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The relationship between what you eat and your mental health

By Gianluca Tognon | Sep 14, 2021


Is there a link between diet and depression?

Who has never felt a little depressed from time to time? I guess very few people can answer “yes” to this question. Depressive feelings are a normal part of everyone’s life, and we learn to accept this reality while we grow up.

With everything your employees have had to deal with over the last 18 months of the pandemic it's hardly surprising either.

However, things are different when these feelings evolve from occasional to regular and develop into a clinical depression diagnosis. 

Doctors and researchers still ignore the causes of this health condition, although it’s clear that its causes are likely to be multiple.

In particular, an unfortunate combination of biological, genetic, social, lifestyle, and environmental risk factors can contribute to the onset of depression. Past stressful experiences do also add a toll.

Because its root causes are still unknown, the current treatments for depression can be stressful for many patients and not necessarily successful.

Many people take supplements in the hope that they will contribute to making them feel better. However, any positive effect of nutrient supplementation has yet to be confirmed by science.

On the other hand, the idea that eating specific foods (like chocolate, for instance) could contribute to a better mood has no foundation either.

As with other food products of the like, chocolate can probably contribute to a better mood just for a few seconds while eating it. Still, any positive feelings disappear as soon as you have eaten up your favourite treat.  

What does the research say?

The hypothesis that a specific diet could contribute to a better mood is fascinating, and many researchers have investigated this topic.

Unfortunately, their studies were not always well-designed (i.e., they didn’t rigorously plan these studies in a way to reduce bias to a minimum).

Aimed to fill in some of the knowledge gaps in this field, the European collaborative investigation “Mood food” was launched some years ago. It involved several researchers in different countries, including researchers from the London University College.

The “Mood food” study concluded that a balanced diet rich in wholegrain, fruit, vegetables, legumes, fish, and olive oil (but poor in meat, highly-processed foods, and alcohol) could reduce the future risk of depression.

The researchers also concluded that obesity is a crucial risk factor for this health condition.

I’m a bit disappointed by these results, not because I do not support a healthy and balanced diet, but because I was hoping for some more specific outcomes from this extensive study.

Obviously, these results are relevant for public health policies aimed to promote greater adherence to the Mediterranean diet.

My point is that they don’t say much about which diet works to treat an ongoing depression. 

Specific nutrients and how they affect mental health

We can understand more of the mechanisms linking diet to the risk of depression by digging into the nutrients that are most likely to affect mental health.

Several of the nutrients that can be found in a Mediterranean-like diet can positively influence mental health.

These nutrients include unsaturated fats (particularly omega-3, which are a component of cell membranes in the brain), phospholipids, and the following vitamins: niacin, folate, vitamin B6, B12, and D.

Therefore, foods like fish, green vegetables, nuts, and seeds are a must if you want to improve your mood.

Notably, patients with age-related memory impairment (which is clinically defined as stage 1a dementia) tend to have lower levels of omega-3 fatty acids in their blood.

The same goes for type 1b dementia patients, who suffer from a mild cognitive impairment.

The brain is particularly vulnerable to oxidative stress. This is the reason to recommend foods rich in antioxidants (fruit and vegetables, especially those rich in vitamins A like carrots, C like citrus fruits, and E like olives and nuts) for better mental health.

Many mental diseases are related to low blood levels of antioxidant vitamins, such as autism, ADHD, bipolar disorder, depression, schizophrenia, and even substance abuse.  

On the other hand, saturated fat and simple sugars can increase the risk of mental illness.

However, I guess you would probably swear that there is nothing better than having a dessert to feel better immediately!

The reason why a high sugar intake is mainly related to decreased mental health is less apparent, though.

However, we know that people with diabetes have a higher risk of dementia compared to non-diabetic subjects. Also, high glucose and glycated haemoglobin levels inversely correlate with memory capacity.

The ketogenic diet

Speaking of sugars, I noticed that recently some studies had been published on the effect of a ketogenic diet (which almost excludes all sugars) on depression.

