Not only is the gut, which is teeming with over two kilos of a huge variety of bacteria, responsible for digestion, it also has an influence on brain function and is an important part of our immune system. The interaction between the stomach and the head is effected via the so-called gut-brain axis and is bidirectional. The neurologist, Professor Dr. med. Aiden Haghikia, speaks about this interaction, and about how and which components of our diet have an impact on the brain and what happens when our microbiome falls out of balance in this podcast.

Todays Guest

Professor Dr. med. Aiden Haghikia is the Director of the University Department of Neurology in Magdeburg. Together with his team, the neurologist is researching the influence of diet and the gut microbiome on the human brain, and more precisely on the mechanisms that lead to the death of nerve cells in the brain in chronic inflammatory and neurodegenerative diseases such as Multiple Sclerosis (MS) and Parkinson’s. Their objective is to develop new treatments.

*the audio file is only available in German

The Podcast to read

Intro voiceover: Learn when you want to. The podcast about research at the University of Magdeburg.

Friederike Süssig-Jeschor: You are what you eat. This is not just a saying. The human gut is teeming with trillions of microorganisms. Nowadays we know that the gut does much more than simply process food. It is the center of our immune system, and the multitude of microbes also play a part in the development, function and health of our brain.

The topic of conversation with our guest today is this interaction, the influence of diet on the brain and what happens when our microbiome goes out of kilter. Prof. Dr. med. Aiden Haghikia! Professor Haghikia heads the University’s Department of Neurology in Magdeburg and his research deals with the gut-brain axis and its impact on the emergence of what are known as neurodegenerative diseases.

My name is Friederike Süssig-Jeschor, I am the press officer in the Faculty of Medicine at the University of Magdeburg. Professor Haghikia, I am delighted that you are here today. Welcome!

Prof. Dr. med. Aiden Haghikia: Thank you very much for the invitation.

Friederike Süssig-Jeschor: To begin with, I’m going to reveal to you that this morning I had a big bowl of muesli for breakfast! And I would like to know, what did you have?

Prof. Dr. med. Aiden Haghikia: A cup of coffee and a glass of water for me.

Friederike Süssig-Jeschor: Oh, well that’s very straightforward! Don’t you eat breakfast?

Prof. Dr. med. Aiden Haghikia: When I drive to work it’s quite early. And it’s a little bit too early for me to eat breakfast. So I eat my first meal, an apple or a banana, at about 10 o’clock.

Friederike Süssig-Jeschor: Aha. Now, of course, I’d be really interested to know which of us is making the better choice in terms of our brain health, but first things first. Professor Haghikia, you have been carrying out research into neurodegenerative diseases such as Parkinson’s and Multiple Sclerosis for over 15 years. Can you explain to our listeners what exactly that entails?

Prof. Dr. med. Aiden Haghikia: The term “neurodegeneration” means the death of brain cells. That is, of the neurons, the nerve cells. It can affect certain parts of the brain, but can also affect entire systems, in other words, everywhere - indeed we all have a degree of brain shrinkage - as we age. Usually it is compensated for by other mechanisms, it is offset by other processes. Our brain is very plastic, it can relearn a lot of things - if these mechanisms are no longer effective. And when that cell death begins to prevail, only then does a disease occur that as neurologists we are able to identify and potentially treat.

Friederike Süssig-Jeschor: And specifically these two diseases? What is, for example, the difference between MS and Parkinson’s?

Prof. Dr. med. Aiden Haghikia: Multiple sclerosis and Parkinson’s disease have a commonality, in that in the final pathway of the disease, cell death, nerve cell death, occurs. The causes, the triggers, are very different. With MS, we know the triggers, which are outside of the brain. It is the immune system or the inflammatory cells. The initial trigger comes from the immune system in the context of an autoimmune disease, which attacks the nerve cells and their nerve sheaths in the brain. It is different in the case of Parkinson’s disease. Here, we have not yet determined the triggers and causes. For a long time we suspected that they lay in the brain, but now know that that is not the case.

Friederike Süssig-Jeschor: Expressed again in figures for all of our listeners: an estimated 500,000 people suffer from Parkinson’s disease and another 240,000 people are living with MS in Germany. In the case of MS alone, the number of sufferers has doubled in the last 40 years, and the trend is increasing. And many are also becoming ill at a younger age. You have already mentioned it briefly - what do we already know about the causes of these diseases and how, above all, can this development be explained?

