What is Serotonin?
Serotonin (5-hydroxytryptamine or 5-HT) is a naturally occurring substance in the human body. It is primarily considered a neurotransmitter that sends messages and signals along and between our nerves. However, serotonin is also regarded as a chemical or hormone responsible for our moods and emotions. It is predominantly found in the brain, bowels and blood.
As serotonin can be found widely across the body, it is believed that the chemical plays a role in influencing a variety of body and psychological functions. Serotonin is thought to be extremely helpful in constricting smooth muscles, transmitting impulses between nerve cells, regulating cyclic body processes (including hormones), and contributing to wellbeing and happiness. Studies have even found links between serotonin and bone metabolism, breast milk production, liver regeneration and cell division.
Serotonin is manufactured in the intestines and brain. The majority of serotonin can be found in the gastrointestinal tract (around 90%), which is why gut health is crucial for mood and mental stability. It is thought that serotonin can affect mood and social behaviour, appetite and digestion, sleep, memory, sexual desire and function. A high association has also been made between anxiety, depression, anger and serotonin. Some ways to increase body serotonin levels include sunlight (Vit D), exercise, and diet.
Important functions of serotonin
As a neurotransmitter, serotonin affects a range of bodily processes both directly and indirectly. The following is a list of functions and conditions that serotonin can influence:
Bowel function. Most of the body's serotonin is found in the gastrointestinal tract where it regulates bowel function and movements. Serotonin also plays a part in reducing appetite while consuming a meal. Suffice it to say that good gut health = improved bowel function.
Mood. Serotonin is classified as one of the four ‘happy hormones’ (along with endorphins, dopamine, and oxytocin). It is most well-known for its role in regulating mood and emotions. When serotonin levels are low, you can be more prone to anxiety and depression.
Clotting. Another important function of serotonin is in the formation of blood clots. Serotonin is released by blood platelets when there’s a wound. The resulting vasoconstriction (narrowing of the tiny arteries or arterioles) reduces blood flow and promotes clotting.
Nausea. Serotonin comes to the defence when you eat something that’s toxic or irritating. More serotonin is produced in the gut to increase transit time so the irritant is expelled via the bowels. This increase in blood serotonin levels also causes nausea by stimulating the area postrema (nausea area in the brain).
Gut health support and a detox help regulate serotonin levels. Happy Greens is excellent for this – helps with nausea, too!
Bone density. Studies have shown that a persistently high level of serotonin in the bones can increase your risk for osteoporosis. Maintaining adequate levels of Vitamin D, magnesium and calcium in whole foods can help with this.
Sexual function. Low serotonin levels are thought to contribute to a decrease in libido.
Premenstrual syndrome (PMS). There’s research indicating serotonergic functioning during the luteal phase of the menstrual cycle in women with PMS and PMDD. A decrease in the platelet uptake of serotonin was observed, with lower serotonin levels in the blood during the last 10 days of their cycle. There is also evidence to suggest that oestradiol may regulate serotonin receptors and their function.
How serotonin is produced
Serotonin is naturally produced in the body through the biochemical conversion of a protein component known as tryptophan. The flowchart of serotonin production would be something like this:
PROTEIN → L-TRYPTOPHAN → SEROTONIN → MELATONIN
As you can see from the flow chart above, serotonin is actually a precursor of the hormone melatonin. We all know that melatonin is crucial in achieving a good night’s rest, which is why a serotonin imbalance can also lead to sleep problems. Diets lacking in tryptophan may cause people to have low serotonin levels and experience depression, headaches and sleep disorders.
To have the correct flow of serotonin, you need many micronutrients and co-factors such as B vitamins, vitamin C, zinc, magnesium, iron, 5-HTP, and antioxidants. Proper absorption of these nutrients is also crucial and may be achieved with the correct gastrointestinal tract (GIT) microbial support such as digestive enzymes, prebiotics and probiotics.
Because the highest levels of serotonin are found in the digestive system, certain foods may raise or lower serotonin levels. With this understanding, you can actively balance gut health and include lots of serotonin-rich foods in your diet.
How to naturally produce more Serotonin
Foods that contain the essential amino acid tryptophan can assist the body in producing more serotonin. So what does a serotonin-rich diet look like? It can include the foods listed here:
Grains. Wholemeal grains are high in B vitamins which are essential for serotonin production. Brown rice, quinoa, and millet are among the best options.
Fish. Salmon, fresh tuna, snapper, sardines, herring, mackerel and halibut are high in tryptophan and excellent sources of serotonin.
Organic Poultry. Chicken and turkey are excellent sources of the tryptophan necessary for serotonin to stay at an optimal level in the brain and body.
Organic Meat. Beef, lamb and liver provide amino acids and other nutrients that facilitate the creation of serotonin.
Nuts and Seeds. Walnuts are especially beneficial for serotonin production. Flaxseeds, hemp seeds, sunflower seeds, pumpkin seeds, sesame seeds, pecans, almonds and hazelnuts can also increase serotonin levels.
Oils*. Essential fatty acids increase serotonin production. These include the omega-3 fatty acids found in fish, walnut and flaxseed oil. Grapeseed, safflower, sunflower and wheat germ oils are also great sources of omega-6 fatty acids. Additionally, gamma-linoleic acid is found in spirulina or blue-green algae, black currant, evening primrose and borage oils.
(*Always try to get cold-pressed, organic oils when possible.)
Dairy. Eggs are rich in protein and contain amino acids and essential fatty acids necessary to produce serotonin. Egg whites are ranked very high on the serotonin food list. Lower levels of tryptophan are found in milk and some cheeses. Cottage cheese and yoghurt are also good foods to eat to increase and maintain your serotonin levels. Take note, however, that dairy consumption must be closely monitored. Also, try to buy organic dairy products.
Fruits. Bananas, kiwi, pineapple, plantains, plums, grapefruit, mango, honeydew and cantaloupe have a high serum concentration, which makes them very useful in serotonin production. Tomatoes and avocado are also rich in nutrients necessary for serotonin to develop and reach optimal levels in the brain.
Vegetables. Broccoli, cauliflower and green leafy vegetables such as spinach are serotonin-rich, as are baked potatoes with skin, mustard greens and mushrooms.
Sea Vegetables. Kelp, seaweed and spirulina (blue-green algae) contain tryptophan, an essential amino acid that’s vital for creating serotonin in the brain.
- Legumes & Beans. Lentils, mung beans, chickpeas, peas, and cooked beans – kidney, black, lima, navy and pinto – are good sources of serotonin.
Take the first step to a healthy balance
Now that you know how serotonin literally impacts most, if not all, bodily processes – from appetite and digestion to mood, memory, sleep and sexual function – it’s time to get those serotonin levels in check.
Take a look at the Happy Hormones 8-Week Program, a comprehensive tool that will teach you how to make the right food choices and implement healthy habits so you can achieve optimum health and wellness for life. Best of all, it’s FREE!
Karuna Singh. Nutrient and Stress Management. Journal of Nutrition & Food Sciences. 2016, 6:4.
Wallace, C.J.K., Milev, R. The effects of probiotics on depressive symptoms in humans: a systematic review. Annals of General Psychiatry. 2017 16:14. https://doi.org/10.1186/s12991-017-0138-2
Murphy, S.E., Longhitano, C., Ayres, R.E. et al. Tryptophan supplementation induces a positive bias in the processing of emotional material in healthy female volunteers. Psychopharmacology. 2006. 187:121–130. https://doi.org/10.1007/s00213-006-0401-8