The ketogenic diet is considered attractive for the treatment of mental conditions because it has been used for treating epilepsy since the 1920s.

Scientists have observed that half of the individuals treated with this diet saw the number of seizures go down by half. The latter effect is likely due to the calming effect exerted on the brain by ketone bodies, which the body produces as an alternative energy source when you exclude all sorts of carbohydrates from your diet.

Therefore, intervention studies have studied the applications of the ketogenic diet to the treatment of depression.

A recent Cochrane panel review summarised the results of eight of these studies, selected based on their scientific quality.

The panel concluded that there is some evidence favouring a beneficial effect of a ketogenic diet on depression. However, the studies published so far included only a few subjects and had other limitations. The ketogenic diet is relatively well tolerated but challenging to sustain for a prolonged time.

One of the things we need to consider when judging the above results is that depression is more common among overweight and obese people.

The ketogenic diet is effective in reducing body weight quickly. Therefore, I suspect that part of the beneficial effects I mentioned above are probably related to the positive impact that this type of diet has on body weight. This effect can also be consequent to a healthy and balanced diet. 

Anyway, there are also reasons to believe that the influence that the ketogenic diet has on the hormonal balance also plays a role in this game. For instance, this type of diet influences the production of several neurotransmitters, including dopamine, noradrenaline, and serotonin. Improvements in the vascular system can also result in a better mood. 

The importance of good hydration

Another inspiring but controversial topic is the possible influence of hydration status on mood and cognitive ability in general.

Although researchers have only started investigating this topic, we know that severe dehydration causes cognitive deficits and mood disturbance.

On the other side, water consumption seems to improve not only mood but also visual attention.

Although more studies are needed in this field to clarify whether a minor dehydration status can also influence mood and particularly on the risk of depression, I think drinking an extra glass of water every day is still a good idea to cheer you up.

So encouraging your employees to drink water frequently is going to be good for their health - and their productivity!


To conclude, let’s depict an immediate action plan to improve your diet, prevent chronic disease, and end up with a better mood as a bonus:

  • First of all, set healthy goals such as doubling the amount (and the number of types) of vegetables you eat daily
  • Start with positive goals (e.g., more fish and and less meat)
  • Drink a glass of water every morning when you wake up
  • Build a support network: who among your family members, colleagues and friends wants to improve their lifestyle? Maybe you can exchange tips and encourage each other!
  • Remove distractions when you eat
  • If you miss one goal from time to time, don’t worry, it’s not the end of the world!

Finally, I will never stress enough how vital self-monitoring is. Keep a food and mood journal; it will help you understand which foods make you feel better and see if you can identify any exciting patterns in the food you eat.

Stay tuned for more updates on diet and mental health!





  1. Mood Food - Preventing Depression through Food. A guide for dieticians. Downloadable from www.moodfood-vu.eu 
  2. Mood Food - Eating for mental health. Preventing depression through food. Downloadable from www.moodfood-vu.eu
  3. Masento NA, Golightly M, Field DT, Butler LT, van Reekum CM. Effects of hydration status on cognitive performance and mood. Br J Nutr. 2014 May 28;111(10):1841-52.
  4. Lim SY, Kim EJ, Kim A, Lee HJ, Choi HJ, Yang SJ. Nutritional Factors Affecting Mental Health. Clin Nutr Res. 2016 Jul;5(3):143-52.
  5. Brietzke E, Mansur RB, Subramaniapillai M, Balanzá-Martínez V, Vinberg M, González-Pinto A, Rosenblat JD, Ho R, McIntyre RS. Ketogenic diet as a metabolic therapy for mood disorders: Evidence and developments. Neurosci Biobehav Rev. 2018 Nov;94:11-16.
Gianluca Tognon

Gianluca Tognon

Gianluca Tognon is an associate professor in public health at the University of Skövde (Sweden) and the founder of the consulting company “The Food Scientist”. He is an expert in public health, nutrition, and food science.