Serotonin also has links with symptoms of nausea and vomiting. These serotonin-blocking drugs do not help with nausea caused by motion sickness. Research is in its early stages and there is limited information widely available at present. However, if any reader should discover any further information relating to the links between nausea, vomiting and serotonin - I would like to hear from them. Serotonin aids the transmission of nerve impulses to and within the brain.
Low levels cause depression and irritability.
Serotonin is derived from the amino acid, tryptophan, which is produced by the body as carbohydrates are broken down. People with low levels of serotonin experience sudden cravings for carbohydrate - a physiological response to boost serotonin levels within the brain. However, gorging on carbohydrate can help to contribute to a vitamin B6 deficiency - which is also allegedly linked to PMS, although opinions vary on this, and snacks can lead to obesity, while excess salt can increase fluid retention. These work by reducing levels of serotonin in the brain by paradoxically increasing the level of serotonin so that serotonin receptor cells lose their sensitivity to it, become more active and increase arousal levels. SSRI's prevent the serotonin being re-absorbed to maintain a steady level.