Eating a large turkey dinner may actually make you happy. Turkey contains tryptophan, a precursor chemical for the neurotransmitter serotonin, a chemical responsible for elevated moods. Unfortunately, many people experience a condition known as serotonin depletion, where levels of serotonin drop to very low levels, leading to depressed moods. Genetics, food, drugs and lifestyle choices can all affect serotonin levels, although various medications can help control its effects.
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You cannot eat serotonin, but you can eat foods rich in the amino acid tryptophan, which leads to increased serotonin production. Tryptophan competes with other amino acids in your blood to enter the brain. These other amino acids are cleared by the release of insulin after a high carbohydrate meal, increasing the amount of tryptophan able to enter your brain cells. Once inside your brain, tryptophan is converted to 5-hydroxytryptophan or 5-HTP. 5-HTP is then converted to 5-HT, also known as serotonin. Eating sweets, breads, pastas or other high carbohydrate foods often increases your mood as it increases serotonin levels in your brain.
While increased serotonin levels are associated with elevated moods, serotonin depletion results in negative mood states. Common negative mood states include anxiety, excessive worry, panic and fear. However, people express negative moods in different ways. Some people experiencing serotonin depletion may feel pessimistic, irritated or impatient, while still others may have obsessive-compulsive or suicidal thoughts. These negative thoughts can unfortunately lead to negative behaviors such as aggression.
Drugs Affecting Serotonin Levels
Many drugs can affect serotonin levels in the body. Alcohol, nicotine and marijuana cause a burst in the release of serotonin by your neurons, resulting in an initially elevated euphoric mood. However, once the initial feeling of euphoria fades, serotonin levels drop lower than they were originally, a significant serotonin depletion. Often, this leads to continued drinking or smoking in a futile effort to regain the initially heightened serotonin levels.
Caffeine, unlike alcohol, lowers serotonin levels as well as decreases your appetite for carbohydrates, further decreasing your ability to synthesize additional serotonin. If your serotonin levels are naturally low, caffeine exacerbates the situation, which may explain why some people feel down after having a bit more coffee than usual.
Causes of Serotonin Depletion
Serotonin depletion has many causes. While a high-carbohydrate diet and certain drugs can cause serotonin depletion, naturally low levels of serotonin may be also be genetic. Genetically low levels of serotonin may be due to deficient levels of serotonin precursors such as tryptophan or 5-HTP. Sufferers lack enough starting product to make adequate serotonin, even if their body signals its production. Other genetic causes include an overactive metabolism of serotonin once it is released. People may be able to synthesize it, but they break it down too quickly, limiting its effects.
Serotonin depletion can be treated by drugs known as selective serotonin reuptake inhibitors, or SSRIs. SSRIs block the reuptake of serotonin in the brain, leaving any amount that was released around longer than usual. The overall effect is similar to releasing larger amounts of serotonin. Prozac, also known as fluoxetine, is one example of an SSRI.
Other treatments include monoamine oxidase inhibitors or MAOIs. Monoamine oxidase is an enzyme responsible for the breakdown of serotonin. Decreasing the amount of enzyme that breaks down serotonin increases the amount of time serotonin is available to stimulate neurons. An example of an MAOI is benmoxin.
Serotonin depletion may also be treated by an over-the-counter pill containing 5-HTP, a precursor to serotonin. This may be particularly useful for individuals with a genetic deficiency of serotonin due to low levels of precursor products.
- The Geek's Guide to Practical Brain Chemistry: Neurons and Neurotransmitters
- Hedweb Good Drug Guide: Tryptophan Depletion Alters the Decision-Making of Healthy Volunteers Through Altered Processing of Reward Cues
- Psychiatric News: Depression-Serotonin Link--Many Mysteries Remain
- Clinical Neuroscience Research Center UCSD: Serotonin--It's Possible to Have Too Much of a Good Thing
- My Yoga Online: Serotonin and Depression