Prof. Dr. med. Aiden Haghikia: In the case of MS, there are two reasons why it is increasing. One is that we are able to identify MS much earlier and more quickly. However, we are seeing a trend with all autoimmune diseases, such as with rheumatoid arthritis, psoriasis, and also diabetes mellitus, that these diseases are increasing in prevalence. We do not fully understand why that is the case. We have a number of hunches.

I’ll come to it afterwards - with diet and the gut, the changes that we are currently experiencing. In the case of Parkinson’s, the disease has long been seen as a disease of older people. And since society as a whole is becoming older, such diseases naturally occur more frequently.

Friederike Süssig-Jeschor: You have already mentioned that for a long time it was suspected that the causes lay primarily in the brain, specifically in the case of Parkinson's disease, but that that turned out to be a dead end. So, bearing in mind the numbers of people affected, which are indeed very high, did we, so to speak, spend too long backing the wrong horse? And waste important scientific resources as a result?

Prof. Dr. med. Aiden Haghikia: You can never say that exactly. We learned a great deal from this research. We learn lessons from negative results too, knowledge that this path no longer needs to be followed, that, so to speak, it is the wrong horse, as you put it. But science is a cumulative endeavor, that is natural science and also human sciences.

From all of these findings, we have learned that there is no such thing as Parkinson’s disease. What I mean is that there is a multitude of different disorders that result in the same clinical picture. We have genetic forms of Parkinson’s, which are definitely rarer. We have secondary forms of Parkinson’s, in other words, reduced blood flow, infections in the brain, such things can cause Parkinson’s. The classic Parkinson’s has many different faces and, in my opinion, probably also many different triggers.

We have - as you just mentioned - recently learned from a study that was published just a couple of weeks ago, that it is not enough to break up the misfolded proteins. The key protein here being Alpha-synuclein. For a long time this was suspected of being the trigger. When we break it up, which we can with this antibody treatment, however, it does not lead to the disease being arrested or to any improvement.

Friederike Süssig-Jeschor: In your research you are focusing on a particular or certain component, that is, the influence of diet on this disease, and are looking in the process at a certain component of our diet. Which is that?

Prof. Dr. med. Aiden Haghikia: The component, to keep it brief, is short-chain fatty acids - so fatty acids, the fat from our diets, a mixture of different fatty acids. We are looking at fatty acids and what impact they have. For one thing on the local environment, that is on the gut wall and the nerve cells located there and the immune cells. We often forget that our gut is the biggest nervous and immune system outside of the brain.

And these cells, above all the immune cells, they don’t just sit there, instead they are highly dynamic, they move around, they are able to leave the gut wall and can, among other things, also reach the brain and cause damage there, as is the case with MS. With Parkinson’s disease it is the case that the disease is an ascending disease. We have symptoms that above all affect the autonomic nervous system, among other things the gastrointestinal tract. This means, that the gut and the motility of the gut. but also the ability to smell and this development occurs bottom-up. In other words, it can take years, decades, for movement disorders to happen, and here too, we suspect that the link is between the gut and the brain, that is, the so-called gut-brain axis.

Friederike Süssig-Jeschor: And why, exactly, fatty acids? Does it have something to do with our eating habits?

Prof. Dr. med. Aiden Haghikia: For one thing, the first observations date back almost 100 years from which we know that, in the context of MS, but also other autoimmune diseases, that dietary fat can pose a risk. What we know as fat, or in general understand as fat, is the substance that we use for frying. That is, the thing that is contained in butter. We often forget that plant cell walls also contain fatty acids.

That is, they are packaged in very large molecules. But first of all they have to be decoded. These are short-chain fatty acids, which have a completely different role in the body, but also have a different effect on the inflammatory reaction and on nerve cell death.

Friederike Süssig-Jeschor: What exactly have you been able to discover through your research?

Prof. Dr. med. Aiden Haghikia: We were able to show that both in the case of MS patients and Parkinson’s sufferers, the short-chain fatty acids, and above all the propionic acids... ...there are several kinds of fatty acid - there is also butyric acid and acetic acid - that they are reduced. This means that we have a kind of deficiency, that previously we were unaware of. It does not have something to do with these people eating differently, but rather how nutrients are broken down in their bodies.

In other words, whether we are in a position, for example with the bacteria, above all with the bacteria that we have in our guts, to split these complicated sugar molecules in the cell walls of the plant cells, so that the substances can be released and then absorbed by the body. We were able, firstly, to show that the short-chain fatty acids, and in particular, in MS, propionic acid, lead to more regulation cells being produced.

