What is Serotonin? Deficiency, Toxicity, and Source

Serotonin, also known as the happy chemical, is essentially a type of chemical that controls several functions of the body. Serotonin is abundantly found in the brain, bowels, and blood platelets. Typically, serotonin is used to transmit signals between different nerve cells, primarily in the body’s muscles.

Moreover, it contributes to the health and well-being and mood of the individual. Serotonin also helps to regulate the sleep-wake cycle of the body. Some other functions of serotonin include controlling appetite, emotions, cognitive, and autonomic functions.


Often low serotonin levels are linked to depression. Antidepressants are primarily used to alter the serotonin proportion in the body to elevate the mood and bring joy or happiness to the individual.

Today’s article will highlight the purpose of serotonin. Furthermore, we will discuss the deficiency and toxicity symptoms of serotonin.

What is Serotonin?

Serotonin is a neurotransmitter, also known as 5-hydroxytryptamine, in our body that is usually secreted by a biochemical conversion process. This unique process combines a protein component tryptophan with a chemical reactor called tryptophan hydroxylase. (1)

Serotonin is usually produced in the intestines and brain. Additionally, it is also present in the blood platelets. Considering the abundance of serotonin present in the body, it has the potential to influence several body and psychological functions.

What is the purpose of serotonin?

Some of the everyday purposes of serotonin in the body include –

Psychological functions

  • Mood elevation – Serotonin has a powerful effect on the brain. It helps to regulate and elevate the mood of the individual. This is why serotonin is often called a natural “feel-good” chemical. Moreover, it helps to provide a feeling of happiness and overall well-being. (2)
  • Sexual activity – serotonin can influence the frequency and intensity of sexual feelings you have.
  • Sleep regulation – typically, serotonin influences the time and quality of sleep. For example, it will help to regulate when, how much, and how well a person sleeps. Dopamine, melatonin, and serotonin together play a crucial role in improving the quality of sleep.
  • Body functions
  • Blood Clotting – serotonin helps to heal wounds mainly that occur due to tissue damage, such as a cut through its ability to constrict the small arteries on the skin.
  • Bone Density – serotonin plays a crucial role in strengthening the bones in the body. However, it acts as a double-edged sword because excessive serotonin levels in the circulatory system can also lead to osteoporosis. (3)
  • Food digestion – Serotonin aids greatly in normal bowel function. It helps to regulate food appetite. Moreover, it plays a protective role in the gut.

What causes serotonin deficiency?

Serotonin deficiency mainly occurs due to two reasons –

  • Insufficient production of serotonin in the body – this can occur due to several factors such as nutritional and vitamin deficiencies.
  • Inefficient use of serotonin in the body may occur due to a lack of serotonin receptors in the brain or impaired function of the receptors in the brain.

Some of the crucial symptoms of serotonin deficiency may include –

  • Low mood – depression, anxiety, low self-esteem (4)
  • Sadness or aggression
  • Poor memory
  • Craving for sweet or starchy foods
  • Difficulty in sleeping

Treatment for a serotonin deficiency and depression

Depression is one of the most dangerous and well-known symptoms of serotonin deficiency. Therefore, it is crucial to understand how much serotonin level is required to elevate the individual’s mood and treat clinical depression.

Selective serotonin reuptake inhibitors

Some recreational drugs often help to increase serotonin levels. Usually, these include selective serotonin reuptake inhibitors or SSRIs. These drugs are very commonly prescribed as antidepressants worldwide.

SSRIs’ mechanism is that these drugs act on the brain receptors to increase serotonin, thereby reducing the symptoms of moderate to severe depression.  Usually, brain cells communicate with each other by releasing neurotransmitters – chemical messengers. This process is known as reuptake. The SSRIs acts as supplements that slow down the function of serotonin blocking receptors in the brain. (5)

This process blocks the serotonin reuptake process and makes an abundant amount of serotonin available in the circulatory system. The increased serotonin levels help to elevate the mood of the individual and give a sense of euphoria.

