This is how the brain-gut axis works

Everyone knows the troubled bowels when you are nervous, or the butterflies in your stomach when you are in love. There is a very lively intercourse between the gut and the brain, the so-called brain-gut axis. Brummer says: “The close cooperation between the brain and the gut means that there is really no separation between physical disorders and mental disorders. In my research work I have increasingly looked at the relationship between nutrition, the microbiome, the gut and the brain. In the first instance, what I strive for is a better treatment for diseases and complaints of the gut, such as irritable bowel syndrome (IBS). But my research also focuses on the question of whether you can optimize brain function via the gut. For example, can you reduce stress and depression with the right diet, or can you improve mood if you take better care of your gut?”

Depression and the Microbiome

Brummer and his research group recently conducted an exploratory study into the effect of diet on depression. He explains the underlying mechanism: “During depression and stress, low-grade inflammation occurs in the body. These are inflammations that do not give you a fever or pain, but that do cause inflammatory reactions in the body. Tryptophan is involved in these inflammatory reactions. This is a substance that, under the right conditions, is converted in the body into serotonin, a substance that improves our mood. When there is inflammation in the body, less tryptophan is converted to serotonin. As a result, the mood deteriorates, and this effect also occurs with those low-grade inflammations. You may think: ‘then you give a medicine with extra tryptophan?’ But unfortunately that doesn’t work, studies have already shown. Here at the university, we now want to investigate whether we can reduce low-grade inflammation in the body with the right nutrition, so that more serotonin is produced and thus improves mood.”

Food against inflammation

What does such a diet look like? Brummer: “We start from an anti-inflammatory diet, in other words an anti-inflammatory diet. It is a healthy, complete food with many pure and unprocessed ingredients. That is first of all oily fish, because of the omega 3 fatty acids that have a direct positive effect on the brain. But this food also contains a lot of vegetables, whole grains, fiber-rich legumes and, for example, berries. These products contain fibers that have a beneficial effect on the intestines. We use typical Scandinavian regional products in this food.” This diet is also referred to as the “New Nordic Diet” and is considered by scientists to be just as healthy as the Mediterranean diet. The Health Council of the Netherlands has also used this dietary pattern when drawing up the Guidelines for a good diet.

Brummer continues: “Nutrition research has always been very difficult, but we really made it difficult for ourselves in this study. We have tried not to influence the participants. One group was given the anti-inflammatory diet, the control group was given a regular diet, and we didn’t tell them what diet they were getting. Because if you think you’re getting super healthy food, that of course has an effect in itself. The exploratory study was successful, although some participants were aware that they were eating extra healthy. That’s why we’re going to add some lettuce leaves here and there in the control group to make that regular food look extra healthy. And then we can start with the real study. At least, as soon as the coronavirus allows it.”

From gut to brain – and vice versa

The fact that you can inhibit low-grade inflammation with the right nutrition is an insight that has only been growing in the last 10 years. “It has been known for some time that fish fatty acids have a positive effect on the brain. But anti-inflammatory foods, with a lot of fiber, also have a direct positive effect on the microbiome in your gut, and therefore also on the brain,” explains Brummer. ”I give a lot of training about this concept to doctors, nurses and practice nurses. It’s a shame it hasn’t been picked up like that yet. With the right nutrition, so many positive effects for the body and the mind can be achieved. And it also works the other way around, from brain to gut. For example, it can be beneficial for people with an irritable bowel to use antidepressants in low doses. This is already prescribed by some doctors, but it could be done more often. The antidepressants have a positive influence on the brain-gut axis, which makes the intestines calmer.’

A look into the future

The study on depression is just one example of the studies under Brummer’s care. For example, there is also a study in which people are given probiotics for several weeks, after which the effect on the brain in the event of stress is measured with an MRI scan. “There is certainly an effect”, says Brummer, “But I can’t say too much about it, because the study has not yet been published. There is a future in this area. You may also be able to use the relationship between the gut and the brain in people with autism or ADHD. There are already indications for this, but they are not yet strong enough. What works for one person won’t work for another. We need to find out: why do some people react much more strongly to food or probiotics than others? And can we offer a tailor-made treatment in the future? That is our aim.”

The positive look

Brummer is optimistic: “I expect that we can use the insights about the gut-brain axis in the prevention and treatment of chronic diseases. But there’s something that I actually think is much more important: I wish we would pay a lot more attention to the acutely positive effect that food can have on the mind. Because it is of course very important that you can reduce the risk of cardiovascular disease in the long term through healthy eating. But you feel gloom or stress now. It would be nice if more and more people realize that they can influence this by eating the right things.”