These are control cells that prevent incorrectly programmed immune cells from attacking our own bodies. They are weakened and also clearly reduced in numbers in MS. And we could reverse this by supplementing these short-chain fatty acids. This means we could get past this deficiency, get past this altered microbiome, we could enrich it and achieve the opposite effect.

We have also seen that the short-chain fatty acids, they are in a position, initially in cell culture, but now also in people with Parkinson’s disease, with the Parkinson-type disorders... that there is a certain protective mechanism. These short-chain fatty acids are in a position to reduce the dying off of nerve cells and even to promote regeneration.

Friederike Süssig-Jeschor: So does that mean, thinking ahead to Christmas, that we should all forget about eating our Christmas roast and instead take propionic acid, or what should we understand by that?

Prof. Dr. med. Aiden Haghikia: Absolutely not! So we are not preaching a totally meat or fat-free diet now. It is more a matter of the proportions in the diet. That means you can celebrate Christmas without worrying and also enjoy your usual roast goose. However, if you were to celebrate Christmas for a whole year, you would change the microbiome, that is the composition of gut bacteria, billions - several thousand billion cells - in such a way, that it would be changed permanently and become dysbiotic, unbalanced.

We do not think that this change in the gut that is associated with neurodegenerative diseases, is a pathological condition... - there are the pathobionts, about which we know, for example, that they can trigger diarrhea or other illnesses - but rather the balance has been disrupted, that is, the eubiosis, the normal balance is disrupted, including after several days of Christmas celebrations.

But it returns back to eubiosis. However, when this composition is permanently altered, by habits, by taking antibiotics, by chronic changes to our diet, malnutrition, this balance can also be permanently altered, and this results in what is known as dysbiosis.

Friederike Süssig-Jeschor: Does a healthy gut flora exist at all? Can you say that?

Prof. Dr. med. Aiden Haghikia: It hasn’t been precisely defined yet and in addition, it can also be the case that one individual’s gut flora can be very different from another’s. In other words, a composition of bacteria that is healthy for you can be less so, or unbalanced, for me. We are still in the process of understanding and learning what the individual differences are.

Of course we know the main groups of bacteria, Bacteroidetes and Firmicutes. They are the main phyla of bacteria, but in terms of composition of the individual species it can be very different from one individual to the next, and we have to take care that we do not declare one species of bacteria as being pathogenic too soon, but rather there is a breakdown, a change in entire networks of bacteria.

Friederike Süssig-Jeschor: So in principle to begin with it is important to pay attention to eating healthily, that’s what I think you're saying. Or are we all at risk of developing a neurodegenerative disease at some point? Or which other factors also play a part in the emergence of a neurodegenerative disorder?

Prof. Dr. med. Aiden Haghikia: Neurodegeneration has several causes, in other words there is no one single reason why it happens. There is genetic predisposition, i.e. it is not a genetic, hereditary disease, but people have different dispositions towards developing a neurodegenerative disease and the interaction with environmental factors - and those actually pose the greatest risk - this interaction can lead to neurodegeneration.

And as far as the environmental factors are concerned, we overlooked them for a long time, and we did the same with the factors inside the body in the gut. Indeed the gut is in contact with the environment via the mouth and anus, and what we put inside ourselves, our diet, for example, can, of course, have effects, can pose a risk. We all, to return to your question again, have a disposition towards developing a neurodegenerative disease in older age.

However, we can also actively influence it, for example through a diet that is overall poor. If we look at it today in the Federal Republic, but also in the world as a whole.

Friederike Süssig-Jeschor: Are there also gender-specific differences that you have noticed?

Prof. Dr. med. Aiden Haghikia: With MS we know that women are three to four times more likely to be affected than men, especially in the early stage, in the relapsing phase. We know, that in the later phase, in the primary progressive phase, men are almost as frequently affected. In the case of Parkinson’s disease, men are somewhat more frequently affected, one and a half times to twice as often, and as we’ve already said, it is a disease of older age.

There will be a connection with the hormonal system. This has already been under investigation for a long time. There is as yet no clear finding as to whether estrogen tends to promote inflammation and testosterone degeneration or neurodegeneration.

Friederike Süssig-Jeschor: So there too, is an area of research that needs to be advanced. So let’s get specific now. There are now countless forms of diet: keto, paleo, vegan, vegetarian, gluten-free - what constitutes a healthy diet for the brain? And is it right that there is also a so-called anti-inflammatory diet? What would that look like?

