If you've ever had chronic pain, inflammation, or digestive problems, you may have been told that you should ditch your "Western" (inflammatory) diet for one that is more anti-inflammatory, plant-rich, and overall better for a healthy gut flora. But how exactly should you feed your gut flora? And is the Mediterranean diet the best option?

What is the Mediterranean Diet and Why do People Choose it?

The Mediterranean Diet is inspired by the traditional eating patterns of countries bordering the Mediterranean Sea, such as Greece, France, Spain and Italy. Those who follow the Mediterranean style embrace the consumption of fibre and nutrient-rich products such as fruits, vegetables, whole grains, legumes, nuts and seeds. On top of that, they enrich the flavour of their meals with plant-based fats such as extra virgin olive oil. On the other hand, they limit the consumption of meats, processed foods, added sugars, and refined grains.
 
Nowadays, more and more people who are looking to improve their overall health parameters decide to switch from a Western to a Mediterranean diet. While the former seems to be correlated with enhanced gut permeability, AKA ‘leaky gut’ which increases inflammation and could lead to diseases, the latter is linked to numerous health benefits.
 
Following a Mediterranean diet also seems to promote heart health by lowering the risk of cardiovascular disease, hence heart attacks. In fact, it may help to reduce both diastolic and systolic blood pressure (thus, overall blood pressure) while reducing the presence and progression of plaque in the arteries. 
 
The Mediterranean diet is not only beneficial for your heart health, but it also seems to play a role in decreasing the risk of developing type 2 diabetes. How? Literature indicates that it reduces insulin resistance, a condition that impairs the uptake of blood glucose into cells. Insulin resistance causes the cells to be less responsive to insulin, meaning that the cells will not, and cannot, efficiently take up glucose from our blood. This means that glucose is left to roam in your blood, increasing your blood sugar levels. Glucose is a sugar used by the cells as a substrate to produce energy. To compensate, more insulin will be produced by the pancreas. Over time, as blood sugar levels rise, the risk of developing type 2 diabetes is increased, along with many other health consequences. Therefore, maintaining the insulin level within the healthy range is vital to reducing the risk of the onset of diabetes type 2.
 
Interestingly, the Mediterranean Diet can also help preserve brain functions by acting upon cognitive impairment and memory decline. Consequently, it may reduce the overall risk factors that lead to the onset of neurological chronic diseases such as Alzheimer's. Among the several benefits, adopting a Mediterranean lifestyle seems to increase memory, attention, and overall mental acuity supposed to be protective against cognitive decline and, hence beneficial for mental health.
 

How Does the Mediterranean Diet Associate with Gut Microbiota?

Several studies found strong correlations between a healthy gut microbiome and the composition of individuals’ diets. As an example, the Mediterranean Diet may help beneficial gut bacteria flourish and thrive.
 
A recent study suggests that following the Mediterranean diet may alter intestinal health in ways that contribute to a healthier gut microbiome. Importantly, the Mediterranean diet's potential benefits to gut health are not limited to older people, as has been shown in other studies on this topic. Research that focused on investigating the consumption of fruits and vegetables, healthy fats, and whole grains, which constitute the main pillars of a Mediterranean diet, increases the abundance of beneficial gut bacteria. These friendly microbes are linked to better brain function, memory and cognitive disabilities, as well as a decrease in chronic low-grade inflammation, a condition that may include the development of chronic diseases such as diabetes.
 
New research found that people who follow a Mediterranean Diet tended to have a higher abundance of types of gut bacteria linked with healthy ageing. It has been found that individuals who follow the Mediterranean Diet for one year have a healthier gut microbiome and overall better health parameters.
 
It may be argued that people who follow the Mediterranean diet have a distinctive gut microbiome signature that may prevent the onset of chronic and non-communicable diseases such as diabetes, cardiovascular diseases, and neurological diseases.
 
Researchers at University Medical Centre Groningen in the Netherlands assessed eating habits and gut bacteria in over 1,400 participants and found that a Mediterranean-style diet was associated with healthier gut microbiota. By the end of the study, they found that the Mediterranean-style diet was linked to a greater abundance of healthy gut bacteria, and also lower levels of inflammation markers, which are typically associated with conditions such as irritable bowel syndrome (IBS), Crohn's disease, and ulcerative colitis. Those who followed diets high in meat, sugar, or processed foods (a more Western-style diet) had lower levels of good gut bacteria, according to the latest research, and higher levels of inflammatory markers.
 
Adopting a healthier lifestyle such as the Mediterranean and plant-based diets is associated with higher levels of beneficial bacteria in the gut, which have anti-inflammatory properties. The conclusion is that a Mediterranean diet offers a healthy, varied selection of foods that helps to boost the number of good bacteria in the gut. As a result, microbes in our gut thrive when we regularly eat foods that are part of a Mediterranean diet. It is reasonable to suggest that this positive modulation in gut microbiome diversity, composition, and function is a major driver underlying the health effects of a Mediterranean diet for hosts. Given the benefits the Mediterranean diet has for our intestinal health too, it makes sense that eating this way might improve our cognitive capabilities, as the gut-brain axis shows us just how tightly linked the two are. Overall, eating in the Mediterranean way may enhance your overall health, while also benefiting your gut microbiome.
 
Although further studies are needed, it has been found that healthier dietary patterns strongly affect the composition and metabolic functions of the gut microbiome, suggesting an opportunity for the prevention and treatment of a variety of lifestyle-related disorders based on the modulation of the gut microbiota. In summary, there is a growing understanding that adhering to the Mediterranean diet could potentially influence health outcomes by positively impacting the gut microbiome. This interaction might lead to an enhanced overall healthy gut microbiota profile, subsequently contributing to better well-being. Furthermore, the Mediterranean diet has demonstrated the capability to decrease the presence of gut bacteria linked to elevated risks of inflammation, intestinal cancer, insulin resistance, fatty liver, and cellular damage.

Reference

1. Bolte, L. A., Vila, A. V., Imhann, F., Collij, V., Gacesa, R., Peters, V., ... & Weersma, R. K. (2021). Long-term dietary patterns are associated with pro-inflammatory and anti-inflammatory features of the gut microbiome. Gut, 70(7), 1287-1298.

2. Valdes, A. M., Walter, J., Segal, E., & Spector, T. D. (2018). Role of the gut microbiota in nutrition and health. Bmj, 361.

3. Zhao, M., Gönczi, L., Lakatos, P. L., & Burisch, J. (2021). The burden of inflammatory bowel disease in Europe in 2020. Journal of Crohn's and Colitis, 15(9), 1573-1587.

4. Hardman, R. J., Kennedy, G., Macpherson, H., Scholey, A. B., & Pipingas, A. (2016). Adherence to a Mediterranean-style diet and effects on cognition in adults: a qualitative evaluation and systematic review of longitudinal and prospective trials. Frontiers in nutrition, 22.

5. Singh, R. K., Chang, H.-W., Yan, D., Lee, K. M., Ucmak, D., Wong, K., Abrouk, M., Farahnik, B., Nakamura, M., Zhu, T. H., Bhutani, T., & Liao, W. (2017). Influence of diet on the gut microbiome and implications for human health. Journal of Translational Medicine, 15(1). https://doi.org/10.1186/s12967-017-1175-y;

6. Fito Colomer, M., Sun, Q., Merino, J., Guasch-Ferré, M., & Salas-Salvadó, J. (2017). Dietary polyphenols, mediterranean diet, prediabetes, and type 2 diabetes: a narrative review of the evidence. Oxidative Medicine and Cellular Longevity, 2017(2017).