7 Scientifically Verified Benefits of L-Tryptophan – Better Cognition, Mood, and Sleep

L-Tryptophan is a dietary supplement for improving mood. However, many people don’t understand the full L-Tryptophan benefits. In this article, we explore the top 7 scientifically verified benefits of L-Tryptophan. Many foods with L-Tryptophan are useful for getting a good dose of this powerful amino acid. However, the best way to experience the top L-Tryptophan benefits is by taking a high-quality dietary supplement. If you want to learn more about the L-Tryptophan structure, or if you’re still wondering “what is L-Tryptophan?” then read through our informative L-Tryptophan product description. Or, read on to learn about the top L-Tryptophan benefits. [caption id=""attachment_2111"" align=""alignright"" width=""690""] Evidence suggests that L-Tryptophan is able to boost mental focus and memory[/caption]

Top L-Tryptophan Sources

Nutrition Data, an offshoot of Self Magazine, has become one of the most authoritative nutrition facts websites since its launch in 2003. Its goal is to provide unbiased, comprehensive nutritional information for the general public. The website lists information that has been sourced from both the USDA's National Nutrient Database for Standard Reference and the manufacture’s information sheets for the products reviewed.[1] Nutrition Data listed the top dietary sources of L-Tryptophan. Their nutrition experts stated that the top sources of L-Tryptophan are: first, sea lion kidney and second, sea lion meat. Since these are not common foods for most people, we’ll omit them from the following list: (Ranked in milligrams of L-Tryptophan per 200 calorie serving):

1. Game meat  (746 mg)
2. Raw spirulina seaweed   (739 mg)
3. Soy protein isolate   (695 mg)
4. Dried, powdered egg white   (673 mg)
5. Low-fat sesame seed flour   (659 mg)
6. Dried spirulina seaweed   (641 mg)
7. Raw crab meat   (607 mg)
8. Soy sauce    (603 mg)
9. Chopped spinach   (594 mg)
10. Cooked Halibut fish with skin   (593 mg) [2]

  While these food sources are all very high in L-Tryptophan, many of them are also high in other amino acids, which may compete with L-Tryptophan for absorption. As we explore later, studies have shown that carbohydrate-rich, low-protein meals are best for improving L-Tryptophan absorption. [caption id=""attachment_2112"" align=""alignright"" width=""690""] Spirulina is a great natural source of L-Tryptophan[/caption] The best way to improve your L-Tryptophan levels is to use a high-quality L-Tryptophan dietary supplement. Scientists have verified the following seven benefits of using L-Tryptophan supplements:  

1.    L-Tryptophan and Cognition

L-Tryptophan has a complex role in cognition. First and foremost, L-Tryptophan is the chemical precursor to serotonin (5-HT). Your body converts L-Tryptophan into serotonin through a multi-step process using enzymes called tryptophan hydroxylase and aromatic L-amino acid decarboxylase. [3] Serotonin’s role in cognitive performance is well studied and is in the process of being fully elucidated through ongoing research. Low serotonin levels are strongly correlated to impaired cognitive performance – especially memory formation. Furthermore, researchers have suggested using serotonin receptors as targets for improving cognition in depression and Alzheimer’s disease. [4] However, the relationship between serotonin, L-Tryptophan, and cognition is not completely understood. Studies have indicated that L-Tryptophan may affect cognition differently in different individuals.   Specifically, a 2003 review found that L-Tryptophan depletion impaired memory but slightly improved attention. Furthermore, the authors of the review found that L-Tryptophan depletion impaired problem-solving abilities in people with a family history of low mood, but improved problem-solving in people with an otherwise healthy family history. [5] In a 2006 clinical study, researchers found that L-Tryptophan supplements induced a positive bias in processing emotional material. In other words, L-Tryptophan improved mood and generated a positive outlook. However, these results were only relevant to the female volunteers who participated in the study – not the men. [6] What we definitely know is that the role of L-Tryptophan in human cognition is complex and requires further research to fully understand its effects. It is, however, understood that L-Tryptophan supplements positively affect memory in humans. [7] [caption id=""attachment_2113"" align=""aligncenter"" width=""692""] Studies have shown that L-Tryptophan helps to improve memory and cognition[/caption]

