Serotonin foods: what food can and cannot do for your mood

Georgina Waugh, Clinical Nutritionist (BHSc Nutritional Medicine) · 10 minute read · Updated 8 June 2026

Serotonin foods are a real search and a false promise: no food raises the serotonin in your brain. Not bananas, not turkey, not any of the usual list. That does not mean food and mood are unrelated, because one good trial says otherwise, but what worked in it was not a list of foods.

Search the phrase and you get the same handful of items on every page. It is the wellness noise problem in miniature, so I would rather give you the mechanism. Once you have it, the list stops making sense on its own.

The line most of us were taught is that protein builds serotonin, so eat protein and your mood follows. It is a line I have written myself. When I went back to the human studies for this piece, the ratio that protein actually moves turned out to run the other way.

The short version

• Serotonin in food does not reach your brain. The serotonin in a banana is real and it stays outside the blood-brain barrier.
• About 95% of the serotonin in your body is made in your intestine, doing a completely different job.
• A protein-rich meal lowers the blood ratio that lets tryptophan into the brain rather than raising it, so the high-protein advice has it backwards.
• When researchers deliberately stripped tryptophan out of healthy volunteers, their mood did not drop.
• The one trial that improved depression with food changed a whole diet over 12 weeks, on top of the care people were already getting. Large trials of fish oil, vitamin D and multinutrient capsules found nothing.
• If your mood has been low for two weeks or more, that is a GP appointment, not a shopping list.

Do serotonin foods actually raise serotonin?

Serotonin has a reputation as a brain chemical, and most of it is nowhere near your brain. Reviewing the physiology in 2017, Terry and Margolis put it plainly: 95% of the body's serotonin is produced in the intestine.

That gut serotonin is not a spare tank for your mood. It works locally, on how the bowel moves and how the gut wall responds to what is in it, and it does not travel up to become the serotonin that antidepressants act on.

The brain makes its own, from tryptophan, an amino acid you do get from food. So the real question is not whether food contains serotonin. It is whether food can get tryptophan into the brain.

The protein advice runs the wrong way

Tryptophan is the least abundant amino acid in protein, and it enters the brain on a transporter it shares with several other large amino acids. They compete for the same door. What matters is not how much tryptophan is in your blood, but how much there is relative to everything queueing beside it.

Eat a protein-rich meal and you raise all of them. Tryptophan loses the race.

Wurtman and colleagues measured this in 2003. Nine adults, fasted overnight, ate a carbohydrate-rich breakfast on one day and a protein-rich breakfast on another, with blood taken at baseline and four times over the next four hours. Among the eight who ate both, the median difference in the tryptophan ratio was 54%, and it was the protein breakfast that sat lower.

Writing in the Journal of Psychiatry and Neuroscience, Simon Young put it more bluntly than I would dare to: "The idea, common in popular culture, that a high-protein food such as turkey will raise brain tryptophan and serotonin is, unfortunately, false." The same paper deals with the banana, which does contain serotonin, and which does not get it past the blood-brain barrier.

Do not run too far the other way with this. Nine adults, two breakfasts each, is a small study, it measured a ratio in blood rather than anything in a brain, and the authors wrote only that the meals "probably" change brain serotonin synthesis. It is enough to retire the protein claim. It is not a reason to eat toast for your mood.

What happens when serotonin is deliberately lowered

There is a way to test the whole idea, and researchers have been using it for decades. You give someone a drink of amino acids with the tryptophan left out, their tryptophan ratio falls sharply for a few hours, and you watch what their mood does. It is called acute tryptophan depletion.

Ruhé, Mason and Schene pooled these studies in Molecular Psychiatry in 2007. They found 73 of them and were able to meta-analyse 45.

In healthy people, lowering serotonin did not lower mood.

It did lower mood slightly in healthy people with a family history of depression, moderately in people who had been depressed themselves, recovered and were off medication, and it brought symptoms back in people in remission who were taking a serotonergic antidepressant. The authors' own conclusion is that the studies "fail to demonstrate a causal relation" and probably describe a vulnerability rather than a mechanism.

Serotonin is not a fuel gauge that empties when you eat badly and fills when you eat well.

The one food trial that moved depression

Now the other side, and it is Australian.

The SMILES trial ran out of Deakin University and was published in BMC Medicine in 2017. Researchers screened 166 people and randomised 67 adults with moderate to severe depression. One group had seven sessions with a clinical dietitian over 12 weeks. The other had social support on exactly the same schedule, so that attention alone could not explain the result.

The detail people skip is the one that matters most. Fifty-five of the 67 were already receiving care: 21 having both psychotherapy and medication, nine psychotherapy alone, and 25 medication alone. The diet went on top. Nobody stopped anything.

