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Gut Health and Depression

Updated: Oct 15, 2021


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:

  • 5 to 9 servings of vegetables per day. Large quantities are consumed, with a lot of leafy greens.

  • Fruit is consumed several times a day, commonly grapes, tomatoes, figs, melons, and cucumbers.

  • Grains are serve daily at each meal, mostly wholegrain and in moderate portions.

  • Fish is eating 2 to 3 times per week.

  • About 4 to 5 tablespoons of extra virgin olive oil per day, preferably raw.

  • Make sure fat is mostly from unsaturated sources (good fats).

  • The Mediterranean diet provides around 33 grams of fibre per day (lots of plant food).

  • Red wine is consumed daily but always with meals and in moderation.

  • Snack on a handful of nuts.

  • Poultry is consumed in small amounts and red meat less often.


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.




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