2.    L-Tryptophan and Mood

In 2016, scientists published an in-depth review about how L-Tryptophan and serotonin affect mood and cognition. The review was published in Nutrients, a distinguished academic journal for nutrition research. According to studies cited by the researchers, L-Tryptophan depletion has a varied effect on mood. In a similar way to how it affects cognition, L-Tryptophan appears to affect people’s moods based on whether or not they have a personal or family history of low mood. It is clear that improved L-Tryptophan levels are consistently associated with a better mood. Also, people with a history of low moods are more susceptible to mood changes based on L-Tryptophan levels. [8]   Another study, published in 2015, on 59 healthy middle-aged women found that daily L-Tryptophan supplements (0.5grams twice daily) ‘improved emotional processing’ and boosted overall mood. The experiment was conducted over 19 days and the results showed improved mental alertness, mood boost, and a feeling of happiness when taken before bed. [9] L-Tryptophan supplements improve sleep patterns. Researchers now believe that this is another reason to support using L-Tryptophan for mood improvements. The effects of sleep on mood are well understood - both the length and quality of sleep are important in maintaining a good mood. [10]

3.    L-Tryptophan for Stress-Relief

In addition to improving mood, many people use L-Tryptophan to reduce feelings of stress. This is often a byproduct of the improved mood and better sleep that result from using L-Tryptophan supplements.   [caption id=""attachment_1297"" align=""alignright"" width=""290""] Liftmode's L-tryptophan, 98+% purity[/caption] Studies have looked into L-Tryptophan’s effects on stress in both humans and animals. The results are encouraging. For example, the first human study available was published in 1985. Researchers looked at the effects of L-Tryptophan supplements on ten participants suffering from various states of stress. The supplements resulted in a significant reduction in stress scores for all patients. [11]   However, the 1985 study used L-Tryptophan in conjunction with a chemical agent used to reduce the activity of dopamine decarboxylase (theoretically strengthening L-Tryptophan’s effects).   Another study, published in 1986, looked into the effects of childbirth on natural L-Tryptophan levels. Women who suffered from post-childbirth ‘blues’ tended to have lower L-Tryptophan levels and higher cortisol levels compared to those who didn’t. [12]   More recently, a study published in 2014 looked into the effects of an L-Tryptophan-rich diet on stress-induced alcohol desire in chronic binge drinkers. The binge drinkers who were given a diet rich in L-Tryptophan had a reduced craving for alcohol compared to those receiving the control diet. The scientists concluded that this was an indication that L-Tryptophan could moderate stress response. [13] Interestingly, the desire for a drink in non-binge drinkers actually increased with the L-Tryptophan-rich diet. Although this did not indicate an increase in stress, it showed that L-Tryptophan may work differently in people with different behavior types.   Finally, scientists now believe that people’s individual responses to L-Tryptophan may be genetically predetermined. For example, a 2015 study found that variations in the 5-HTTLPR genotype resulted in different stress responses to L-Tryptophan supplements. [14] [caption id=""attachment_1674"" align=""alignright"" width=""686""] Studies have found that L-Tryptophan supplements help to improve mood and reduce stress[/caption]

4.    L-Tryptophan for Sleep

This is one of the key benefits of L-Tryptophan and has been very well studied in the past. Scientists have verified that L-Tryptophan improves both the time to fall asleep as well as the quality of sleep. In fact, in 1986, a review of the literature was published on using L-Tryptophan as a therapeutic supplement for insomnia. The authors concluded that L-Tryptophan could be used effectively to induce sleep at a dose of between 1 – 15 grams on the first night. For chronic sleep impairment, a low dose could be used repeatedly to improve sleep quality. Extra benefits include the lack of side-effects and the absence of developing tolerance, even when using L-Tryptophan for longer periods of time. [15]   One of the most important aspects of using L-Tryptophan for sleep is that it is effective at improving melatonin levels. Melatonin is known as the ‘sleep hormone’ and helps to promote sleep. L-Tryptophan is converted into serotonin in your body. Excess serotonin is then converted into melatonin in the pineal gland, in response to dark-light cycles and other factors. [16] Even low doses of L-Tryptophan, such as what we would normally consume in our daily diets, have been reported to improve sleep quality. In a 1979 study, the time to fall asleep was significantly improved with just 1 gram of L-Tryptophan. A dose as low as 250 mg was effective at improving stage IV sleep. [17]   Scientists have even suggested using L-Tryptophan to aid in improving the symptoms of sleep apnea. Just 2.5 grams of L-Tryptophan taken before bed significantly improved sleep respiration in volunteers with obstructive sleep apnea (but not central sleep apnea). The L-Tryptophan supplement also lengthened the REM sleep and reduced REM latency in all volunteers. [18]  