Sixty-seven Australian adults with moderate to severe depression, randomised to seven sessions with a dietitian or to social support on the same schedule, for 12 weeks. At the end, 10 of the 31 in the diet group scored under 10 on the MADRS depression scale, against 2 of the 25 controls. The pale part of each bar is everyone else, and in both groups it is the majority. Jacka and colleagues, BMC Medicine, 2017.

Remission at 12 weeks was 32.3% in the diet group and 8.0% in the control group. In the trial's own arithmetic, about four people would go through the program for one extra remission.

That is a genuinely good result and it deserves its caveats. Sixty-seven people is small. Nobody could be blinded to whether they were seeing a dietitian. The confidence interval around that figure of four runs from 2.3 to 27.8, which is very wide. The trial has been argued over in print ever since, and it has never been repeated at scale.

It is still the best evidence there is that changing what somebody eats can shift depression symptoms. And what changed was a whole diet for three months, not a snack.

What happened when the same idea was put in a capsule

If food helps because of a nutrient, the nutrient in a capsule should help too. That has been tested properly, in numbers the diet trial can only dream of.

The trial	What it tested	What it found
SMILES, 2017	67 adults with moderate to severe depression, seven dietitian sessions over 12 weeks, alongside usual care	32.3% reached remission, against 8.0% on social support
VITAL-DEP fish oil, 2021	18,353 adults aged 50 and over, one gram of marine omega-3 daily for a median 5.3 years	Slightly more depression on the supplement, 13.9 against 12.3 cases per 1,000 person-years, and no difference in mood scores
VITAL-DEP vitamin D, 2020	The same 18,353 adults, 2,000 IU of vitamin D3 daily over the same period	No difference, 12.9 against 13.3 cases per 1,000 person-years
MooDFOOD, 2019	1,025 overweight adults with mild depressive symptoms, a daily multinutrient capsule for a year	10% developed major depression, and the capsule did not change that

Read the four rows together and a pattern falls out. The study that changed what people ate found something. The studies that handed people a capsule did not, across more than 19,000 participants.

The fish oil result is the one people misquote in both directions. Risk was slightly higher on the supplement, but mood scores were identical between the groups, so the honest reading is no benefit rather than harm.

None of that makes the nutrients useless, and I am not coming for your fish oil. It means a capsule has very little to work with in a population that is mostly not short of anything. The other half of that question is the form on the label, which is what I went through in the methylated multivitamin piece.

What I see in clinic. The pattern I meet most often is a woman who has been flat for months, has fish oil and vitamin D and a magnesium powder in the cupboard, and has never had her ferritin checked. She has not done anything silly. She has done the things the internet told her to do, in the order the internet told her to do them.

When we go back and get the ordinary bloods, a reasonable proportion of the time there is something in them. When there is not, that is worth knowing too, because it moves the conversation to sleep, to alcohol, to how little is actually going in before 2pm, and to whether this is a conversation for her GP rather than for me.

The capsules were not the problem. The order was.

Nothing on this bench raises brain serotonin, and I would still put this breakfast in front of you. The trial that worked changed the whole pattern of what somebody ate for three months, which looks a lot more like a bench than like a list.

When it is not a food question

This is the part I will not soften.

In the Australian Bureau of Statistics National Study of Mental Health and Wellbeing, 21.5% of Australians aged 16 to 85 had a mental disorder in the 12 months before they were surveyed, and 42.9% had at some point in their lives. Among women the 12-month figure was 24.6%. This is common, it is medical, and it responds to proper care.

Healthdirect sets the threshold clearly: if the signs have been there for two weeks or more, it is time to get help from a health professional. Two weeks, not two years, and not once it gets bad enough to feel like it justifies the appointment.

Nothing in this article is an alternative to that, and SMILES is the argument rather than the exception: the diet worked as something added to medication and therapy, in people who kept receiving both.

If you are in immediate danger, call 000. If you need to talk to someone tonight, Lifeline is 13 11 14 and answers 24 hours.

There is also a set of ordinary physical things that produce a flat, unmotivated, foggy few months and are cheap to check. Low iron stores, an underactive thyroid and low B12 all do it, and none of them can be sorted out by reading an article, including this one.

What to do this week, without buying anything

The order is the useful part.

1. If it has been two weeks or more, book the GP. That is Healthdirect's threshold, not mine, and appointments are often three weeks out, so book it before you feel ready.
2. Keep a note while you wait. Mood out of ten at the same time each day, roughly what you ate before 2pm, what time you went to bed. Two weeks of that tells a GP more than any single number.
3. Ask for the ordinary bloods by name: full blood count and iron studies including ferritin, thyroid function, B12 and folate, and vitamin D if you fall into a rebated category.
4. Change one meal rather than your whole diet. For most of the people I see it is the meal they currently skip, and our free micronutrient calculator will cost out an ordinary day in a minute.
5. Look at alcohol honestly for a fortnight. It is a depressant, and it is the one thing on this list that costs nothing to test.

