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Dr. Anthony Freire Text was Updated on: 03/09/2023 Next review: 03/03/2024

Serotonin (An Overview)

Nerve cells produce serotonin which is a chemical that plays a number of functions in a human body. Its scientific name is 5-hydroxytryptamine, and it is mostly present in the brain, digestive system and blood platelets. Serotonin is made up of tryptophan which is an essential amino acid. This chemical enters our body through the food we eat, such as cheese, red meat and nuts.

Serotonin is both a neurotransmitter and a hormone. It affects many functions of the body, which may also include psychological functions. Lack of serotonin influences the mood, social behaviour, appetite, digestion and memory. It is also known as a happy chemical as it improves the well being of a person.

Functions of Serotonin

Just like other chemicals and minerals, serotonin is also very important for our body as it can affect your emotions and motor skills. Many studies have found that it plays a key role in the functioning of the gastrointestinal tract and central nervous system. Following is the detail of functions played by serotonin in the body:

  1. Bone Density

    There is a very deep connection between serotonin and bone health. Taking a high level of serotonin or an increase in serotonin in the body can lead to osteoporosis and weakness of bones. This may also happen due to the antidepressants taken such as serotonin reuptake inhibitors which can decrease bone mineral density and increase the risks of fractures.

  2. Digestion and Bowel Movement Function

    The digestion and bowel movement of your body is affected by serotonin. As it is mainly found in your stomach and intestines, so it plays a major role in regulating the bowel movement. It also reduces the appetite of a person.

  3. Clotting of Blood

    Serotonin is very helpful in the formation of blood clots. In case of any kind of tissue damage, serotonin is released by the platelets which narrow the tiny arteries making the wound to heal easily.

  4. Mood Swings

    Better known as body’s “feel-good” chemical, serotonin regulates the mood of a person. The high and low level of serotonin causes happiness, anxiety and depression. A low level can lead to depression, and an increased level can decrease encouragement and excitement.

  5. Nausea

    It is because of serotonin that you feel nauseated. It is helpful in the removal of bad food from the body due to its increased production. As the chemical increases in the blood, it encourages the part of the brain that is responsible for causing nausea.

  6. Sleep Function

    The part of the brain which controls the waking and sleep function of your body is stimulated by serotonin.

Symptoms of Serotonin Deficiency

Serotonin deficiency is a part of the complex body system. People who face serotonin deficiency may face other metabolic or health problems. Some of the common signs of serotonin deficiency include:


The main symptom of serotonin deficiency is that it causes depression. Chronic stress and trauma related to life events reduce serotonin. Serotonin deficiency can be due to depression, and if a person faces depression, it can cause serotonin deficiency.

Sleep Alteration

All the sleeping functions, i.e. the ability to feel sleepy, remaining asleep and waking up are all controlled by serotonin. People who have the deficiency of serotonin may face chronic insomnia and fatigue, unusual sleep patterns and vivid dreams.

Chronic Pain

Low level of serotonin may cause chronic pain as it is also responsible for the way the muscles act. The most common type of chronic pain, fibromyalgia, is due to serotonin deficiency. Taking antidepressants can increase serotonin level, which may give some relief in pain.

Difficulty in Learning and Memory Issue

According to some studies, memory and learning difficulty is linked with serotonin deficiency. Other symptoms of serotonin deficiency, such as depression and sleeping disorder, can make it difficult to concentrate and learn.


Another indication of the low level of serotonin is that the person may face anxiety and trauma. Chronic stress can also occur causing the serotonin to decrease.


Schizophrenia is a behaviour of unusual belief, hallucinations and sudden change in the mood or personality. All these signs indicate that the person is suffering from a low level of serotonin.

Disturbance with the Body’s Internal Clock

The circadian rhythm, which is internal clock of the body is regulated by serotonin. Low level of serotonin can deregulate the internal clock causing sleep issues, loss of appetite and other problems. Irregular sleeping schedule and inconsistent hunger and eating pattern could be a reason of disturbed circadian rhythm.

Appetite Problems

Appetite issues and eating disorder includes overeating or not eating enough is also a sign of serotonin deficiency. Apart from this, depression can also affect appetite caused by the low level of serotonin.


Attention deficiency and attention deficiency hyperactivity cause due to serotonin issue. People suffering from this may have difficulty in concentrating; feel bored or unable to sit at one place. This behaviour is normally observed in children who behave aggressively, have unlimited energy and are hyperactive.


Serotonin can affect concentration, memory and other cognitive functions. There is a possibility that a low level of serotonin can lead to dementia as the people grow old.

Cause of Serotonin Deficiency

Researchers are still unable to diagnose the reason behind serotonin deficiency. Lifestyle and psychological facto plays a major role in the decrease and increase of serotonin levels. However, some of the reasons might include:

  • Alcohol, Caffeine and Smoking Cigarette

    People who drink a lot of alcohol or those people who are chain smokers may face low levels of serotonin.

  • Diabetes and Insulin Resistance

    Diabetic patients and people who have insulin resistance issues in the body are also a victim of serotonin deficiency.

  • Diet Pills and Certain Medications

    When people start taking dietary medicines, the level of serotonin in their body decreases, making it difficult to cope up with their daily activities.

  • Hormonal Imbalance

    A change in the level of hormones such as thyroid, adrenal or estrogen may cause the level of serotonin to decrease.