Some of the commonly used selective serotonin reuptake inhibitors include –

  • Celexa (citalopram)
  • Prozac (fluoxetine)
  • Zoloft (sertraline)
  • Paxil (paroxetine)
  • Lexapro (escitalopram)
  • Luvox (fluvoxamine)

Serotonin-Norepinephrine Reuptake Inhibitors

Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs) are a group of serotonin-based medications that are primarily used for treating depression. The working mechanism of these drugs is usually similar to the Selective serotonin reuptake inhibitors, which block the reuptake of serotonin in the brain.

However, serotonin-norepinephrine reuptake inhibitors, as the name suggests, also act on regulating norepinephrine, which is another neurotransmitter that affects the mood. (6)

Such drugs that act on both the serotonin and norepinephrine in the brain are often known as “Dual-acting antidepressants.” Some of the most commonly used SNRIs include –

  • Tricyclics (TCAs)
  • Monoamine Oxidase Inhibitors (MAOIs)
  • Cymbalta (duloxetine)
  • Pristiq (desvenlafaxine)
  • Effexor (venlafaxine)
  • Fetzima (levomilnacipran)

Tricyclic antidepressants (TCAs) and monoamine oxidase inhibitors (MAOIs) are the two old antidepressants that are incredibly effective in regulating serotonin levels.

The mechanism of action of TCAs works on the principle of blocking the reabsorption of serotonin and epinephrine in the body that increases the amounts of both the neurotransmitters in the brain.

Some of the commonly used TCAs include –

  • Anafranil (clomipramine)
  • Elavil (amitriptyline)
  • Asendin (amoxapine)
  • Surmontil (trimipramine)
  • Tofranil (imipramine)
  • Vivactil (protriptyline)
  • Norpramin (desipramine)
  • Pamelor (nortriptyline)
  • Sinequan (doxepin)

MAOIs help to block the effects of monoamine oxidase enzyme – a component that breaks down serotonin, epinephrine, and dopamine, thereby, increasing the amounts of these neurotransmitters in the brain. Some of the commonly used MAOIs include –

  • Azilect (rasagiline)
  • Nardil (phenelzine)
  • Parnate (tranylcypromine)
  • Emsam (selegiline)
  • Marplan (isocarboxazid)

What happens in serotonin toxicity?

Serotonin toxicity, also known as serotonin syndrome, occurs when a person takes two or more serotonin-boosting drugs simultaneously. During this time, the serotonin supplements further stimulate the CNS and peripheral serotonin receptors, resulting in more than the usual amount of serotonin required by the body.

Some of the drugs and conditions that may cause serotonin toxicity include –

  • SSRIs with triptans – it is a medication used to treat migraine.
  • Dietary supplements
  • Illegal drug abuse
  • Overuse of prescribed Selective serotonin reuptake inhibitors
  • Excessive use of Monoamine Oxidase Inhibitors
  • Overuse of recreational drugs such as ecstasy and MDMA. These recreational drugs mainly lead to a sudden spike or an immediate release of serotonin, which is more than the usual amount required to carry out normal body functions. Moreover, the use of recreational drugs and prescribed serotonergic drugs like Prozac and Paxil can potentially increase the risk of serotonin syndrome. (7)
  • The presence of carcinoid tumors, which are frequently found in the GI tract, can cause excessive and abnormal serotonin release. Often these carcinoid tumors do not show any symptoms. They are commonly diagnosed during tests or procedures performed for correcting any other conditions of the GI tract.

Usually, the serotonin toxicity symptoms may appear around six to eight hours after taking the drug or supplements. One of the most common symptoms of serotonin syndrome leads to excessive nerve activity. Additionally, serotonin syndrome may also show signs like-

  • Feeling agitated and restless
  • Feeling confused
  • Increased heart rate
  • Increased blood pressure
  • Pupil dilation
  • Diarrhea
  • Frequent headaches
  • Shivering and sweating
  • Loss of muscle coordination and muscle rigidity

Some of the severe symptoms of serotonin syndrome may include –

  • High-grade fever
  • Irregular heartbeat
  • Seizures
  • Unconsciousness

The severe symptoms are often life-threatening in around 2 to 12 percent of the cases.