And before you buy anything, ask yourself:

• Has this been two weeks, or has it been two years?
• When did I last have my ferritin, thyroid and B12 checked?
• Am I eating anything at all before 2pm on an ordinary work day?
• How much am I actually drinking in a normal week?
• If a supplement was going to work, what would change, and by when would I know?

If your bloods have already come back normal and you still feel like this, I have written that one separately: why you can be exhausted with a normal blood test. If the phrase you have landed on is that your nervous system is dysregulated, that one is here too, and what we look at as a clinic is on the mood, stress and sleep page.

Not sure which of these is you?

If you have a folder of results and a cupboard of supplements and no clear idea which thread to pull, that is a fifteen minute conversation, not a purchase. I will tell you honestly if the answer is your GP.

Book a free 15-minute call

General information only, and never a replacement for medical advice.

Common questions

Is there a link between food and mood?

Yes, but it is a link between an overall pattern of eating and mood, not between single foods and single chemicals. The strongest evidence is the SMILES trial, where 12 weeks of dietitian-supported dietary change alongside usual care produced remission in 32.3% of people against 8.0% on social support.

Which foods improve mood?

No individual food has been shown to improve mood on its own. What has been tested is a whole diet: more vegetables, fruit, wholegrains, legumes, fish, olive oil and unsalted nuts, and less of the highly processed end. That pattern is what changed in the one trial that worked, over three months.

How can I raise my serotonin levels quickly?

You cannot raise brain serotonin with food, quickly or slowly. Tryptophan competes with other amino acids to enter the brain, so a protein-rich meal lowers the ratio rather than raising it, and serotonin already present in food does not cross the blood-brain barrier. Medicines that act on serotonin are prescription decisions.

Where is 90% serotonin in the body?

In the gut. A 2017 review puts it at 95% produced in the intestine, where it acts locally on how the bowel moves rather than on mood. That gut serotonin does not travel to the brain, which is why a blood or stool serotonin result tells you nothing about how you feel.

What is the best supplement for increasing serotonin levels?

I cannot answer that in an article, and the trial evidence is not encouraging. Three large randomised trials of fish oil, vitamin D and a multinutrient capsule found no reduction in depression across more than 19,000 people. Anything acting on serotonin can interact with prescribed medicines, so that is a question for your GP or pharmacist.

What does a lack of serotonin feel like?

There is no test for it and no agreed symptom picture, which is worth knowing before you buy something aimed at it. When researchers lowered serotonin deliberately in healthy volunteers, mood did not change. Low mood is real; the low-serotonin explanation for it is far shakier than the internet suggests.

Sources

1. Terry N, Margolis KG. Serotonergic mechanisms regulating the GI tract. Handbook of Experimental Pharmacology 2017;239:319-342.
2. Young SN. How to increase serotonin in the human brain without drugs. Journal of Psychiatry and Neuroscience 2007;32(6):394-399.
3. Wurtman RJ, Wurtman JJ, Regan MM, et al. Effects of normal meals rich in carbohydrates or proteins on plasma tryptophan and tyrosine ratios. American Journal of Clinical Nutrition 2003;77(1):128-132.
4. Ruhé HG, Mason NS, Schene AH. Mood is indirectly related to serotonin, norepinephrine and dopamine levels in humans: a meta-analysis of monoamine depletion studies. Molecular Psychiatry 2007;12(4):331-359.
5. Jacka FN, O'Neil A, Opie R, et al. A randomised controlled trial of dietary improvement for adults with major depression (the SMILES trial). BMC Medicine 2017;15:23.
6. Okereke OI, Vyas CM, Mischoulon D, et al. Effect of long-term supplementation with marine omega-3 fatty acids vs placebo on risk of depression. JAMA 2021;326(23):2385-2394.
7. Okereke OI, Reynolds CF, Mischoulon D, et al. Effect of long-term vitamin D3 supplementation vs placebo on risk of depression. JAMA 2020;324(5):471-480.
8. Bot M, Brouwer IA, Roca M, et al. Effect of multinutrient supplementation and food-related behavioral activation therapy on prevention of major depressive disorder. JAMA 2019;321(9):858-868.
9. Australian Bureau of Statistics. National Study of Mental Health and Wellbeing, 2020-2022.
10. Healthdirect Australia. Depression.

Important: This article is general information written by a clinical nutritionist. It is not medical advice and does not replace care from your GP, psychologist or psychiatrist, and nutrition does not diagnose, treat, cure or prevent depression, anxiety or any other mental illness. If your mood has been low for two weeks or more, please see your doctor. In an emergency call 000; Lifeline is 13 11 14.

Written and reviewed by Georgina Waugh

Clinical Nutritionist, BHSc Nutritional Medicine

Last updated: 8 June 2026

Sources reviewed: Four randomised trials including the Australian SMILES trial, a meta-analysis of tryptophan depletion studies, two journal reviews, and current ABS and Healthdirect guidance.