Prof. Dr. med. Aiden Haghikia: To begin with, as far as these different forms of diet that are also popular on the internet are concerned... we are often asked about them by our patients in their consultations. I don't advise them, for various reasons. To begin with, in the best-case scenario, they do nothing at all. In the worst case - and very often that is what we see - they lead to symptoms of deficiencies, to hypovitaminosis for example, which can have the secondary effect of making the disease worse.

So I definitely would not advise strict forms of diet like this that promise a cure. There is a diet that is healthy for the brain. There is also a diet that is healthy for the immune system, which almost completely overlaps with a diet that is good for our hearts and vascular systems, in other words a primarily plant-based diet that is low in animal fats and low in meat.

That does not mean that we should refrain from eating meat altogether, but the majority of our diet should be plant based, and in a way that our gut is constantly kept busy. That does not mean pre-digested food, carbohydrates - rice, flour, pasta - the things that we normally eat as a carbohydrate side dish. Instead, forms of diet that challenge our gut, that also keep the microbiome busy, so that it digests our food for us.

Friederike Süssig-Jeschor: And how about things like fasting or vitamin supplements? Can they help MS or Parkinson's patients to feel fitter?

Prof. Dr. med. Aiden Haghikia: A balanced diet means that actually we absorb enough vitamins, the usual vitamins. So there is no particular need, unless there is an absorption problem. There are certain diseases that cause vitamins, vitamin B12, for example, to be improperly absorbed by the body. Apart from these situations, we actually absorb sufficient vitamins from our diet.

It is not really necessary to supplement. There are signs of deficiency, that we are only now recognizing, for example with the short-chain fatty acids. We weren’t aware of that as a form of deficiency... we can supplement that. There is no objection to fasting per se, if we do it in a balanced way. There are established forms. And we also know that there are initial indications that fasting can help to strengthen our immune regulation. Some first studies into this are now being conducted in the context of MS.

Friederike Süssig-Jeschor: To finish, I would like to talk about an aspect that concerns me about the subject as a whole. And we have already mentioned it to an extent. The World Health Organization has declared stress at work, but also stress in general, as one of the greatest threats of the 21st century. The fact today we are permanently “switched on”, that our gut in particular suffers because of this and these serious diseases like the ones we are talking about today are a consequence or could be a consequence. So in principle it is an unfortunate combination of factors, if you look at it that way. Do we need, therefore, to fundamentally adjust our standards of prevention and health promotion and in the best-case scenario start much earlier - move away from medicine that is aimed at curing disease and more towards prevention and medicine that strengthens health? How do you see it?

Prof. Dr. med. Aiden Haghikia: The short answer is yes. That is, stress, everyday stress, work stress all have a big impact, we know that now. A direct effect, in that various messenger substances are secreted that over the long term make the body sick. To put it in very global terms. Do we know the indirect consequences of stress too now? If you think, there are studies about it, that have also investigated how, for instance, a lack of sleep or even a transatlantic flight can lead to changes in the microbiome - as a response to this stress situation. That means, there are things that we can measure today. And on the one hand it is about prevention, you are right about that. That means not letting it happen in the first place. But, with stress, it’s also a case of how we deal with stress, coping strategies, to prevent it from becoming a permanent state, a chronic state, which then in turn has direct and indirect consequences for our health, gut health, and also for our brain health.

Friederike Süssig-Jeschor: Definitely a challenging subject and a subject that makes you think. About your own lifestyle too. Unfortunately, we have already reached the end of our interesting discussion. But I think that we still owe our listeners an answer to my opening question. That is, what was the better, more brain-healthy choice? My muesli, or your - I think it was - coffee and water - Professor?

Prof. Dr. med. Aiden Haghikia: Your muesli is definitely healthy. So you can keep going with that as long as you don’t switch it to bacon and fried egg every morning. My early morning diet, my body and my microbiome have got used to it, is also healthy for my needs, provided that I don’t eat bacon at 10 am, but instead, perhaps, your muesli, or an apple or a banana.

Friederike Süssig-Jeschor: And with that, thank you very much, Professor Haghikia! Bye! Hope to see you again!

Prof. Dr. med. Aiden Haghikia: Thank you very much!

Intro voiceover: Learn when you want to. The podcast about research at the University of Magdeburg.