5.    L-Tryptophan and Exercise Performance

A lesser-known benefit of L-Tryptophan is that it has the ability to improve exercise performance. Again, although this has been studied in-depth by scientists over the past few decades, the knowledge of these benefits seem to have missed most people. In 1988, scientists published a study on the effects of L-Tryptophan on exercise in the International Journal of Sports Medicine. Twelve healthy volunteers participated in the study, in which they were required to run on a treadmill until exhaustion. A number of factors were measured. Remarkably, the group receiving L-Tryptophan had a 49.4% longer time to exhaustion than the placebo group. Not only this, but those taking L-Tryptophan had a lower perception of exertion. No physiological measures like maximum heart rate, peak oxygen consumption, or pulse recovery rate were affected by the L-Tryptophan supplement. [19]   [caption id=""attachment_2114"" align=""alignright"" width=""300""] 100grams L-Tryptophan from Liftmode,99+% purity[/caption] A second study, published in 2015 in the International Journal of Neuroscience, found similar results. Twelve healthy athletes performed a 20-minute cycle on a cycle ergometer at 50% of their exercise capacity. Each volunteer did one round with L-Tryptophan and another without, in a double-blind, randomized manner. The results showed that with placebo, the average distance covered in the last 20 minutes was 12’000m, while the average distance with L-Tryptophan was closer to 12’600m – a statistically significant improvement. [20]   The theory underlying L-Tryptophan’s ability to improve exercise performance is that, more often than not, people stop their physical exercise not because of muscle fatigue but because of perceived exertion and a lack of neural drive. It seems that altering the serotonin system with L-Tryptophan positively enhances the neural drive and boosts exercise performance. [21] [caption id=""attachment_1989"" align=""aligncenter"" width=""690""] L-Tryptophan has benefits in helping to promote healthy sleep[/caption]

7.    L-Tryptophan for Metabolism

The role of L-Tryptophan in managing weight is not well understood, and there are a number of studies with conflicting results. However, it does not seem that L-Tryptophan can reduce weight directly. A 1985 study published in the Journal of Obesity Studies was entitled: “L-Tryptophan does not increase weight loss for carbohydrate-craving obese subjects”. The study found that supplementing with L-Tryptophan did not significantly increase weight loss in obese volunteers. However, although the results weren’t statistically significant, there was a slight decrease in total body weight for the eight subjects who complete the study with L-Tryptophan – compared to those who took a placebo. The mean weight loss for those on placebo was 1.1kg over 6 weeks, while those taking an L-Tryptophan supplement lost an average of 2.3kg. [25]   One of the key ways that researchers think that chemicals which target serotonin receptors may lead to weight loss is through blocking the cravings for carbohydrates. Serotonin has a complex role in mediating your appetite, this much is known for sure. For example, eating a meal that is rich in carbohydrates and with relatively low protein levels – a meal that is high in vegetables, starch, and fruit, for example – allows your body to produce the proteins required to transport L-Tryptophan into your brain. This can then be converted into serotonin, which mediates appetite. However, a meal that is high in protein and low in carbohydrates supplies your body with a large number of amino acids which compete with L-Tryptophan. As a result, less L-Tryptophan can be transported into your brain, which then produces less serotonin. [26] Quite clearly, this indicates the important role of L-Tryptophan in mediating appetite through its effects on serotonin.

Conclusion

In conclusion, L-Tryptophan is a great supplement with a number of scientifically-verified health benefits. Most importantly, L-Tryptophan positively affects mood and cognition. These effects are best seen in women and in people with a family history of mood disorders. Research has also indicated that L-Tryptophan positively affects your stress levels and helps to improve sleep quality. L-Tryptophan’s influence on sleep is highly underrated considering the vast amount of research showing its positive sleep-enhancing benefits. Even less well-known is L-Tryptophan’s ability to improve exercise performance through the serotonin system. It enhances neural drive and helps to lengthen exercise stamina. Although L-Tryptophan supplements have not yet been established to have a direct positive effect on weight, their influence on stress, mood, cognition, sleep, and exercise, may indicate the potential for an indirect positive effect on your weight. [caption id=""attachment_2115"" align=""alignright"" width=""690""] L-Tryptophan supplements are a great way to boost your mood and add to a healthy lifestyle[/caption]        

References:

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