At first glance, it may seem unlikely that your diet would affect your mental health, and yet it is not that far-fetched if you think about it on a chemical level. Our brain needs chemicals (i.e. nutrients) for structural as well as functional purposes and where would those chemicals come from, if not from our diet, or of course, medication. While the appropriate drug may be helpful, your diet should be the first port of call. The most common mental health issues of our time are depression and anxiety. Now, during the lockdown, these are likely to affect even more people than usual.

1. Balance Blood Sugar

We have written about this before but will again, because balanced blood sugar levels are the cornerstone of good health, including brain health and mood. Our body does not allow our blood sugar levels much leeway. At any given time, there should be around 5g of glucose travelling around our system. Too much is just as dangerous as too little, which is why hormones tightly control our blood sugar level (more accurately the blood glucose level). Insulin brings it down, glucagon and cortisol raise it. You can see right there, how glucose interferes with hormones.

The blood glucose level changes every time we eat, but what, when and how often we eat affects how fast and how high it will go. What we are aiming for is a gently undulating wave, not spikes and troughs. The more sugar, the more refined carbohydrates a meal contains, the faster and higher blood sugar will rise. Although the brain uses a lot of glucose for energy, brain cells do not like being bathed in it. Any surplus has the potential to do damage by literally sugar-coating cells. It is for this reason that insulin kicks in to remove any excess sugar, but constantly elevated insulin levels come with their own problems. If cells are exposed to too much insulin all the time, they can become resistant to it, which sets us on the path of diabetes. Moreover, both sugar and insulin are independently inflammatory. In this way, what you eat (or don’t eat) contributes to systemic inflammation, which has been described as a major cause and consequence of depression.

The overconsumption of sugar and refined carbohydrates may also upset the composition of the microflora in our gut. Gut bacteria are now known to affect our mood and behaviour via the gut-brain axis. More on that below.

Read here for our top tips for balancing blood sugar (covered in more depth in our webinar How to Have Great Energy All Day).

Getting blood sugar levels under control is the first and most important step towards a better and more stable mood, more energy and better sleep. However, there is more that you can do with food to support your mental health.

2. Embrace Good Fats

After decades of listening to nutritional advice that emphasised low-fat diets, many people are reluctant to let fat back into their life. Yet, there is no doubt that we do need fats for many bodily functions, not least for the brain and nervous system.

The human brain consists of almost 60 per cent fat. The long-chain omega-3 fatty acid DHA is one of the main components of the brain and is indispensable for the health of the human brain. Beyond their important role in building the brain structure, essential fats are involved as messengers in the synthesis and functions of brain neurotransmitters.

We have already mentioned the involvement of inflammation in depression. Certain fats – the essential fatty acids omega-3 and omega-6 have anti-inflammatory properties. Both omega-6 and omega-3 fats are further converted substances (called eicosanoids), which in the case of omega-6 can be pro-inflammatory or anti-inflammatory, while eicosanoids from omega-3 fats can only be anti-inflammatory.

In nutrition, “essential” always means that the substance has to come from the diet. The body cannot produce it itself. Both omega-6 and omega-3 fats are essential, and the balance between them should be 1:1 to 4:1. In the typical Western diet, however, ratios of up to 30:1 are not unheard of. It is not difficult to get sufficient omega-6, much harder to get the appropriate omega-3.

While the body can make the long-chain fatty acids it needs – EPA and DHA – from plant-sourced omega-3 as found in flaxseed, walnuts and pumpkin seeds, conversion is poor and can easily be further disrupted, for example through illness and inflammation or stress. The best plant source of DHA is seaweed, but of course, it doesn’t contain a lot of fat. Eating it to top up DHA levels would be difficult, but vegan DHA supplements are available.

The best food sources of EPA and DHA are animal foods: omega-3 eggs (which are higher in omega-3 than regular eggs, because the hens are fed omega-3-rich seeds), grass-fed beef and – the best source of all – fish and seafood, particularly oily fish such as tuna, salmon, mackerel, herring, sardines, pilchards and anchovies.

For more on omega-3 fats, check out our Guide to Omega-3 Fats published earlier this month.

3. Happy Gut Flora – Happy You

The gut flora (i.e. the microbiota) is emerging as a possible key player in the regulation of mood, cognition, and anxiety. We are only beginning to discover the potential of food as medicine. Dietary fibre is a prebiotic and its consumption can alter the composition of the microbiota – even within a few days.

“Prebiotic” is what we call the feed of gut bacteria (as opposed to “probiotic”, which are the actual live bacteria themselves). New technology has allowed scientists to delve much deeper into the world of microbes than was possible before and there is still very much research to be done. It has become clear, however, that high diversity of gut bacteria is a good thing. In the gut at least we want as many different species as possible. Because different species thrive on different foods, this is best achieved by having a highly varied diet.

Prebiotic food means food rich in fibre. As our body cannot break down fibre, it was long thought to be roughage that has no function for us. Not so! We may not be able to digest it, but the bacteria in our colon can. They are able to extract further nutrients, including B vitamins, vitamin K and short-chain fatty acids for us – the latter in particular are another crucial nutrient for good mental health.

Eating a diverse diet is another key factor in building a healthy range of bacteria in the gut – aim for at least 50 different plant foods across the course of a week (keeping a chart of each new food is a fun thing to do with children during lockdown).

4. Dare to be old-fashioned

In 2017, a group of research scientists published the first “Dietary recommendations for the prevention of depression”. In it they recommend following “traditional” dietary patterns, such as the Mediterranean, Norwegian, or Japanese diet. Those three were singled out, because the researchers could refer to relevant research from those countries. It is highly likely that any traditional diet, from anywhere in the world, would achieve similar results, because the scientists go on to recommend:

increase consumption of fruits, vegetables, pulses, wholegrain cereals, nuts, and seeds;
include lots of foods rich in omega-3 polyunsaturated fatty acids;
replace unhealthy foods with wholesome, nutritious foods;
limit your intake of processed foods, junk foods, bakery goods, and sweets.

What emerges is a diet of real food. Traditional diets do not contain processed foods, junk food, sweets, or damaging transfats and vegetable oils. Traditional diets – no matter where – rely on real food only: meat, fish, eggs, dairy, fruit, veg, nuts, seeds, pulses, grains, herbs, spices. Those are ingredients for meals, not meals. Granted, not every traditional diet contains high amounts of oily fish as many areas are landlocked, but before factory-farming and chemical agriculture, their meat, dairy and eggs would have been naturally higher in omega-3 and lower in omega-6 fats.

You don’t have to go back to an old-fashioned diet of offal (though that would be very nutritious), potatoes and overcooked cabbage. However, for your mood, your brain and your mental health, it really is worth switching back to home-cooked meals made from real food.

For more on this topic, read our Mood Food article published in 2018, or why not book our Eating for Mental Wellness Webinar? Call 07966 478974 or email

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