If you haven’t checked out our blogs on tryptophan for anxiety, why tryptophan makes you sleepy and is L-tryptophan safe? You should definitely do that because there’s a lot of great information to know about tryptophan.

But if you’re looking for the Reader’s Digest version that can help you decide whether you want to invest in tryptophan or 5-HTP, you’ve come to the right place.

Let’s dive in.

What is Tryptophan?

Tryptophan is an essential amino acid that can be used to synthesize proteins (because remember amino acids are used to create proteins), but also to synthesize other vital compounds like melatonin, 5-HT (serotonin), kynurenin (KYN), indole-3-acetic acid (IAA), and the vitamin niacin (B3) [1].

It’s been shown to be useful for treating a multitude of conditions, including anxiety, insomnia, and depression, along with having an important role in mood, behaviour, and cognition [2].

What about 5-HTP—what’s that all about?

5-HTP, more scientifically known as 5-hydroxytryptophan, is a naturally occurring compound in the body that is produced during the metabolization of tryptophan.

Similar to tryptophan, 5-HTP is commonly used for:

  • Sleep disorders
  • Anxiety
  • Fibromyalgia
  • PMS and menopause symptoms
  • Headaches

If you’ve ever looked at mood or sleep supplements before, you’ve probably seen 5-HTP on just about every one of them. Want to know why?

As a chemical by-product of L-tryptophan, 5-HTP is also the immediate precursor to serotonin, which is then used to synthesize melatonin.

When the body metabolizes tryptophan, this is what happens:

L-tryptophan → 5-Hydroxytryptophan (5-HTP) → Serotonin → N-acetylserotonin → Melatonin

As you can see here, both L-tryptophan and 5-HTP are used in the synthesis pathway of serotonin or melatonin.

So, what’s all this fuss about one being better than the other if they both do the same job?

Here’s what.

They may both synthesize the same compounds, but the efficacy of these pathways is what sets them apart, what makes them each beneficial in their own way, and also what’s going to dictate who wins the battle of being the better man for a specific job.

Here is what you need to know about 5-HTP:

It doesn’t have the same amino acid competition

Remember we talked about the downside of tryptophan during its road trip to become melatonin?

That, for it to get onto the transport proteins that shuttle it into the brain, it has to compete against larger amino acids like valine, leucine, isoleucine, and methionine.

And when concentrations of these amino acids are higher, as is the case when you eat food sources of tryptophan, the amount of tryptophan that crosses the blood-brain barrier is sparse.

If it just sneaks in and snags a spot on a transport protein, only once it’s actually shuttled across the blood-brain barrier can it be converted into serotonin and melatonin.

Well, 5-HTP doesn’t have to do that.

5-HTP can readily cross the blood-brain barrier with no competition from surrounding amino acids, which means it’s more useful for increasing CNS synthesis of serotonin than L-tryptophan [3].

Here’s the thing with the blood-brain barrier and why it can pose a bit of a challenge for some molecules:

To cross the blood-brain barrier, compounds must have the necessary transport mechanism to get them through [4].

But serotonin doesn’t have that, so it cannot permeate into the brain. But lucky for L-tryptophan and 5-HTP, they have these mechanisms and can therefore cross the barrier.

Once again, with tryptophan, we have to consider all the competition that blocks entry into the brain.

Also keep in mind that because serotonin cannot cross the blood-brain barrier, the amount of serotonin produced depends on the concentration of nutrients (amino acid precursors) available to be synthesized into new neurotransmitters [5].

The more tryptophan and 5-HTP that are available, the more serotonin is going to be produced.

It’s freely converted to serotonin

As we’ve said many times, there’s a lot of competition to get tryptophan into the brain, so its conversion to serotonin and melatonin is rather slow. And in this game, it’s not always about slow and steady wins the race.

Absorption of 5-HTP, on the other hand, does not require a transport molecule and is not affected by other amino acids [3].

