Why is serotonin produced

In fact, most of the serotonin in your body is found in your gut, not your brain. Not only do the intestines produce almost all of the body's serotonin supply, but serotonin is required there to promote healthy digestion. Elsewhere in the body, serotonin also helps with sleep, sexual function, bone health, and blood clotting.

Here's a closer look at serotonin's many functions, what happens if you have too little or too much , and a few ways to balance your levels for optimum health. Serotonin is known to be involved in many bodily functions, ranging from regulating mood to digesting food. As it helps regulate your mood, serotonin is often called the body's natural "feel-good" chemical.

Serotonin's influence on mood makes it one of several brain chemicals that are integral to your overall sense of well-being. The neurotransmitter's effect on mood is also why it's often a target of medications that are used to treat depression, anxiety, and other mood disorders. For example, increasing serotonin levels is the purpose of the class of antidepressants known as selective serotonin reuptake inhibitors SSRIs.

Serotonin contributes to normal bowel function and reduces your appetite as you eat to help you know when you're full.

The neurotransmitter also plays a protective role in the gut. For example, if you eat something irritating or toxic, your gut responds by producing more serotonin.

The extra "dose" of the chemical moves the unwanted food along, expelling it from your body more quickly. The response is also why increased levels of serotonin can make you nauseated, and why drugs that target specific serotonin receptors can be used to alleviate nausea and vomiting.

The exact nature of serotonin's role in sleep has been debated by researchers, but it's believed to influence when, how much, and how well you sleep. Serotonin does not regulate these tasks alone; other neurotransmitters like dopamine also play a key role. A hormone called melatonin is also critical to the proper functioning of your sleep cycle. Your body needs serotonin to make melatonin, so not having enough of the neurotransmitter or having too much of it can affect the pattern and quality of your sleep.

Your brain has specific areas that control when you fall asleep, regulate your sleep patterns, and wake you up. The parts of your brain that are responsible for regulating sleep also have serotonin receptors. The serotonin-melatonin relationship might also contribute to sleep disruptions like insomnia that are common in people with depression. When you have any kind of tissue damage, such as a cut, the platelet cells in your blood release serotonin to help heal the wound.

Increased serotonin levels cause the tiny arteries known as arterioles of the circulatory system to narrow. As they get smaller, blood flow slows. This narrowing known as vasoconstriction and slowed blood flow are two important elements of blood clotting—a crucial step in the process of wound healing. Studies have shown that serotonin levels may influence bone density the strength of your bones.

Research suggests that high circulating levels of serotonin in the gut might be associated with lower bone density and conditions like osteoporosis. Research suggests that SSRI medications are associated with decreased bone mineral density. Low bone density puts you at a greater risk for fractures. If you are concerned about how taking an antidepressant could affect your bone density, do not stop taking your medication.

Start by talking to your doctor about other risk factors, such as having a family history of osteoporosis or smoking. In addition to altering your mood, serotonin can also influence the frequency and intensity of the sexual feelings you have.

Certain antidepressants that increase serotonin levels can have an effect on libido , as elevated serotonin levels have been associated with a decrease in sexual desire. Serotonin's influence on libido is also somewhat related to the neurotransmitter's relationship to another chemical in the brain: dopamine.

For example, a study of women with hypoactive sexual desire disorder HSDD indicated that symptoms of the condition were associated with increased serotonin activity and reduced dopamine activity. Depression and other mood disorders that are linked to serotonin are multifactorial, meaning there is more than one reason they occur.

Having low serotonin levels is not, on its own, enough to cause depression. Low levels can, however, contribute to mood, sleep, digestive, and other issues. There's no single cause of low serotonin levels, but it typically occurs for one of two reasons: not having enough serotonin or inefficient use of the serotonin you have.

In the first scenario, you have low levels of serotonin because your body is not producing enough to maintain normal levels. Your body might not be able to produce enough serotonin because of other factors, such as nutritional and vitamin deficiencies. For example, low levels of vitamin B6 and vitamin D have both been linked to decreased levels of serotonin.