Treatment of serotonin toxicity

The treatment for serotonin toxicity usually focuses on managing the typical symptoms. Moreover, it also helps to restore the normal serotonin levels in the body. One of the prime steps towards treating serotonin toxicity is to discontinue the prescribed serotonin medication. It is essential to monitor the symptoms after stopping the medication.

Severe serotonin syndrome often requires hospital observation. During this period, some medications may be given to relax the muscles, control the heart rate and blood pressure. Oxygen and intravenous fluids may also be given to regulate the levels of oxygen in the bloodstream. Moreover, to treat fever and dehydration.

How can you naturally increase serotonin levels in the body?

Some of the effective natural ways of normalizing serotonin levels in your body and minimizing the risk of serotonin deficiency or toxicity may include the following:

Food habits

While many foods contain serotonin naturally, it is essential to get an equal supply of nutrients, especially tryptophan, vitamin D, vitamin B6, and omega-3 fatty acids. This is because all of these components help to release the serotonin and maintain a balance in the body. Some of the nutrient-rich food products that help to regulate serotonin include –

  • Fruits like bananas
  • Beans such as chickpeas, kidney, pinto, black beans
  • Eggs and turkey
  • Oily, fatty fish like salmon, tuna, mackerel (8)
  • Nuts and seeds like walnuts, flaxseed
  • Leafy greens like spinach, kale
  • Probiotic or fermented foods like kefir, yogurt, tofu

Sun Light Exposure

Sun exposure is crucial for natural vitamin D and serotonin production. Often people with low levels of serotonin are the ones who don’t go out in the sun regularly. There is a scientific theory that links depression with insufficient exposure to sunlight.

This theory states that people feel depressed during the short and dark days of fall and winter. The researchers termed this condition as a mood disorder called a seasonal affective disorder.

It is essential to spend at least 10 – 15 minutes every day outside in the sun. If you live in a place with little or no sunlight, you may try using light therapy to make sure you’re getting your daily dose of the sun.

Regular Exercise

Regular exercise helps to boost serotonin levels in the body. However, the benefits of regular exercise may not be limited to the body functions only. A simple routine workout can significantly help to manage depression and any other mood disorders.

This is because regular exercise promotes cardiovascular health, improves body strength and endurance. Moreover, it helps to maintain a healthy weight. (9)

The best way is to consult your doctor or nutritionist to get a routine workout plan and specific type of exercises that may help you to maintain your serotonin levels and relieve depression.

At-home Massage

At-home massage therapy is one of the most useful and practical methods of promoting the release of serotonin in the body. Moreover, it helps decrease the stress hormone called cortisol, which is well-known for causing depression and anxiety.

At-home massage therapies doe not usually require a trained professional or therapist. Instead, the individual can perform a mere twenty minutes massage with their partner or family member.

This therapy helps to increase both the serotonin and dopamine levels in the body. Moreover, it relaxes the muscles and elevates the mood of the person.


Daily Supplements

As mentioned above, serotonin deficiency is often linked with nutritional deficiencies. While the overall nutrition can be improved through a proper diet, daily supplements can enhance the body’s serotonin levels. Some of the most commonly used dietary supplements for serotonin maintenance may include –

  • Pure tryptophan (10)
  • Probiotics
  • 5-HTP
  • SAMe which stands for S-adenosyl-L-methionine

Take away message

Serotonin is a first neurotransmitter which is popularly known as the happy hormone. This is because it primarily helps to elevate the individual’s mood and minimize the risk of depression and anxiety.

The brain typically releases serotonin into the circulatory system from where it gets absorbed in the muscle cells and nerve cells to balance psychological and body functions. However, some people may be deficient in serotonin. Such people suffer from depression, aggression, anxiety, weak muscle activity, and reduced body performance. Usually, medications like selective serotonin reuptake inhibitors and serotonin-norepinephrine reuptake inhibitors can be used to treat the deficiency disorder.

Serotonin toxicity occurs when the levels spike above the optimal range in the body. Such conditions may lead to increased neurological and cardiovascular symptoms. Serotonin toxicity is treated by discontinuing the serotonin supplements. Some alternative ways of maintaining serotonin levels in the body include diet control, exercise, massage, and dietary supplements.


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