The Benefits Of Supplementing With L-Tryptophan

August 15, 2017 |


L-tryptophan is an amino acid needed to synthesize proteins. It is also required to produce serotonin and melatonin. In the brain, l-tryptophan converts into serotonin where it promotes feelings of relaxation and comfort to help boost your mood and make it easier for you to fall asleep.

Your body’s l-tryptophan levels naturally decrease with age. Human studies show that low concentrations of l-tryptophan are linked to insomnia. Taking l-tryptophan in supplement form may help get your sleep cycle back on track. Low tryptophan levels have also been associated with depression, weight gain, and carbohydrate cravings (1).

Here’s everything you need to know about taking l-tryptophan as a supplement!

Quick Facts About L-Tryptophan

  • L-tryptophan is an amino acid needed to make serotonin in the body. Serotonin is a neurotransmitter that promotes restorative sleep, happiness, and general feelings of well-being. People often become depressed, anxious or have problems sleeping when their serotonin levels are low. They also tend to experience an increased urge to overeat.
  • Although some foods contain l-tryptophan, your diet alone does not produce enough tryptophan to provide you with proper amounts of serotonin. Enzymes in the body that are needed to convert tryptophan to serotonin may break down due to inflammation and other factors before the conversion takes place. Because of this, supplementation might be necessary.
  • People with serotonin deficiency can control their appetite, restore their sleep and enhance their mood through tryptophan supplementation. It is considered safe and side effects are rarely reported, even at higher doses.

How Does L-Tryptophan Work?

L-tryptophan is a precursor for serotonin, melatonin, and the B vitamin niacin. Serotonin is a neurotransmitter with many behavioral functions. It controls your eating habits, sleep, anxiety, mood, appetite, and the regulation of the endocrine system. You can’t supplement with serotonin itself, so taking l-tryptophan is the next best thing. Adult males require 250 mg of tryptophan a day just to maintain their nitrogen balance (1).

Once ingested, l-tryptophan does one of three things (1):

  1. It becomes incorporated into body tissue proteins.
  2. It is converted into serotonin and melatonin.
  3. It is converted into other substances, such as niacin, carbon dioxide, and water.

Tryptophan requires certain enzymes in the body to turn it into other substances. The two primary enzymes that convert l-tryptophan are called indoleamine 2,3-dioxygenase (IDO) and l-tryptophan 2,3-dioxygenase (TDO) (1). When excess levels of l-tryptophan are present, the liver enzyme TDO takes the extra amount of tryptophan and turns it into water, carbon dioxide and ATP. IDO can degrade l-tryptophan even when levels are low.

Once these enzymes get ahold of tryptophan, it is no longer able to be converted into serotonin or turned into protein. Tryptophan can cross the blood-brain barrier where it has profound effects on your brain chemistry. L-tryptophan is one of many amino acids that desire to cross the blood-brain barrier, but there is competition for entry into the brain (1).

Recent research shows that dietary carbohydrates enhance serotonin levels. This is because carbohydrates promote the release of insulin, which is needed to speed up the removal process of other substances that compete with serotonin for entry into the brain. On the other hand, eating a high amount of dietary protein has been shown to make it harder for serotonin to enter the brain by allowing competing amino acids to enter instead (1).

Health Benefits of L-Tryptophan

Most people have heard of taking l-tryptophan to help you sleep, but did you know it can also help boost your workout? Supplementing with l-tryptophan has been shown to improve exercise performance, endurance, and strength (2). One study found that taking l-tryptophan can help you increase your workouts by 49 percent due to the way it makes you perceive your levels of fatigue. Another study found that distance runners who supplemented with l-tryptophan increased their workout by more than a half a kilometer (2). In other words, l-tryptophan can help you work out longer with less pain (2).

L-tryptophan has also been shown to :

  • Increase sleep quality
  • Enhance your mood
  • Decrease aggression, anxiety, and depression
  • Assist with addiction recovery
  • Prevent and reduce migraines and headaches
  • Reduce carbohydrate cravings and help to avoid overeating
  • Help you maintain a healthy weight
  • Reduce stress

How To Take L-Tryptophan

Take tryptophan as directed by the instructions on your supplement label. Most supplement forms are available as a pill or capsule that can be taken with water. When using tryptophan to help you fall asleep at night, try taking it 30 minutes to two hours before bed. Do not drink alcohol, smoke, or consume drugs while taking tryptophan.

How Much L-Tryptophan Should You Take?

There is no daily recommended intake of l-tryptophan. The best way to determine the correct amount for you is to experiment with various doses. Unlike many other sedative medications, l-tryptophan does not have opioid-like effects and administration does not limit cognitive performance (1), so it’s considered safe to experiment with. 

Research shows that l-tryptophan supplementation in the form of 1000 mg can help regulate sleep cycles. Other research has shown that taking amounts as low as 250 mg can improve stage four of sleep or deep sleep. For sleep apnea patients, taking 2,500 mg of l-tryptophan at bedtime has been shown to improve symptoms in the most severe cases (1).

Research shows that people who take l-tryptophan at night are more likely to wake up feeling refreshed with increased alertness. They also tend to have clearer thought patterns and perform better on tasks that require their attention (2).

One study found that older adults who ate a breakfast cereal twice a day with 60 milligrams of tryptophan per ounce saw improvements in the time it took them to fall asleep. They also experienced increased sleep time and were less likely to wake up in the middle of the night. A ten ounce serving of the cereal provides 600 mg of tryptophan (2).

