HOW COULD YOUR DIET BE AFFECTING YOUR MIND? FOOD FOR THOUGHT

HOW COULD YOUR DIET BE AFFECTING YOUR MIND? FOOD FOR THOUGHTHow could your diet be affecting your mind? Food for thoughtWhether you’re feeling on top of the world or a little below par, you may be unaware that yesterday’s lunch could be influencing your mood today. What we eat can affect our minds, emotions and mental health. Scientists are increasingly referring to the human gut as the ‘second brain’ as they uncover connections between food and our mood.Bacteria and the brainThere are trillions of bacteria that live in our guts, which can affect our brains. What we eat changes the living conditions of these microscopic inhabitants. The variations that occur in their environment mean that different types of bacteria thrive depending on our diet. Whilst some bacteria might enjoy pizza, others may prefer salad. This means that the composition of bacteria in our guts is individual and ever changing. But why does this affect our minds?Some species of bacteria produce chemical signals that can travel from our guts up to our brains. These signals are called neurotransmitters. Our brains also produce versions of these, causing us to experience emotions. One neurotransmitter that you’re likely to have heard of is serotonin; when your brain produces a lot of this, it makes you feel happy. You might be interested to learn that 90% of the serotonin in our body is actually found in the gut and that our bacteria have a lot to do with this. They help with its production and that of various other neurotransmitters, meaning they have some control over our emotions. A scary thought!CravingsThis microbial mind control has also been shown to influence cravings. We know that some bacteria prefer it when we eat particular foods. Encouraging us to eat these foods benefits their growth, allowing them to become more dominant in our gut’s bacterial population. Growing in numbers increases their influence on our brains, so the craving intensifies. This could lead to an endless spiral when you give into those chocolate cravings. When comparing people who crave chocolate with those who don’t, it has been shown that their gut bacteria are different. This has been seen in studies looking at the differences in the bacterial by-products found in people’s urine. It has also been demonstrated that eating chocolate can stimulate the growth of certain groups of bacteria. Perhaps these are the culprits that manipulate our neurotransmitters, causing us to have a feeling of relief and comfort after satisfying a chocolate craving. As well as chocolate-loving bacteria, an interesting study in 2010 found that there is a species of bacteria (Bacteroides plebeius) that particularly likes seaweed. It has the ability to digest a seaweed-specific carbohydrate. Bacteria with this particular skill are found in abundance in the sea, and the only other place in the world that they have been located is in the guts of Japanese people. They could give rise to cravings, which might explain the estimated 9 billion pieces of seaweed eaten every year in Japan.Our bacteria can also trick us into thinking that we’re hungry or full. Some of them can change the levels of hormones, for example, ghrelin, that tell us if there’s room for more food. Ghrelin is the ‘hunger hormone’ and causes an increase in our appetite. One type of bacteria that may alter the levels of ghrelin is Helicobacter pylori. Some experts have identified that in the past there were more of these bacteria living in the human gut. This has been suggested as a possible contributing factor to the recent rise in obesity.A common means by which scientists look into the effects of gut bacteria is through using germ-free mice. These are mice that are born and live in completely sterile conditions, so they have no bacteria at all. An interesting study in 2012 found that germ-free mice crave sweet things and have more sugar taste receptors than normal mice.Mental healthScientists are making links between the composition of bacteria in people’s guts and certain mental health disorders. It is often thought that having poor mental health causes people to eat unhealthy comfort foods, but this is a two way street. Eating poorly may increase the amount of particular bacteria associated with depression, anxiety and other illnesses. In recent years, the importance of gut bacteria in mental health has become increasingly evident. In one experiment, scientists fed mice a strain of helpful bacteria called Lactobacillus rhamnosus and noticed these mice had a completely different attitude compared with normal mice. They seemed a lot braver and more confident. Additionally, germ-free mice were notably more anxious until they were exposed to bacteria.Further experiments in mice have shown that they exhibit anxiety or depression-like behaviour when certain bacterial populations become too large in their guts. Depressive states in people may be partially due to neurotransmitters or other chemicals released from certain members of our bacterial population. Depression is an extremely common illness that affects 1 in 5 people at some point in their lives. Maintaining a good composition of bacterial species in our guts could help reduce our likelihood of suffering with depressive symptoms.Targeting our gut bacteria may prove to be an interesting avenue for treatment of certain mental health disorders in the future. There is research being done into the use of psychobiotics. With these, people would be prescribed certain types of bacteria to improve the symptoms of mental illness. The psycobiotic, ‘good bacteria’, will be taken so that they can out-compete and reduce numbers of the species contributing to poor mental health or negative emotions. One interesting study showed that even eating probiotic yoghurt increased the happiness of people who described themselves as depressed in the first instance.In addition to psychobiotics, manipulating our gut bacterial composition can be done through faecal transplants. Transferring a sample of the contents of somebody’s gut, including the bacteria, into someone else’s gut has been shown to treat certain conditions. This may be an avenue for future treatments of mental health disorders such as anxiety and depression.Scientists think there may also be a link between gut bacteria and autism. It has been found that the internal bacterial signature is different in children with autism compared to those without. Indeed, lacking particular species in their guts is being increasingly linked with the disorder. Performing faecal transplants in mice has been successful in reducing autism-like traits. Although this is in the early stages, it may prove an interesting avenue for the development of future therapies for those with autism.Becoming happier through your dietThe ratios of different bacterial types in your gut can change after just one meal. Eating the types of food that increase populations of good bacteria (and therefore reduce the amount of bad bacteria) can cause improvements in our mood and mental health. So how can we change our diets to keep our bacteria, and consequently ourselves, happy? Here are some possible changes that you could make:

