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Even 20 % of the people report depression and almost all experienced extended periods of feeling blue. A low mood might be linked to your brain serotonin levels. Serotonin is a signaling hormone produced in the brain and gut and it is linked to a happy mood and contentment. Low levels of serotonin are linked to feeling sad, depressed, anxious, irritated, anti-social, and even hostile. Depression, for instance, is often treated with medications affecting the serotonergic system. Correcting serotonin levels are linked to better mood, motivation, sociability, contentment, and agreeableness. Serotonin receptors are also found in brain areas important for learning and memory, such as the amygdala and hippocampus. In addition, serotonin production is fundamentally important for sleep, as serotonin is the precursor of the sleep hormone melatonin. Serotonin is also involved with many everyday behaviors, for example, eating. Thus, imbalances in the serotonergic signaling can also be related to excessive eating, obesity, and insomnia.

Being cheerless for long periods of time can be fatiguing and distressing. Studies show that positive emotions and sense of purpose are associated with improved immunity, work productivity, better social relationships, and even a longer lifespan. If you feel blue, but not clinically depressed, you can try these natural ways to increase your serotonin levels (though some of these tools have also been noticed to ease clinical depression).

Hox. This article is not for treating clinical depression or replacing any medication. Always consult your doctor if you consider a new supplement.


How to increase brain serotonin naturally?

1. Bright light, sunlight, and serotonin

Do you feel more energetic and happy in the summertime? Sunlight is associated with serotonin levels and it’s been noticed that serotonin turnover is higher during summer than winter. Also, indirect evidence seems to suggest that bright light can uplift mood also when there is plenty of natural light. In studies, where serotonin levels are manipulated by a procedure called Acute Tryptophan Depletion (ATD) participants typically experience a dip in mood. However, carrying the study in bright light (>3000 lux), prevents the mood-lowering effect. Thus, it is advisable to take enough breaks from indoor work, get some sun, and elevate that serotonin! This is an investment in your mood and motivation and can also increase work productivity. Another way to ensure daily sunlight exposure is to go for a short walk first thing in the morning or do some morning stretching in the backyard. Getting sunlight in the morning has an extra benefit of aligning your circadian rhythm and supporting evening melatonin production (and thus, sleep).

If you happen to live in the Nordics (like myself) and the sunlight is scarce during the winter, a Seasonal Affective Disorder light (SAD light) is an excellent option for bright light exposure. SAD lights mimic sunlight as long as it is a minimum of 10 000 lux. I have used SAD lights for years and I could not imagine another winter without it. Bright light treatments are also used for seasonal depression, aka, the winter blues.

Take homes:

  • Sunlight is linked to brain serotonin and mood
  • Take enough breaks in the sun during the day
  • Getting sunlight exposure for 15 minutes in the morning also aligns circadian rhythm and supports sleep


2. Exercise

Exercise has a well-established antidepressant effect. It is even recommended as a supplemental treatment for depression because it can improve mood both in subclinical populations as well as clinically depressed patients. The ‘negative’ side effects of exercise,  such as muscle strain, are outweighed by the positive effects of weight loss, detox, muscle gain, better sleep, better memory, and a better mood. Several studies suggest that exercise also increases the brain’s serotonin. Movement can potentially increase the activity of serotonergic brain cells which results in increased serotonin production. Additionally, exercise increases levels of tryptophan (an amino acid used in making serotonin). At the same time, exercise leads to depletion in plasma levels of branched-chain amino acids (BCAAs). Since BCAAs prevent the tryptophan from traveling to the brain, depletion of BCAAs aids the brain to receive more tryptophan and improves its ability to build serotonin.


Take homes: 

  • Exercise can improve the brain’s ability to receive more tryptophan and thus support serotonin production
  • Exercise can also improve mood in clinically depressed populations


3. Tryptophan and L-tryptophan

One of the most important building blocks for serotonin is the amino acid tryptophan. Amino acids are building blocks of proteins. Some foods naturally contain tryptophan and it’s also sold in supplement form in higher doses (e.g., 200-1000mg). Supplemental tryptophan can increase brain serotonin. Tryptophan supplementation has shown to increase positive emotions, contentment, and agreeable social behavior. Acute Tryptophan Depletion (an experimental condition in which 5-HT levels are acutely depleted) leads to higher aggression and quarrelsome behavior. Tryptophan supplementation has shown to change behavior and feelings to more agreeable (and less quarrelsome) in daily social situations. Because we mirror each other’s emotions and feelings, it can lead to receiving more positive social responses. These daily positive feedback loops with other people can further increase the frequency of shared positive moments in life. Tryptophan supplementation has even been effective in decreasing depressive symptoms in patients with mild-to-moderate depression.