So, unlike tryptophan, 5-HTP has a bit of an advantage here in that can be taken with food and you don’t have to worry about whether it will be absorbed.

And remember this: as an amino acid, tryptophan has a few different fates. It can become a protein; it can synthesize niacin (B3), or it can take the serotonin pathway. Out of these three pathways, which one is it going to go towards?

It’s anybody’s guess.

But 5-HTP? It need not worry about whether it’s going to be shunted elsewhere because it can’t be used to synthesize proteins or niacin. So what’s left? Only serotonin.

And because of its role in serotonin synthesis, it also makes melatonin

Like tryptophan, 5-HTP is also a precursor to the synthesis of serotonin, which means it has a positive effect on the production of melatonin—the hormone needed for sleep.

But that’s not to say that L-tryptophan doesn’t have the same effect, hence why it’s often used in sleep aids, just like Performance Lab Sleep.

And interestingly enough, combining 5-HTP with GABA may be a supercharged combo.

GABA is the brain’s primary inhibitory neurotransmitter that helps to induce relaxation and calmness by inhibiting nerve transmission in the brain.

Combined, they help to reduce time to fall asleep, decrease sleep latency, increase the duration of sleep, and improve the overall quality of sleep [6].

But be cautious…

One of the lesser-known things about 5-HTP supplementation, and any serotonin precursor, is that when taken on its own, 5-HTP can deplete dopamine, epinephrine, and norepinephrine levels.

Consequently, you increase your risk of developing depression and high-stress levels.

That’s because serotonin synthesis from 5-HTP, and dopamine from L-dopa, is catalyzed by the same enzyme, L-aromatic amino acid decarboxylase (AAAD).

When you don’t take these precursors in balanced amounts, 5-HTP conversion dominates dopamine at the enzyme levels.

This competitive inhibition can lead to a deficiency of dopamine, as well as a lack of the other catecholamines [5]. And when dopamine levels are insufficient, 5-HTP will no longer function.

To avoid falling into this trap, don’t supplement with 5-HTP long-term.

And be advised that short-term use of 5-HTP may cause mild side effects, including heartburn, stomach pain, nausea and vomiting, diarrhea, and drowsiness.

Tryptophan, however, doesn’t appear to have any severe side effects, aside from minimal cases of mild nausea, headaches, and drowsiness [7].

Who’s the winner?

There’s no winner or loser in this situation. Whether you go with L-tryptophan or 5-HTP is going to depend on what you’re looking to get out of it.

5-HTP may synthesize serotonin faster and more effectively than L-tryptophan, making it a great option if you’re looking to boost mood.

But if you’re looking to improve your sleep and overall well-being, consider L-tryptophan.

References

  1. M Friedman. Analysis, Nutrition, and Health Benefits of Tryptophan. Int J Tryptophan Res. 2018; 11.
  2. DM Richard, MA Dawes, CW Mathias, A Acheson, N Hill-Kapturczak, DM Dougherty. L-Tryptophan: Basic Metabolic Functions, Behavioral Research and Therapeutic Indications. Int J Tryptophan Res. 2009; 2: 45-60.
  3. TC Birdsall. 5-Hydroxytryptophan: a clinically-effective serotonin precursor. Altern Med Rev. 1998 Aug; 3(4): 271-80.
  4. CM Bellettato, M Scarpa. Possible strategies to cross the blood–brain barrier. Ital J Pediatr. 2018; 44.
  5. M Hinz, A Stein, T Uncini. 5-HTP efficacy and contraindications. Neuropsychiatr Dis Treat. 2012; 8: 323-328.
  6. W Shell, D Bullias, E Charuvastra, LA May, DS Silver. A randomized, placebo-controlled trial of an amino acid preparation on timing and quality of sleep. Am J Ther. 2010 Mar-Apr; 17(2): 133-139.
  7. JD Fernstrom. Effects and Side Effects Associated with the Non-Nutritional Use of Tryptophan by Humans. The Journal of Nutrition. Dec 2012; 142(12): 2236S–2244S.