 mg of tryptophan, which is plenty for a lot of users. Without anything in the way of unnecessary ingredients, it’s a very solid pick.
5. Longlifenutri L-Tryptophan
Longlifenutri has a pretty basic tryptophan supplement with the standard 500 mg dose per capsule.
The bottle is fairly generous, with 120 capsules included, and the design is clean: the gelatin capsules contain only L-tryptophan and magnesium stearate. Without much to complain about, this is a good solid pick.
6. Jarrow Formulas L-Tryptophan Peptide
Jarrow Formulas is a pretty reliable manufacturer when it comes to pushing out the boundaries on supplements. Unlike the rest of the competition, Jarrow Formulas has their own partially metabolized form of tryptophan that they claim is more effective than free L-tryptophan.
The blend delivers only 250 mg of tryptophan per capsule, but it’s in the form of a tryptophan peptide. Whether you think this is a more effective way to deliver tryptophan depends on the degree to which you believe in the nutritionists at Jarrow Formulas—there’s no published research demonstrating the superiority of the peptide form of tryptophan.
7. BRI Nutrition L-Tryptophan Extra Strength
BRI Nutrition has a fairly standard tryptophan supplement. Don’t let the name fool you; the 500 mg is very much middle of the road.
The ingredients list is pretty clean, with the capsules being derived from cellulose and the only filler being rice flour. While it doesn’t really stand out from the crowd, it’s still a reliable pick.
8. Nutricost L-Tryptophan
Nutricost has a tryptophan supplement that aims to boost absorption and bioavailability by using the proprietary black pepper extract BioPerine.
The supplement includes 5 mg of BioPerine along with 500 mg of tryptophan per capsule. The supplement design could be a little cleaner; there are ingredients like silicon dioxide that some people won’t like.
While it’s unclear whether the BioPerine will make a real difference in tryptophan absorption, it may be worth a try if other supplements aren’t doing the trick, even at a high dose.
9. Source Naturals L-Tryptophan
Though this supplement advertises itself as containing 1.5 grams of tryptophan per serving, it’s a bit misleading: it’s really just 500 mg per capsule, with three capsules recommended as a “serving.”
This by itself isn’t a dealbreaker, but it’s disappointing to see a number of extra ingredients, like dibasic calcium phosphate and silica, that probably don’t need to be in the supplement. It’s not necessarily a bad choice, but Source Naturals L-Tryptophan gets outclassed by the competitions on a number of fronts.
10. Doctor’s Best L-Tryptophan Tryptopure
Doctor’s Best has a tryptophan supplement that uses a proprietary tryptophan preparation, called Tryptopure, to deliver its 500 mg dose.
This is fine, but the real issue with this supplement is that it’s bloated with excessive additives that don’t really improve the quality of the supplement.
While it’s still likely to function just fine, given the choice, it’d probably be better to go with something that’s designed a bit more minimal if ingredients are important to you.
Tryptophan benefits and side effects
Tryptophan plays a core role in regulating your body’s mood and cognitive function.
It’s the primary precursor to the neurotransmitter serotonin (and the only amino acid that can be transformed into serotonin), so modulations in tryptophan levels affect your body’s ability to synthesize and use serotonin.
Given that healthy serotonin levels are critically important for proper cognitive function, it should be no surprise that tryptophan is so intensely studied for its ability to regulate mood and cognitive function.
Low levels of tryptophan are associated with depression symptoms. Depression can manifest as a decrease in levels of the neurotransmitter serotonin; indeed, the most popular category of antidepressant medication is selective serotonin reuptake inhibitors.
These drugs slow the rate at which serotonin is reabsorbed into the brain. When considering the biochemistry of tryptophan, one naturally wonders whether a “supply-side” approach would work too.
This was exactly the question explored by researchers at McGill University in Canada (1). A team of researchers published a study in the journal Psychopharmacology that involved a period of intentional tryptophan depletion, followed by a battery of cognitive and emotional screenings.
Compared to subjects who had not been acutely depleted of tryptophan, the tryptophan-depleted subjects scored higher on a depression inventory and were more easily distracted by negative thoughts during a proofreading task.
Maintaining high tryptophan may be important for staying healthy after recovery from depression. Later research published in The Lancet found a starkly similar effect when women with a history of depression consumed a mixture of amino acids that did not include tryptophan.
Women who had a history of depression, but were currently healthy, experienced a rapid relapse of symptoms when they were acutely depleted of tryptophan (2).
