We have known about the connection between the gut and the brain for a little while now but more recently there has been an explosion of research into the effect of your diet on your mental health. Perhaps you instinctively know that what you eat affects how you feel — for instance, that when you eat plenty of vegies and are well hydrated, so too are you energised and balanced. Alternatively, when you go a little crazy on the sugar, you might see that reflected in your behaviour, your mood or your digestion.
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What we have not had until recently, though, is solid evidence that diet can directly affect mental health, supported by specifically designed intervention trials. It is therefore wonderful to see this evidence published, shining a light on this relationship that is so important.
What you can take from this is that what you eat is just as important as what you don’t eat. The issue at large is that for many people their current balance is out and we are, as a population, eating too much of the food that is not beneficial to us and not enough of that which will nourish and sustain us. The effects of this are visible in our own health and in that of the entire food system and the environment.
The gut-brain link
So what can we eat to support our brain, our mental health and our entire nervous system? One prominent study from 2017, the SMILES trial, showed that participants experiencing depression who ate diets rich in vegetables, fruit and wholegrains, with a focus on oily fish, legumes, extra virgin olive oil and raw, unsalted nuts and seeds, noticed a significantly improved mood. In some cases the participants in this 12-week trial went into complete remission, no longer experiencing any depressive symptoms.
This is fantastic news, given the accessibility of these foods both in cost and availability. Again, this is perhaps not new information for us but it’s the first time we’ve seen concrete evidence to back up the common sense.
When we look into how these foods contribute to our happiness and calmness, it is a work in progress and we are making new discoveries all the time. Previously, researchers have explored the role of inflammation and oxidative stress as contributing factors.
More recent research looks at intestinal permeability (leaky gut) and your gut microbiota plus the possible pathways through which these can influence your brain and your behaviour via the gut-brain axis. These more recent discoveries carry the added positive of having an impact quickly.
Considering our desire for instant gratification, it is sometimes difficult to “sell” health messages that will benefit someone in the future — perhaps by improving cardiovascular health in older age or helping to prevent bowel cancer, for example. These changes, increasing fibre in the form of a variety of vegetables, fruit, legumes, wholegrains, nuts and seeds, can change your gut microbiome within a week. Now that is rapid!
Likewise, our microbiota can be negatively affected by eating ultra-processed foods in just as tight a timeframe, therefore negatively impacting your mood. Eating plenty of complex carbohydrates (wholegrains) and plant-based foods, vegetables and fruit has an enormously positive effect on your gut microbes, enabling and encouraging them to become stronger, to make more of their own magical by-products which exert anti-inflammatory effects and improve the health of your entire body and mind.
A nutritional perspective
You might also look at this from a nutrient perspective, nourishing yourself with the particular nutritional factors that support your nervous system and mental health. B vitamins, vitamin C, vitamin D, magnesium, iron, calcium, zinc and omega-3 fatty acids work together in critical roles such as manufacturing key neurotransmitters, dealing with stress and its effects, enabling proper communication of neurological messages and producing a calming effect on the body, and are absolutely essential for healthy brain function. No one food will be able to consistently deliver the quantities of these nutrients required to balance your nervous system, so eating a variety of whole foods gives you the best chance of benefiting from their nutrition.
I don’t believe supplementation with these nutrients is always the answer, either. You assimilate a supplement differently from food and every individual will have a varied ability to absorb them depending on their background, health history, the state of their digestive system and vitality in general. Supplements will also neglect to give us that crucial fibre element.
There are certainly times when supplements are indicated; however, for general health, stress protection and nervous system nourishment, eating well as mentioned above will naturally deliver these nutrients to your body in a form that it can best understand and absorb.
So, which food contains the necessary nutrients to help your brain and body to relax? In essence, you need a variety of all colourful, fibre-rich foods as well as keeping ultra-processed and refined foods to a minimum. This is great news for those of us who love our vegies. Singling out any one in particular is a little like choosing which child is your favourite; however, there are a couple of standouts you might be interested in.
Food stars
Fermented foods have been shown to improve cognitive function and reduce stress via neuroprotection, enhancement of function and anti-inflammatory activity. The process of fermentation also seems to improve the bioavailability of food, amplifying the benefits and improving digestibility. The hypothalamic-pituitary-adrenal (HPA) axis is involved in the body’s stress response. Gut microbiota are significantly linked with the HPA axis in that they can reduce an exaggerated HPA axis response (a stress response) and fermented foods have been shown to enhance this process.
There are many different forms in which you might like to try this hard-working functional food. Sauerkraut, kimchi, kefir and kombucha are fairly readily available at health food shops, markets and even some supermarkets. Look out for local brands that have not been irradiated or pasteurised so that you can enjoy the full benefits. Don’t forget about the other ferments available to you such as miso, tempeh or the endless possibilities that you could also make yourself.
The second standout is fibre. It’s crucial to your gut microbiota, which ferment it to positively influence their own balance and your health, and the effects will reach beyond stress management to complete wellbeing. Nature has provided us with so many delicious ways to enjoy this essential element — many mentioned already above — and it is an extremely achievable goal to get plenty of fibre into your diet in delicious ways.
Try including fibre in each meal if you can and see what a difference it makes. Perhaps it is porridge for breakfast, or an omelette with veg. I’m a big fan of hummus atop some gorgeous, wholegrain sourdough. Maybe it’s swapping your white grains for the wholegrain version or it could be keeping plenty of chickpeas and lentils on hand to throw into soups, stews, stir-fries or curries. Go for around 50 grams of fibre a day and variety of fibre is the key.
Here are some recipes to help you build these nerve-nourishing foods into your daily diet in delicious ways.
Pea, Sunflower and Miso Dip
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Black Bean Salad with Jalapeno and Lime Dressing
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