Probiotics
Probiotics are live bacteria, of the good kind, that you can eat to keep the balance in your gut healthy and your brain happy. Psychobiotics are a version of these bacteria that specifically aim to improve mental wellbeing. Probiotics can be found in certain foods or supplements. Studies have shown that when mice have probiotics, their levels of a stress hormone called cortisol drop. There are also studies that have shown the links between the consumption of probiotics and reduced depression. Yogurt is the first probiotic-rich food that comes to mind but there are other fermented products, such as sauerkraut and pickles, which contain healthy live bacteria as well.

Prebiotics
Prebiotics provide an optimal gut environment for bacteria to grow in. Eating these foods sets up your gut to host the best types of bacteria, by providing them with the nutrients that they need. Foods called fructans are good prebiotics. They are made up of many fructose molecules and examples include bananas, garlic, onions, artichokes and wheat. Legumes, for example, peas, beans, lentils, chickpeas and peanuts, are also great prebiotics.

Foods low in saturated fats and sugar
A diet with low levels of saturated fats and sugars is much better at promoting the growth of the good bacteria in our gut and preventing the bad ones from taking over, producing neurotoxins and negatively effecting your mind. Keeping these food types to a minimum could help reduce tiredness, headaches and moodiness, and improve memory and concentration.

Complex carbohydrates
Some of the bacteria in our guts have a special ability to digest complex carbohydrates such as fibre and resistant starch. This is useful because we don’t have the right enzymes to break them up ourselves. This mutualism aids our digestion and provides the bacteria with energy, allowing them to increase in number and outcompete the bad species. Good sources of resistant starch are wholegrain products and bananas that are not quite ripe yet, these are excellent prebiotics as well.

A varied diet that is packed with nutrients
Eating a diverse diet keeps your internal environment changing therefore stopping it favouring the growth of only one bacterial type. Furthermore, after people increase the nutrient density in their diets, they find their cravings begin to wane. This could be due to the reduction in those bacteria that can manipulate you into fancying a certain food or increasing your hunger level.

Only take antibiotics when necessary
This is not really a diet alteration but, as well as being hugely beneficial, antibiotics can be really damaging to your internal population of bacteria. Often, antibiotics are not very specific and end up killing off quite a large proportion of good bacteria as well as the ones causing the infection. There are many reasons why you should only take antibiotics when your doctor tells you to, including the potential effects on your mind.

The study of how our gut bacteria affect our minds is a growing field, with more and more evidence coming to light supporting this phenomenon. Studies have indicated the importance of these microbes in influencing our moods, cravings and even mental health. Treating our ‘second brain’ well through good dietary choices might mean happiness in the first one too. Next time you have a gut feeling about something you may be experiencing bacterial mind control!By Antonella Russell