The downward spiral in emotional status was so rapid and so sudden that it’s hard to come up with any other explanation than that serotonin levels crashed after the body’s tryptophan levels were depleted.
A tryptophan supplement might play a role in maintaining good mental health, instead of just being useful as a treatment for depression.
Tryptophan could be used to directly treat depression. Because of the above evidence, among other indicators, tryptophan has been investigated as a direct treatment for depression.
One clinical trial on tryptophan for treating depression was published in the journal Psychological Medicine (3). The study compared a placebo, a traditional antidepressant, and tryptophan for treating depression in a 12-week study.
The results showed that the tryptophan supplement performed as well as the traditional antidepressant, and both performed better than the placebo.
Tryptophan can improve mood, memory, and sleep. Given the wide-ranging effects of serotonin, it should not be particularly surprising that tryptophan has applications that range beyond just treating depression or preventing its recurrence.
A scientific review article by B.Y. Silber and J.A.J. Schmidt published in the scientific journal Neuroscience & BIibehavioral Reviews in 2010 took a closer look at some of the experimental evidence for tryptophan beyond just treating depression (4).
Tryptophan appears to be a strong mood stabilizer, which should not be shocking given the evidence on depression reviewed earlier. These mood improvements aren’t limited to making depressed people feel normal—tryptophan has been used to lower aggression and decrease impulsive behavior associated with ADHD.
But beyond this, tryptophan supplementation appears to reliably improve memory and even improve sleep quality. Improvements in sleep quality shouldn’t be surprising, because tryptophan is chemically related to the sleep-inducing hormone melatonin. The benefits are not universal, though; tryptophan appears to slightly slow your reaction time, perhaps because it works as a mild sedative (hence the sleep quality enhancements).
This suggests that tryptophan supplementation might work best best for slower-paced cognitive tasks that require strong memory skills, like working with information from many different sources at once.
For nootropic use, it’d be best for studying for an exam (a lower pressure task that isn’t time-dependent), not actually taking an exam (which requires rapid-fire cognitive processing ability).
It’s hard to look into tryptophan without running up against one of the biggest stories about devastating side effects in recent memory.
In the late 1980s, an outbreak of a rare and sometimes fatal neurological disease was traced to contaminated samples of tryptophan used in supplements.
The supplements were undeniably linked to the development of the disease, but there still exists controversy over what exactly caused the side effects: researchers disagree whether trace impurities were the sole cause, or if the tryptophan itself played any role (5).
This led to an embargo on tryptophan supplements, which was eventually lifted in 2001, but certain countries are still restricted from importing tryptophan for supplemental use into the United States.
Some researchers, such as D.M. Richard and colleagues at the University of Texas Health Science Center, argue that tryptophan is safe when used at clinical doses, pointing to a large body of clinical literature demonstrating the safety and efficacy of this supplement (6).
Tryptophan should not be used without medical supervision by anyone who is already taking antidepressants, because the combined action of tryptophan and a SSRI or other serotonin-modulating prescription medication can cause serious side effects.
Talk to your doctor first if you already use an antidepressant or other prescription medication that acts on neurotransmitters.
Though tryptophan has been widely studied, there is no general consensus on the optimal dosage. Studies on its use have successfully employed doses from less than one gram per day all the way up to nine grams per day.
The typical dose, and a good starting place, appears to be right around one gram per day, possibly split into two equal doses. From here, you may need to adjust your dosage up or down depending on how your body responds.
Tryptophan, seemingly a simple amino acid, plays a critical role in regulating your cognitive function and well-being because it is a direct precursor to the neurotransmitter serotonin.
Deficits in tryptophan reliably induce symptoms of depression, and can cause recurrence of depression in people who’ve already recovered from it. It’s been researched as a direct treatment for depression and as a way to decrease feelings of aggression and impulsive behavior.
Tryptophan may even boost your memory. For nootropic use, tryptophan seems to work best in situations where you need extended memory capabilities and a stable, relaxed mindset, but don’t need rapid cognitive processing abilities. For those situations, something like caffeine would be better.
To avoid side effects, you should make sure your tryptophan supplement comes from a high-quality manufacturer, and you should not take it without talking to your doctor if you are already taking a prescription medication that acts on serotonin, like an SSRI for depression.
Though its biological activity is complex, this lowly amino acid holds a lot of promise for helping ensure optimal cognitive function.