  • Lack of Exercise & Sunlight

    When a person does not do much physical exercise or when the body is not exposed to sunlight suffer from serotonin deficiency.

  • Poor Diet and Indigestion

    Serotonin plays a major role in maintaining the digestive system of a person. Low levels lead to poor digestion and loss of appetite.

  • Stress and Anger

    People face a drop in the level of serotonin when they are under stress and trauma. This also happens when a person is always angry and tense.

Some of the other causes of serotonin deficiency are:

  • Infections
  • Inflammation
  • High Cortisol level
  • Hypoglycemia
  • Artificial Sweetener


Serotonin deficiency is very difficult to diagnose because till now there is no such test which could tell the amount of serotonin in the brain or body. However, through a blood test, serotonin-producing tumours could be diagnosed. Normally, the doctors treat the patient through symptoms instead of testing serotonin levels in the body. They also go through the medical history and the medicines taken by the patient. The following three factors can be considered to diagnose serotonin deficiency:

  1. Measuring the level of any drugs used by the patient in the body
  2. Check if the patient has any sign of infection
  3. Check if any of the body function is affected by serotonin deficiency

The doctor may recommend tests like blood and urine test, X-ray of chest, computerized tomography or lumbar puncture to rule out other causes.

Treatment of Serotonin Deficiency

Serotonin deficiency is treated according to the severity of the symptom faced by the patient. If there are minor symptoms, the doctor will advise to stop taking medicine affecting the serotonin level. Some of the known ways to increase the functioning of serotonin are:

Serotonin Reuptake Inhibitors

Some of the antidepressant medicines are the serotonin reuptake inhibitors which will help the body to use serotonin more effectively. These serotonin inhibitors do not make serotonin but help the body use the existing chemical efficiently. Some of the common inhibitors are:

  1. Citalopram
  2. Escitalopram
  3. Fluoxetine
  4. Sertraline
  5. Paroxetine

Natural Remedies

All the medicines have side effects. Similarly, serotonin inhibitors also don’t suit everyone. They could have an unpleasant side effect. In this case, people could go for some natural remedies. Some of the natural remedies are:

  1. Changing your Mood. By doing something you like or thinking of something which will make you happy could help change the level of serotonin. According to a study, changing your mood or to be happy intentionally could help in increasing serotonin level in the brain.
  2. Exercise. The production and release of serotonin in the brain can easily be increased by adopting any sort of physical activity. Physical activity also keeps a person active and healthy. It also improves the quality of life. Aerobics, walking, running or swimming are the most effective exercises.
  3. Diet. Tryptophan, Vitamin D, Vitamin B, and Omega-3 fatty acids are the nutrients required to increase serotonin production. People should eat more of those foods which contain these nutrients to improve serotonin level.
  4. Bright Light.: Studies have proved that exposure to bright light has been very helpful in increasing serotonin chemical. It could be taken in any form, i.e. through sunlight or a lightbox. Both are handy.

Foods which should be Taken To Increase Serotonin Level

Tryptophan is an amino acid which makes the mood of a person better, and it could boost the level of serotonin. When foods rich in tryptophan are taken in a high amount, it would give a positive mood resulting in better production of serotonin; To grow the manufacture of serotonin in the physique and the brain, tryptophan is the most important chemical required. Some of the foods which should be taken to make serotonin level better are:

High-Protein Foods

Turkey, eggs and cheese have tryptophan, and when these foods are consumed in a large amount, it will increase the level of tryptophan in the blood. As tryptophan increases, serotonin deficiency also decreases.


Bananas can also change the mood of a person as they contain serotonin. This will only happen if the serotonin in the bananas reaches the brain.

Foods Containing Tryptophan

Being the precursor of serotonin, foods which are rich in tryptophan should be added in your daily diet to avoid serotonin deficiency. Some foods which are rich in tryptophan are talbina, salmon, soya products, eggs, cheese and turkey.

Foods Rich in Serotonin

There are some foods which contain serotonin, but there is no known study that whether this serotonin reaches the brain or not. These foods are walnuts, bananas, hickory nuts, pineapples, kiwis, plums and tomatoes.

Relationship between Serotonin and Depression

Depression is caused due to the imbalance of hormones and neurotransmitters I the body. It is also a reason of low levels of serotonin. However, it is still not known whether a low level of serotonin causes depression or due to depression serotonin level lowers. Problems occur when there, the brain cells are unable to produce enough serotonin or when there is less tryptophan in the body. It not only causes depression but also anxiety, panic and excessive anger.

To overcome depression, many antidepressants are given to the patient. The most known antidepressants are serotonin reuptake inhibitors which are designed to make serotonin level better. These SSRIs include Prozac and Zoloft. SSRIs are also considered to improve the mood of a person.

Side Effects of Serotonin Reuptake Inhibitors (SSRIs)

SSRI can have some side effects which may go after a few weeks of treatment. Some of the side effects the person may experience are:

  • Dizziness
  • Nausea, vomiting and diarrhoea
  • Insomnia
  • Headache
  • Dry mouth
  • Nervousness and restlessness
  • Effect on appetite. Some people may lose their desire for food, while others may start eating more.
  • Taking SSRIs also affects the weight of a person. Some people gain more weight, while others reduce their weight.
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