Can food boost your serotonin levels?
Most of us are aware that a healthy diet is good for our mental and physical health. But some research suggests certain foods may help boost levels of serotonin, known as the ‘feel-good’ chemical. Is this true? By Sue Quinn You might have heard of serotonin. It’s a chemical messenger – known as a neurotransmitter – that’s found in the gut, brain and other parts of the body. It plays a role in everything from our sleep quality and appetite to memory and learning. And, it’s also involved in our emotions and mood. “Serotonin has a protective effect to give us resilience and reduce stress,” explains David Nutt, Professor of Neuropsychopharmacology at Imperial College London. “It’s hard to measure what levels are associated with positive mental health, and it’s likely to vary between individuals.” Low serotonin can, for some, be boosted by some antidepressant medications, Nutt says. Related stories How diet can affect your mental wellbeingCould cooking therapy help your mental health?Can changing your diet calm anxiety? How diet can affect your mental wellbeing Could cooking therapy help your mental health? Can changing your diet calm anxiety? He also believes certain foods can help protect against depression and stress because they contain tryptophan, a chemical that plays a crucial role in serotonin production. Tryptophan (sometimes referred to as l-tryptophan) is an essential amino acid – a building block of protein – that the body can’t make on its own and must be obtained through our diet. “Once digested, tryptophan is transported through the blood into the brain where it gets converted to serotonin,” Nutt says. In the UK, there is no recommended daily intake of tryptophan and for most people, only small amounts are necessary to stay healthy. There is research which suggests consuming tryptophan-rich foods alongside carbohydrates can boost the amount of tryptophan absorbed by the brain. So, what foods can you find it in? Tryptophan-rich foods Tryptophan is found in a wide variety of plant and animal foods that contain protein. Quinoa, soy, red meat, chicken, fish, eggs and cheese contain all nine of the essential amino acids the body can’t make, including tryptophan. This healthy berry banana smoothie comes with sunflower seeds and oats So, the big question: If you eat foods that are rich in tryptophan will you be able to help protect your mental health? There is research which highlights that people who have increased their intake of tryptophan-rich foods have reported fewer symptoms of depression and better mood. And likewise, some studies have shown people experiencing depression have low tryptophan levels. On top of this, some research also suggests people with low tryptophan may experience more panic and anxiety than those with normal levels. “We also know that low protein diets… can lead to low levels of tryptophan and puts a strain on the production of serotonin in the brain,” Nutt says. “Dietary restriction for just a few weeks can lead to changes in serotonin function in the brain consistent with lower serotonin production.” This evidence suggests that for some people, boosting their intake of tryptophan rich foods might protect against depression, Nutt says. However, tryptophan alone can’t lift depression, he stresses. “But it can help prevent it, especially in people with a vulnerability to depression.” Not all the tryptophan we consume enters the brain and is converted into serotonin. “So, the more tryptophan in the diet, the more likely any molecule is to get across the blood brain barrier and into the brain,” Nutt says. Likewise, consultant psychiatrist Dr Nick Walsh says boosting your intake of tryptophan-rich foods can’t improve mental wellbeing on its own but may do as part of a healthily balanced diet. That’s because serotonin production is highly complex and relies on a multitude of other nutrients including vitamins and minerals. “To increase your serotonin levels by making some changes that are consistent with a healthy, balanced diet is a good thing to do,” Dr Walsh says. “But on its own, it’s not sufficient.” He recommends consuming tryptophan-rich foods in their whole, unprocessed form, reducing your intake of refined sugar and looking after your gut health. It’s highly debated though… While serotonin is widely acknowledged to influence our mood and emotions, not all experts agree that low levels directly cause depression. In fact, UCL scientists have explained ‘there remains no clear evidence that serotonin levels or serotonin activity are responsible for depression’. Other scientists argue there’s no robust evidence that boosting our intake of foods rich in tryptophan can improve our mental health. Professor Allan Young, director for affective disorders at King’s College London, says for some people, tryptophan can work as an anti-depressant, but research has focussed on high-dose supplements, not food. “Studies have involved supplements at much higher doses than you would get from any dietary intake,” Young says. Professor Felice Jacka, director of the Food and Mood Centre, at Melbourne’s Deakin University is also sceptical. Tryptophan needs to be transported from the bloodstream into the brain by certain amino acids, she says. But it has to compete for this transport with other proteins in the food we eat, which restricts the amount that gets through. “Indeed, even a tiny amount of protein in foods is enough to prevent an increase in tryptophan and even high-carbohydrate foods typically still contain enough protein to have this effect,” she says. Microbes in the gut are thought to play a major role in how serotonin is processed, too. “But scientists aren’t clear,” Jacka says. “It’s very complex and a lot is unknown.” Ironically, it could be that high-carbohydrate foods – not those containing tryptophan – increase serotonin in the brain, Jacka says. The theory is that when we eat carbohydrates the body releases insulin, and excessive insulin causes tryptophan to move into the brain. This explains why it’s sometimes suggested to combine tryptophan-rich foods with carbohydrates. While it seems that science still needs to learn more about the impact of tryptophan-rich foods on mental health, Dr Walsh advises: “What is important is eating a balanced diet that supports the gut microbiome, and where you get a full range of nutrients.” If you or someone you know is concerned about your mental health, help and support is available. Originally published October 2024