How can what we eat affect our mental health?
Hippocrates nailed it with his ‘let food be thy medicine’ adage and health professionals are increasingly recognising that this wisdom extends beyond our physical condition into the realms of mental health. We instinctively know how connected our mind and body are. When we feel physically sick or are dealing with a worrying diagnosis, we undoubtedly experience low mood. Conversely, if we feel happy and excited, that niggling pain can just fade away.
It might be worth clearing up from the start, that what is on the end of our fork may not actually be ‘food’ as Hippocrates knew it. Let’s face it, we are capable of consuming almost anything one bite at a time – indeed Monsieur Mangetout, a French entertainer, once famously ate a light aircraft! Even a vegan diet can include pesticides, herbicides, preservatives, colourants, trans fats and refined sugars – all designed for maximum production efficiency and mouth appeal rather than brain health.
So how does what’s on our plate help lift depression, reduce anxiety and improve self-esteem? Here’s a gentle overview of five of the most researched mechanisms.
Nutrient Density
An optimal diet will include the full range of vitamins, minerals, fibre and amino acids drawn from a wide range of colourful, seasonal and fresh ingredients. Scientists are yet to completely understand the specific function of the myriad polyphenols, flavonoids, prebiotics and micronutrients in a single strawberry but generally agree that those consuming the widest range of fruits, vegetables, legumes, whole grains, nuts and seeds, enjoy the highest levels of Brain Derived Neurotrophic Factor (BDNF) – a protein which is positively correlated with brain plasticity and health. It follows that a diet that is high in ultra-processed foods will be deficient in vital nutrients including zinc, B12, B6 and omega-3 fatty acids.
Microbiome Diversity
We have learned a great deal about the trillions of bacteria, fungi, viruses and parasites that exist symbiotically within us – humans are essentially a multi-organism species. We call them our microbiome and tend to think of them as residing in our gut but actually they are everywhere. The diversity of this inner zoo is known to be positively correlated to sociability and stress management given that they are responsible for metabolising our food to produce the mood boosting short chain fatty acids (SCFAs) which facilitate the production of the many happy hormones and neurotransmitters that are crucial for brain health.
A poor diet, high in processed carbohydrates and sugar and low in dietary fibre, severely depletes the number and variety of these helpful microbes, compromising their production of SCFAs, contributing to reduced cognitive function and increasing anxiety and depression. Furthermore, there appears to be a trade-off. In the absence of the widest variety of good guys, some bacteria can run amok leading to issues of dysbiosis, malabsorption of essential vitamins and minerals, and suboptimal production of those mood-boosting neurotransmitters of serotonin and dopamine, and GABA which helps to calm our nerves.
pH Balance
Nowadays it seems that every other person is suffering from acid reflux and needs some sort of aid to treat their heartburn. Optimal stomach acid pH facilitates the absorption of vitamins and minerals, nourishes the gut microbiome, reduces discomfort and pain, improves sleep and energy levels, which will all improve our mood. For those still eating any meat or dairy, their body produces arachidonic acid which compromises fragile cell membrane health, a vital part of our immune system and is also associated with brain inflammation and depression. In a vegan diet, the culprits are likely to be processed oils, and for some people, gluten. Reducing these acid forming substances and prioritising sprouted grains and vegetables high in alkaline polyphenols such as dark leafy greens will generally remedy this miserable complaint.
Anti-inflammatory
A specific word about inflammation now. Inflammation is a natural immune process whereby white blood cells amass at the site of an injury in order to protect it from further harm and start the healing process. Usually, left to its own devices, the wound will heal, and the swelling will eventually disappear. However, if the injury is happening on a daily basis, caused by opportunistic bad bacteria and micro damage to our cells inflicted by many of the toxins and acids mentioned above, this inflammation can become chronic, widespread and disruptive to our finely balanced brain chemistry. Indeed, studies have proven that inflammation can cause depression and depression can cause inflammation. Cutting out these offenders and upping antioxidant rich foods including citrus and berries can douse often longstanding inflammation and improve mental health.
Reducing exposure to toxins
It is increasingly difficult to live in a toxin free environment these days and much of the food on offer at our supermarkets, due to the mass production process, is unlikely to be free from excess antibiotics, hormones, dioxins, heavy metals and pesticides which bioaccumulate in animal and non-organic plant products. Toxins have been linked to headaches, forgetfulness, moodiness and more serious neurological symptoms and behaviours, caused by reduced cerebral blood flow, high blood pressure and even damaged DNA. Detoxing all addictive substances is an obvious win, but even the ‘dirty dozen’, those twelve fruits and vegetables most regularly sprayed to encourage growth, also have to be well washed and moderated. Keep it pure and simple!
In my experience as a psychotherapist, clients who successfully address their blocks to eating for health (of which there are many) alongside talking therapy, experience a beautiful ripple effect. Simple changes increase energy and desire to exercise, often in the fresh air, which promotes better sleep, reduces stress and boosts body confidence. These adjustments combine to mitigate their risks of developing anxiety inducing chronic diseases such as certain cancers, Type 2 diabetes and heart disease, the biggest killers in the modern day. Ultimately, their improved mood, stress resilience and self-esteem enable clients to explore and process past trauma and face their future feeling empowered and self-assured.