In addition, tryptophan has shown to facilitate sleep and morning alertness. This is probably due to the fact that serotonin and melatonin synthesis requires sufficient levels of tryptophan. 


Take homes:

  • There is some evidence that tryptophan supplement increase contentment and agreeable social behavior
  • Tryptophan supplement can support sleep and morning alertness


4. Nutrients that facilitate serotonin synthesis

Some nutrients facilitate the synthesis of serotonin in the brain and gut. Making sure that the diet provides sufficient amounts of these vitamins may aid serotonin production. These include vitamin C, zinc, vitamin B6, magnesium, and folate.


Food sources for serotonin precursors:

  • Vitamin C: guava, red peppers, kiwi, orange, broccoli 
  • Vitamin B: fish, eggs, nutritional yeast
  • Folate: liver, kidney, basil, nettle, parsley, beetroot
  • Zinc: oysters, red meat, cashews, almonds


5. Positive psychology interventions

It has been acknowledged that the link between serotonin and mood could be a 2-way road. This means that not only increased serotonin leads to better mood, but also positive mood can increase serotonin synthesis in the brain. For example, when people are asked to recall a positive life event, the serotonin synthesis increases compared to recalling sad or neutral emotional events. 


A scientifically studied practice for positive emotions: 3 good things exercise


  • Take your journal and write down three things that went well today and why
  • The event can be big or small, anything from a nice nature walk to a promotion, as long as it makes you feel contentment and joy
  • Give the event a title and include some detail in the description. Try to recall the emotion from that moment.
  • Practice this whenever you feel distressed, worried, or just want to increase your positive emotions. This also helps you to recognize and seek more positive moments in the future and make you more likely to approach situations that give you joy

Other positive psychology interventions

  • Loving-Kindness (metta) meditation 
  • Gratitude journaling
  • Gratitude letter
  • Expressive wiring
  • Imagining a positive future


Do turkey and bananas increase brain serotonin?


A popular belief is that eating tryptophan-rich foods such as turkey or cheese, increase brain serotonin. Though a balanced and healthy diet definitely plays a big role in brain functions, there is no support for the claim that protein-rich foods, in general ,increase brain serotonin levels. This is because tryptophan transportation to the brain competes with the transport of all neutral amino acids in the food. The relatively low rise in plasma tryptophan compared to the big rise in the levels of larger neutral amino acids is too low for increasing brain tryptophan. However, some studies support the idea that increasing dietary tryptophan relative to dietary intake of other amino acids could possibly improve mental health. However, this theory is not systematically studied.

A systematic review from 2007 also debunks another popular myth for increasing brain serotonin with bananas. Even though bananas contain phytoserotonin (plant-based serotonin), serotonin does not cross the blood-brain-barrier (which surrounds the brain), therefore, banana’s serotonin will not travel to the brain. However, serotonin is also fundamentally important for gut health and gut microbiota. Gut microbiota, in turn, has an effect on the production of brain neurotransmitters, including serotonin. The mood-enhancing effect of bananas could also be explained by improved gut mobility or the potassium and vitamin B6 content in bananas which can boost energy levels. Banana also decreases hunger.

Yet, a healthy and balanced diet plays a significant role in the production and synthesis of neurotransmitters, gut health, and nervous system balance. There is also a clear link between diet and mood. Thus, a healthy and balanced diet is advised if the aim is to improve mood.

Take homes:

  • In protein-rich foods, the tryptophan content is too low to increase brain tryptophan
  • Banana contains phytoserotonin, which can not travel to the brain
  • Diet is, however, fundamentally important for gut health, which mediates neurotransmitter production, mood, and overall wellbeing



  • Serotonin is a hormone in the brain (neurotransmitter) and gut
  • It is linked to mood, motivation, sociability, contentment, and agreeableness
  • Low levels of serotonin is linked to feeling sad, irritated, anti-social, and hostile
  • Serotonin turnover is higher when more sun is available. Sunlight is linked to serotonin. 
  • Exercise can potentially increase the activity of serotonergic brain cells which results in increased serotonin production. Additionally, exercise increases levels of tryptophan (an amino acid used in making serotonin).
  • Tryptophan is an important building block of serotonin. Tryptophan supplementation has shown to increase positive emotions and tryptophan depletion lead to higher aggression and quarrelsome behaviour.
  • There is no evidence that bananas and turkey would increase brain serotonin, however, a balanced diet and healthy gut can improve serotonin synthesis and mood
  • Serotonin and mood is a 2-way road. Positive psychology interventions might increase serotonin synthesis