 Photo by Ella Olsson It’s amazing how much research is emerging about gut health lately. Nearly everyday there’s a new study showing the links between the human microbiome and a specific disease or condition. We are heading in the direction of individualised nutritional treatments that shift gut bacteria in a certain direction to improve health. So exciting!
Food has magical powers to change your gut bacteria. Okay, not magical; pretty scientific really, and pretty damn fast if you choose. As fast as a few days with a drastic diet change, for better or, unfortunately, for worse. Foods high in sugar are particularly bad for our gut bacteria. However, eating a lot of processed and packaged foods, and red meat in general, will not support the growth of beneficial bacteria in your gut. Of course, the best diet to support the growth of healthy bacteria is one with A LOT of vegetables. This is where you’ll get that lovely stuff called fibre and resistant starch. These nutrients provide food (prebiotics) for your microbiome; also gas, but that’s ok. Some fruits, legumes, nuts and grains also provide food for your gut bacteria. Some of the best “prebiotic” foods to focus on include:
What is Fibre? Dietary fibre is basically the edible parts of plants that are resistant to digestion and absorption. Fibre partially or completely ferments in the large intestine, providing food for beneficial bacteria. Dietary fibre plays many roles besides supporting gut bacteria, it also,
Food Labels and a Healthy Gut When reading food labels, you want to avoid products that are high in sugar, contain additives and low in fibre. If you’re looking for products to feed your gut bacteria, fibre is the first thing to check. We should consume 25 to 30 grams of fibre per day. Most Australian’s do not get anywhere near this amount. Although it’s always best to get the majority of your nutrients from wholefoods, there’s nothing wrong with choosing a high fibre cereal to support your gut health. However, be very aware of the sugar content as well. First of all, check the ‘Nutritional Information’ panel. Don’t worry too much about the ‘Per serve’ column unless you are sure that this is exactly how much you will serve yourself (often it’s not). The ‘Per 100g’ is where you should look; this column should also be used when comparing products because different products will have different measurements for their serving sizes. Under ‘Carbohydrate’ there will be ‘sugar’. A low sugar product will have 5g or less per 100g. Anything above 10g per 100g is considered a high sugar product. If the product contains fruit, the 'sugar' amount will also include natural sugars that come from fruit. If this is the case, have a look at the ingredients to get an idea of how much “processed sugar” it contains. IBS and Prebiotic Foods People who have medically diagnosed IBS often find high fibre foods aggravate their symptoms. As a result, this information may not apply at the moment. The ‘Monash University low FODMAP diet’ has shown to be an effective treatment for IBS. You should only take on this diet under supervision of a dietitian. It is recommended that this diet is followed for 2 to 6 weeks and then your dietitian will advise you on re-introducing foods slowly. The long-term goal of FODMAP is to return to a normal diet as much as possible. Avoiding “prebiotic foods” long term will impact the growth of certain bacteria in the gut.
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 A few days ago, I came across a study which linked two specific beneficial bacteria strains to depression. The study found that those who had been diagnosed with depression had consistently low levels of these strains of bacteria. Now I can’t for the life of me find this damn article again, and I have forgotten the names of these two bacteria strains. One started with ‘C’ and one started with ‘D’. Yeah helpful, I know, but I'll tell you what I learnt from what I read. I guess, knowing the names isn’t really important, but understanding how to encourage the growth of these beneficial bacteria is what we really want to know. Further research into the strain that starts with ‘C’ lead me to omega 3. This surprised me. I’ve always associated foods that encourage the grown of good bacteria to be plant based, you know, to provide the little guys with fibre and resistant starch (prebiotics). So, a fatty acid was something different and I had to know more. One of these beneficial bacterial strains was also shown to be a pathway for dopamine, an important neurotransmitter that plays a role in mood by creating positive feelings of reward and increasing motivation. People with depression often show low motivation and a decrease in pleasure; both which are linked with dopamine. I also came across a few other studies which showed that omega 3 fatty acid supplementation significantly increased the diversity of a handful of beneficial bacteria. Including at least one associated with depression. There’s a whole heap of information out there about prebiotic dietary fibre and it’s beneficial effects on our gut microbiome. However, the impact that dietary fats (like omega 3) has on the human microbiome is not covered much, just yet. So far, studies are showing some positive effects using omega 3 supplementation, but that makes me wonder about the effects of a healthy diet? Oily fish, olive oil? One study looked at the effects of supplementing with omega 3 compared to the well-known prebiotic fibre ‘inulin’. Although both resulted in an increase of beneficial bacteria, each supported the grow of different types of bacteria. So, in other words, one isn’t better than the other. But one will give you different results compared to the other. Therefore, eating a wide range of foods is the best method to take. Watch Out for Fad Diets Singling out nutrients (while this may bring on some temporary positive results), will reduce your microbiome diversity. Look at one of the healthiest diets in the world, the Mediterranean diet. They consume such a huge variety of everything, including vegetables, fruits, nuts, fish, bread, wholegrains, olive oil and wine. They have a major focus on plant foods, but their diet is balanced, varied and abundant. Olive oil and oily fish is consumed regularly in the Mediterranean diet, both which are good sources of omega 3. Unfortunately, when we start cutting out food groups, commonly a result of fad diets such as paleo, keto, low carb, fasting diets and gluten free, we deprive ourselves of what our body needs! Variety. You can’t get all of the nutrients you need from only one of two food groups. You need them all in moderation (if possible). I better add that I only included gluten free for those who take on this diet when they don’t need to. If you are gluten intolerant, coeliac or have an allergy, then it’s absolutely necessary to be gluten free. I was gluten intolerant (non-coeliac) for about ten years, it sucked. But now that I have recovered, I LOVE gluten and I am much healthier with it. Pass the bread. That experience taught me about how cutting out an entire food group (even though