Another study found that taking 2.5 grams of tryptophan at night improved baseline sleep patterns in patients with obstructive sleep apnea (2). The study determined that patients also increased the amount of time they spent in REM sleep and reduced the time it took to get there. Decreased REM sleep is linked to problems with alertness, fatigue, and even narcolepsy-like symptoms the next day (2).

Patients who described themselves as “quarrelsome” saw improvements from taking 1,000 mg of l-tryptophan three times a day. Results showed that subjects had significant increases in agreeable behavior and decreased their levels of quarrelsomeness (2). Another study found that ten-year-old boys with physical aggression tendencies benefited from a single dose of 500 mg of l-tryptophan. Results showed that the boys who took the tryptophan adjusted their behavior to help other kids become less aggressive. It also helped them become less aggressive when provoked (2).

The best way to find the amount that works for you is to pay attention to how you feel. If you wake up after a full night of sleep feeling refreshed, your dose is just right. If you are still experiencing trouble falling asleep at night, try gradually increasing your amount. Be sure any changes you make are gradual to give your body time to adjust.


Does L-Tryptophan Lose Its Effectiveness Over Time?

Research shows that l-tryptophan does not cause tolerance or difficulty waking in the morning (1). It has also been shown to be useful in the treatment of sleep disorders at various doses without losing its effectiveness over time.

A good rule of thumb is to regulate the doses you take or cycle your l-tryptophan intake. For example, if you take l-tryptophan every night and find that it might not be working as well as it once did, skip a day or two and then resume. 

Can I Take L-Tryptophan With Melatonin?

Melatonin and l-tryptophan work together in the body to naturally help you sleep and feel relaxed, which is why many health products contain both ingredients. Using both ingredients at the same time is safe when taken responsibly. L-tryptophan can help boost your mood by reducing depression and anxiety (2) while melatonin can help make you feel sleepy (3).

Does L-Tryptophan React With Any Prescription Drugs?

Avoid taking l-tryptophan with tobacco, nicotine and alcohol products. According to a report conducted by, you should not take tryptophan if you are currently on one of the following drugs (4):

  • Methylene Blue
  • Iproniazid
  • Furazolidone
  • Tranylcypromine
  • Linezolid
  • Isocarboxazid
  • Phenelzine
  • Moclobemide
  • Procarbazine
  • Selegiline
  • Rasagiline

Consult your doctor before taking l-tryptophan if you are currently taking one of the following medications (4):

  • Alfentanil
  • Amitriptyline
  • Morphine
  • Amphetamine
  • Desvenlafaxine
  • Buprenorphine
  • Butorphanol
  • Citalopram
  • Clorgyline
  • Codeine
  • Dextroamphetamine
  • Dihydrocodeine
  • Dolasetron
  • Duloxetine
  • Remifentanil
  • Almotriptan
  • Fentanyl
  • Fluoxetine
  • Frovatriptan
  • Granisetron
  • Hydrocodone
  • Amoxapine
  • Hydromorphone
  • Hydroxytryptophan
  • Escitalopram
  • Imipramine
  • Levorphanol
  • Tapentadol
  • Lithium
  • Lorcaserin
  • Vilazodone
  • Methadone
  • Methamphetamine
  • Milnacipran
  • Mirtazapine
  • Morphine Sulfate Liposome
  • Nalbuphine
  • Naratriptan
  • Oxycodone
  • Benzphetamine
  • Oxymorphone
  • Palonosetron
  • Paroxetine
  • Pentazocine
  • Lisdexamfetamine
  • Sertraline
  • Sibutramine
  • Sufentanil
  • Meperidine
  • Tramadol
  • Trazodone
  • Fluvoxamine
  • Ziprasidone

Side Effects of L-Tryptophan

L-tryptophan has been shown to be safe and efficient, but everyone reacts differently to supplements. The following is a list of rare but possible side effects:

  • Confusion or agitation
  • Diarrhea
  • Fever
  • Poor coordination
  • Overactive reflexes
  • Shivering or sweating
  • Shaking or trembling
  • Twitching
  • Vomiting
  • Restlessness

Some side effects may go away on their own and do not need medical treatment. These may include:

  • Drowsiness
  • Dizziness
  • Headache
  • Dry mouth
  • Nausea
  • Loss of appetite

Who Shouldn’t Take L-Tryptophan?

Although l-tryptophan has been proven to be relatively safe, non-toxic, and not addictive, people with the following conditions should avoid taking it (4):

  • L-tryptophan may cause breathing problems in patients with digestive problems such as malabsorption and achlorhydria
  • L-tryptophan may increase the risk of bladder cancer and cataracts
  • L-tryptophan may contribute to diabetes in people who have a family history
  • Pregnant or breastfeeding women

Is L-Tryptophan Safe for Children?

L-tryptophan is considered safe enough to be used by children. According to one study, the brains of children with ADHD have protein deficiency. Specifically, the study found that the connective tissue cells of brains in boys with ADHD were not able to convert tryptophan as well as kids without ADHD. Because of this, supplementing with tryptophan may help improve ADHD symptoms in children with hyper attention deficit disorders (5).

L-tryptophan is also a proven mood enhancer and has shown to reduce aggression, which may help assist children with learning or behavioral disorders. Finally, l-tryptophan has been demonstrated to be a safe and effective sleep enhancer. Sleep is of particular importance for the proper development of children's brains. Supplementing with lower doses of tryptophan may help children as well as adults.