Difference Between 5 HTP Tryptophan and L-Tryptophan

The key difference between 5 HTP tryptophan and L-tryptophan is that 5 HTP tryptophan molecule has a hydroxyl group attached to the benzene ring, which is absent in the tryptophan and L-tryptophan molecules, whereas L-tryptophan is the L isomer of tryptophan amino acid. 

Tryptophan is an alpha-amino acid that is important in the biosynthesis of proteins. We can denote this biomolecule as Trp. This molecule contains an alpha-amino functional group, an alpha-carboxylic acid group and a side chain indole, which makes the molecule a nonpolar aromatic amino acid.

CONTENTS

1. Overview and Key Difference
2. What is 5 HTP Tryptophan 
3. What is Tryptophan
4. What is L-Tryptophan
5. Side by Side Comparison – 5 HTP Tryptophan vs L-Tryptophan in Tabular Form
6. Summary

What is 5 HTP?

5 HTP tryptophan or 5-hydroxytryptophan is a naturally occurring amino acid which is useful as a chemical precursor. It is also important as a metabolic intermediate in the biosynthesis of the neurotransmitter serotonin.

5 HTP tryptophan is a substance that is sold over the counter in the USA, Canada and the Netherlands. In the UK, 5 HTP tryptophan is sold as a dietary supplement to be used as an antidepressant, appetite suppressant, and sleep aid. There are many different trade names for this compound, such as Cincofarm, Levothym, Levotonine, Oxyfan, Telesol, Tript-OH, and Triptum. According to most research studies, this substance is more effective than the medicine placebo in treating depression.

However, we can observe some drawbacks of using this drug such as its short half-life (which is less than two hours) that can inherently limit the therapeutic potential of 5 HTP tryptophan. Furthermore, there can be some side effects of this drug, including heartburn, stomach pain, nausea, vomiting, diarrhoea, drowsiness, sexual problems, vivid dreaming, nightmares, and muscle problems. However, according to most research studies, this drug does not cause any noticeable haematological or cardiovascular changes.

Inside our body, 5 HTP tryptophan is formed from the amino acid tryptophan via the action of the enzyme tryptophan hydroxylase. This enzyme is one of the biopterin-dependent aromatic amino acid hydroxylases. This production process is the rate-limiting step in the process of 5-HT synthesis.

When we take this drug orally, the upper intestines of our body can absorb it, but the mode of absorption is not clearly known yet. Presumably, it involves the active transport of the drug via amino acid transporters. However, this drug is adequately absorbed by the oral cavity.

We can find 5 HTP tryptophan in food but only in insignificant quantities. It is a chemical compound that is involved intermediately in the metabolism of tryptophan. Furthermore, the seeds of Griffonia simplicifolia shrub is known to have this substance, and so it is used as a herbal supplement as well.

What is Tryptophan?

Tryptophan is an alpha amino acid that is important in the synthesis of proteins. This molecule contains an alpha amino group, an alpha carboxylic acid group and a side chain indole in its structure. These functional groups make this molecule a nonpolar, aromatic amino acid. For humans, this amino acid is an essential amino acid. In other words, the human body cannot synthesize this amino acid, so we need to take it from the diet.

We can observe that tryptophan amino acid occurs in many food items such as chocolate, oats, dried dates, milk, sesame, chickpeas, peanuts, sunflower seed, pumpkin seed, etc. This amino acid was isolated from the hydrolysis of casein by Fredrick Hopkins in 1901.

What is L-Tryptophan?

L-tryptophan is the L isomer of tryptophan amino acid. It is an essential amino acid that can help our body to make proteins and certain brain-signalling chemical components. Our body can convert L-tryptophan into serotonin, a brain chemical component.

We can observe the occurrence of tryptophan in most protein-based food or dietary supplements. Particularly, this substance occurs in chocolate, oats, dried dates, milk, yoghurt, red meat, egg, fish, chickpeas, almonds, etc.

Consumption of tryptophan is considered to be very useful in treating depression and other related diseases or disorders because this compound is converted into 5 HTP tryptophan in our body that eventually converts into serotonin, a neurotransmitter.

What is the Difference Between 5 HTP Tryptophan and L-Tryptophan?

5 HTP tryptophan or 5-hydroxytryptophan is a naturally occurring amino acid which is useful as a chemical precursor. L-tryptophan is the L isomer of tryptophan amino acid. The key difference between 5 HTP tryptophan and L-tryptophan is that 5 HTP tryptophan molecule has a hydroxyl group attached to the benzene ring, which is absent in the tryptophan and L-tryptophan molecules, whereas L-tryptophan is the L isomer of tryptophan amino acid.

Below is a summary tabulation of the difference between 5 HTP tryptophan and L-tryptophan.

Summary – 5 HTP Tryptophan vs L-Tryptophan

5 HTP tryptophan or 5-hydroxytryptophan is a naturally occurring amino acid which is useful as a chemical precursor. L-tryptophan is the L isomer of tryptophan amino acid. The key difference between 5 HTP tryptophan and L-tryptophan is that 5 HTP tryptophan molecule has a hydroxyl group attached to the benzene ring, which is absent in the tryptophan and L-tryptophan molecules, whereas L-tryptophan is the L isomer of tryptophan amino acid.

Reference:

1. “5-Hydroxytryptophan.” 5-Hydroxytryptophan – an Overview | ScienceDirect Topics, Available here.

Image Courtesy:

1. “5-Hydroxy-L-Tryptophan (5-HTP)” By NEUROtiker – Own work (Public Domain) via Commons Wikimedia
2. “L-Tryptophan – L-Tryptophan” By NEUROtiker – Own work (Public Domain) via Commons Wikimedia