it was necessary at the time), can actually be detrimental to your health. The Benefits of the Mediterranean Diet The Mediterranean diet is an inspiration to me. It’s not really a diet, but rather a lifestyle that draws its inspiration from southern European countries. They understand moderation and variety. They have an emphasis on plant foods, grains, beans, olive oil, fish and poultry. All which supports a healthy gut. Although they do eat red meat, it’s more of a “treat” food, and served only a few times a month in small amounts. Red meat is not good for our microbiome in large quantities, and the Western diet encourages a lot of red meat, unfortunately. Studies show that those who follow a Mediterranean diet have a lower risk of many diseases, including diabetes, cancer, cardiovascular disease and obesity. However, you may notice that included on the Mediterranean Diet Pyramid (see below), is physical activity and socialisation. So, this is more of a lifestyle than just a diet. There are several studies showing that the Mediterranean diet reduces the risk of depression and is an effective treatment for depressive symptoms. This is most likely due to the amazing gut health benefits (gut-brain connection), as well as the countless other nutritional benefits this style of eating will provide. Stress is another factor that impacts our gut health. I don’t know what the stress levels are like in these counties that follow the Mediterranean diet, but I have a feeling it’s less than we have in Western countries. I’ll save that for another article, or I’ll never shut up. Anywho, if you’re interested in taking up ‘Mediterranean-style eating’, the good news is, it’s not difficult. There is no single definition of a Mediterranean diet, but based on some research I found, here are some loose rules:
Update, 5th January 2021 - Although this isn't the same article I read originally. This article is about the same study which mentions the names of the bacteria.   There are not many studies currently available on the Mediterranean diet and its effects on mental health; however, there is some evidence which shows that the nutrients gained from this diet, such as antioxidants, omega 3 fatty acids, fibre and B-vitamins positively effect mood and brain function.
What is missing from many studies is the impact that the Mediterranean lifestyle also has on mental health, which includes diet, lifestyle, social and cultural aspects. Although diet does play a part in treating mental illness, it is not the only aspect which should be considered. Dietary Strategy What a person eats directly affects functioning of the brain, and as a result, a person’s mood. The brain can only function at it optimal levels when a good diet rich in antioxidants, vitamins and minerals is consumed. A poor diet that is high in refined food has been shown in multiple studies to affect brain function and increase symptoms of disorders such as depression. The Mediterranean diet is associated with reducing the risks of many chronic diseases, however there is currently limited research on the affects it has on mental health. Many components of the Mediterranean diet encourage healthy brain function such as omega 3 fatty acids, antioxidants and B vitamins. As well as this, the Mediterranean diet is rich in vitamins, minerals, polyunsaturated fatty acids and antioxidants which have been shown to have a positive impact on mental health. How Diet Affects Mood The gastrointestinal tract is lined with millions of nerve cells, making it more than just a place to digest food, but also a mood regulator. Around 95% of serotonin is produced in the gastrointestinal tract. The production of serotonin and the functioning of the neurons in the gastrointestinal tract are highly influenced by the intestinal microbiome which are directly affected by diet. Studies have shown that traditional diets such as the Mediterranean diet, can lower the risk of depression by 25% to 35% when compared to a Western diet. This is due to the abundance of vegetables, fruits, whole grains and seafood in traditional diets such as the Mediterranean diet, as well as the limited amounts of red meat and dairy consumed. Recently more evidence has shown that there is a link between diet and mental health. Studies have shown that consuming a healthy diet rich in vegetables, fruits, olive oil, nuts, legumes and fish can provide protection against depressive symptoms. However, a diet high in sugar and processed foods is seen to have a negative impact on mental health, particularly depression. The Mediterranean diet provides an abundance of fruits, vegetables, whole grains, nuts, legumes and fish. These foods are rich in antioxidants, fibre and many other nutrients that are positively associated with mental health. The Mediterranean diet provides a much higher proportion of omega 3 fatty acids compare to the high consumption of omega 6 fatty acids seen in a typical Western diet. Research has shown the importance of omega 3 fatty acid in supporting good mental health. The key concepts of the Mediterranean diet and its effect on mental health are due to the diet being rich in a variety of nutrients which are associated with positive mental health effects. The Mediterranean diet is rich in antioxidants, omega 3 fatty acids, and B vitamins which are shown to positively affect mental health and brain function. The Mediterranean Lifestyle The existing theories indicate that the Mediterranean diet and its effects on mental health isn’t just about what food is consumed. It’s also about the lifestyle. The Mediterranean lifestyle is a holistic approach to supporting mental health. Although the diet provides a rich source of nutrients which are shown to positively affect mental health and brain function, the Mediterranean lifestyle also plays an important role. This include the social aspects and physical activity. The benefits of a meal go far beyond the nutritional aspects in the Mediterranean culture. The social benefits of leisure time, cooking, sharing, and eating together in positive company support good mental health which are all depicted in the Mediterranean diet pyramid as essential aspects. Another important component of the Mediterranean lifestyle is leisure time which provides a social aspect beneficial for mental health. More studies need to be done which include a whole lifestyle approach. A lack of social connectiveness can contribute to poor mental health including depression. However positive social connections can reduce the risk of poor mental health. The Mediterranean lifestyle has a very important social aspect which supports overall wellness. The Mediterranean diet pyramid provides a holistic representation of a healthy lifestyle which benefits mental health including not only diet but also the cultural, social and physical aspects of good health. Looking at a single aspect such as diet does provide some benefits, however taking a holistic approach provides more long term positive effects for mental health as well as overall wellbeing. Take home messages:
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