Tryptophan, an essential amino acid involved in serotonin production, can only be obtained through diet. The other reason you might have low serotonin is that while your body is making serotonin, it is not using it effectively. This can happen if you don't have enough serotonin receptors in your brain, or if the ones you have don't work well for example, they absorb and break down serotonin too quickly.

Depression is known to be associated with chemical imbalances in the brain. While serotonin's role in depression is more complex than an imbalance, it is believed to play a key role. Increasing how much serotonin is in the brain appears to improve communication between brain cells, which in turn lifts mood and reduces symptoms of depression. This is why prescription antidepressant medications are used to treat clinical depression and other mood disorders.

There are also natural ways to increase serotonin levels. Everything from the food you eat to how much sunlight you get can affect how much serotonin your body has, as well as how effectively it can use it.

SSRIs are the most commonly prescribed antidepressants worldwide. These drugs are used to reduce the symptoms of moderate to severe depression by increasing the amount of serotonin in the brain.

When brain cells send signals to one another, they release neurotransmitters, including serotonin. Before they can send the next signal, the cells must reabsorb and recycle the neurotransmitters they released. This process is called reuptake.

Examples of SSRIs that are commonly prescribed to treat depression and other mood disorders include:. Drugs in this class are not solely classified as SSRIs, but rather, as serotonergic antidepressants. Trintellix vortioxetine is a similar drug. Another group of serotonin-based medications for treating depression is known as serotonin-norepinephrine reuptake inhibitors SNRIs.

These drugs work similarly to SSRIs in that they block the reuptake of serotonin, but they also work on norepinephrine , another neurotransmitter that affects mood. Two older classes of antidepressants also affect serotonin levels: tricyclic antidepressants TCAs and monoamine oxidase inhibitors MAOIs.

TCAs appear to block the reabsorption of serotonin and norepinephrine, which effectively increases the amounts available in the brain. Examples of TCAs include:. MAOIs, on the other hand, block the effects of the monoamine oxidase enzyme, which breaks down serotonin, epinephrine, and dopamine. Preventing these neurotransmitters from being broken down effectively increases the amounts available in the brain.

Examples of MAOIs include:. Many foods naturally contain serotonin, but your body also needs other nutrients, such as tryptophan, vitamin B6, vitamin D, and omega-3 fatty acids, to produce the neurotransmitter.

Foods that are good sources of these key nutrients include:. Eating a high-fiber diet that is rich in fruits and vegetables will help keep your gut bacteria healthy. Regular physical activity especially aerobic exercise has been proven to boost serotonin levels. However, the benefits of regular exercise go beyond your brain. A workout can help people manage depression and other mood disorders by also promoting cardiovascular health, improving strength and endurance, and helping to maintain a healthy weight.

New research at Caltech, published in the April 9 issue of the journal Cell , shows that certain bacteria in the gut are important for the production of peripheral serotonin. To start, we explored the idea that normal gut microbes could influence levels of neurotransmitters in their hosts.

Peripheral serotonin is produced in the digestive tract by enterochromaffin EC cells and also by particular types of immune cells and neurons. Hsiao and her colleagues first wanted to know if gut microbes have any effect on serotonin production in the gut and, if so, in which types of cells. They began by measuring peripheral serotonin levels in mice with normal populations of gut bacteria and also in germ-free mice that lack these resident microbes.

The researchers found that the EC cells from germ-free mice produced approximately 60 percent less serotonin than did their peers with conventional bacterial colonies. When these germ-free mice were recolonized with normal gut microbes, the serotonin levels went back up—showing that the deficit in serotonin can be reversed. What we saw in this experiment is that they appear to depend on microbes to make serotonin—or at least a large portion of it," says Jessica Yano, first author on the paper and a research technician working with Hsiao.

The researchers next wanted to find out whether specific species of bacteria, out of the diverse pool of microbes that inhabit the gut, are interacting with EC cells to make serotonin. After testing several different single species and groups of known gut microbes, Yano, Hsiao, and colleagues observed that one condition—the presence of a group of approximately 20 species of spore-forming bacteria—elevated serotonin levels in germ-free mice.

The mice treated with this group also showed an increase in gastrointestinal motility compared to their germ-free counterparts, and changes in the activation of blood platelets, which are known to use serotonin to promote clotting.

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