… then they will make you happy in turn!
Studies on the connection between our gut with all its microbes and our brain are accumulating with lightning speeds right now. The results are still a little confusing – which is no surprise, because we have so many different strains of microbes living in our intestines that it is hard to make sense of it all. But one thing is clear: there is a connection between what is happening in our gut and how we are doing.
Many might have had the “gut feeling” that there was some kind of interaction already. Many psychiatric conditions are known to be associated with digestive issues. And it seems rational: if there is billions of little creatures living inside of you, participating in how you digest your food and also secreting all kinds of hormones and chemicals – how would this not affect you?
Many conditions are linked to microbiota abnormalities: from addition and allergies over diabetes to Parkinson’s Diesease. Nowadays, we can add psychiatric conditions like anxiety disorders, depression, Autism and Schizophrenia to this list. However, for the longest time it was unclear what is the chicken and what the egg. And of course this isn’t a one way street: our behaviors influence our gut microbes and they in turn seem to influence our mood and behavior.
One amazing example of these close interconnection between gut and brain comes from epilepsy research. In severe cases of epilepsy, some patients benefit from switching of to a ketogenic diet, i.e. they have to avoid carbohydrates. Already after four days on this diet, the composition of their gut microbiome changes dramatically – and their susceptibility for seizures decreases. The reason for this seems to be, that specific bacteria strains, that are enhanced by the ketogenic diet, alter the balance between the neurotransmitters GABA and glutamate in the brain. How do they do this? The bacteria’s metabolism affects an enzyme in the gut that produces gamma-glutamyl amino acids. These are part of the glutamate production pathway. By this quite basic interaction, the gut bacteria influence the balance of neurotransmitters in the brain.
Other studies show that there is a close connection of what’s going on in the gut with mood and behaviors. Mice that have no gut bacteria (“germ free mice”) display anxious and less social behavior. If they receive a normal composition of gut bacteria, their behavior normalizes. If they receive gut bacteria from depressed or anxious individuals, they display depressed our anxious behaviors. Similarly, if they receive gut bacteria from obese mice (or humans), they become obese themselves.
At this point, the most pressing question of most people is: how can I make my own microbes happy? While it remains unclear, which composition of microbes is better and which worse for our mood and health, there is already a big body of work with suggestions how we can positively affect gut health.
The most basic tip is: eat fresh food. The less processed your food, the better. You don’t need to purchase expensive superfoods – just prepare your meals from fresh ingredients. The reason for this is not just the well-being of your gut inhabitants, but also that preservatives and other additions decrease the thickness of your gut lining, making it more susceptible for inflammation.
There are more ways how you can influence your gut health: consuming what is called “prebiotics” helps the development of a healthy microbiome. Especially fermented food helps the bacteria. A diet that contains many vegetables and fiber is good, high-sugar and high-fat diets are not. You can even influence your gut microbiome through exercise!
Try to take antibiotics only, if you really need them. If you take them, you can help your microbiome by supplementing with a good probiotics products. If you are pregnant, try not to eat a high-fat-high-sugar diet, because this will also influence your baby’s gut bacteria. Try giving birth vaginally, because C-section babies have altered gut microbiomes. Try breastfeeding as long as possible, because breastmilk contains very potent prebiotics.
“The Psychobiotic Revolution” by leading researchers in the field: Scott Anderson, Ted Dinan, John F. Cryan
Olson CA, Vuong HE et al., The Gut Microbiota Mediates the Anti-Seizure Effects of the Ketogenic DietCell, in press
Bäckhed, F., Manchester, J. K., Semenkovich, C. F., & Gordon, J. I. (2007). Mechanisms underlying the resistance to diet-induced obesity in germ-free mice. Proceedings of the National Academy of Sciences, 104(3), 979-984.
Ridaura, V. K., Faith, J. J., Rey, F. E., Cheng, J., Duncan, A. E., Kau, A. L., … & Muehlbauer, M. J. (2013). Gut microbiota from twins discordant for obesity modulate metabolism in mice. Science, 341(6150), 1241214.
Marin, I. A., Goertz, J. E., Ren, T., Rich, S. S., Onengut-Gumuscu, S., Farber, E., … & Gaultier, A. (2017). Microbiota alteration is associated with the development of stress-induced despair behavior. Scientific reports, 7, 43859.
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