Health, Science

Food Allergies and Intolerances and Mental Health

Today is World Mental Health Day. You may be wondering why an allergy awareness and symptom tracking company like AlliApp is concerned with this, but did you know that researchers have consistently identified a link between sensitivity to food and mental health? The term ‘mental ill health’ describes conditions that affect your mood, thinking and behaviour, including depression, anxiety, bipolar disorder, autism and schizophrenia. The Diagnostic and Statistical Manual of Mental Disorders Version 5 (DSM-5) lists many more, as well as sub-categories of these conditions, but these are the most well-known.


How can food affect a condition of the mind?

Food is vital to our survival and maintenance of health. It provides energy at every level, from cellular metabolism, to the general feeling of well-being and contentment experienced after eating a tasty meal.  We know that the body is comprised of both physical and psychological components that usually work in harmony with each other. Food allergies and intolerances are mediated by our immune system, which is one such component. Therefore, it is logical that something that can physically affect us to an often alarming extent could also affect us psychologically. As general understanding of allergies and intolerances has grown, so has awareness of their impact on emotion and mental well-being, both directly and indirectly.  


One direct mechanism

The brain passes signals to its component parts, and other areas of the body via chemicals called neurotransmitters. These neurotransmitters have various effects according to their nature, but one of the main ones involved in mood regulation is called serotonin.  Scientists have emphasised the relationship between the gut and the brain. Reasons for this include the fact that both these parts of the body share many identical neurotransmitters, including serotonin. Approximately 90% of the body’s serotonin is produced by the gut despite it being a neurotransmitter [1].

Therefore, if the gut becomes inflamed due to a food allergy or intolerance, then these signals are shared with the brain.  If your digestive system is ‘unhappy’, this is transmitted to the brain. Often, people who suffer from chronic stomach complaints also suffer from lethargy and low mood [2].

Another direct mechanism

Most of the signals carried to the brain from the gut are mediated by the vagus nerves, the longest cranial nerves in the body. These nerves also have sensory functions, including relaying information to the brain from parts of the ear and throat; and providing visceral (internal organ) sensation for the oesophagus (food pipe), larynx (part of the throat), lungs and trachea (windpipe) and heart [3].  

Whatever we eat makes the journey from our mouths, all the way down our oesophagus into our gut, and from there it is metabolised by the body for our various bodily functions.  If we ingest something that causes inflammation because we cannot tolerate it, this information is transmitted throughout the body by the vagus nerves and other accessory components, including the blood stream.  Inflammatory chemicals such as histamine are released, leading to the symptoms experienced by sufferers.

These inflammatory processes can then cause a ‘cascade effect’ throughout the entire system.  If fuel from our foods cannot be metabolised efficiently, then the body cannot function efficiently, either physically or mentally.

This all sounds quite alarming, but with the right approach it can be avoided. Being aware of what you are eating and its effect on your mood and physical wellbeing is a good way to prevent this.


Indirect mechanisms

Indirect mechanisms include the anxiety that accompanies living with severe food allergies or intolerances [4].  All social occasions in our various societies are centred around food and drink – it is vital for survival, for socialisation, and for establishing relationships with others. Thus, something as simple as planning an evening out with friends, doing the weekly shop or preparing for your child to start full-time school become fraught with stress, tension, anxiety and a variety of other negative emotions.  

At times, it can almost feel as though you are locked in a ‘prison’ from which there is no escape. Recent media coverage such as the Natasha Ednan-Laperouse and Karanbir Cheema cases only serve to highlight and reinforce these anxieties. Research has shown that people affected by severe food allergies and intolerances have higher levels of depression and anxiety than those without [4,5,6]. This applies to family members as well as the individual with allergies themselves.


In conclusion

It should be noted however, that along with food allergies and intolerances, many other factors are involved in the development and exacerbation of mental illness, including genetic, environmental, and idiopathic (no known origin). The difference is that food sensitivities are relatively easier to monitor and control in comparison to these others. For many people affected by mental ill health, having awareness of this aspect of their condition together with the ability to control it can be of great help in easing their symptoms.  



  1. York Test Laboratories (2018): ‘Can Food Intolerance Cause Anxiety and Depression?’ Available online at: [Accessed 10/10/18]
  2. Healthline Media (2018): ‘Vagus Nerve Overview’  Available online at: [Accessed 09/10/18]
  3. Everyday Health (2018): ‘It’s all in Your Gut: When Depression is a Symptom of Digestive Disease’.  Available online at: [Accessed 10/10/18]
  4. Teufel M et al (2007): ‘Psychological Burden of Food Allergy’. World J Gastroenterol. 2007 Jul 7;13(25):3456-65
  5. Allergy UK (2018): ‘Types of Food Intolerance’.  Available online at:   [Accessed on 09/10/18]
  6. Hit 100 (2018):’Could a Food Intolerance be Causing Mood Swings?’ Available online at:  [Accessed 09/10/18]

Dr Nicky, PhD, MBPsS - AlliApp Science

Nicky has a background in Radiography, Neuroscience and Psychology research. She is Mum to two girls, aged thirteen and eleven; both of whom have a combination of severe food allergies, food intolerances, asthma, eczema and hay fever. As such, she has spent her entire life as a parent finding ways to manage this, with a huge focus on food preparation, educating her daughters’ peers and their families about allergy awareness, and diet.

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