An essential part of proper maintenance of the microbiota is first of all a varied diet, healthy and rich in dietary fiber, without necessarily having to give up a bit of overindulgence every now and then. Notwithstanding different personal choices, there are many foodstuffs that constitute an excellent "growth medium" for the gut microbiota:
- it is essential to eat as many different types of vegetables as possible. "Coloring" the dishes with different, local and seasonal vegetables like peppers, carrots, zucchini, beets, cucumbers, cabbage, cauliflower, pumpkin, and potatoes of all kinds, from brown to purple must not be just a decoration of the dish, but a constant with every meal. Even protein sources such as eggs, fish, white meat, tofu and seitan should be accompanied by fresh vegetables.
- Carrots, onions, garlic, red cabbage, green and black olives and nuts of all kinds (like peanuts and almonds) are the preferred foods of the bacteria most beneficial to our intestines. The fat par excellence is untreated extra virgin olive oil (EVO).
- Fermented foods like sauerkraut, which are historically present in the diets of all cultures, should also prevail among the foodstuffs that should also be on the table. Fermented cheeses like gorgonzola, Roquefort and parmesan are excellent prebiotic foods, as are kefir and yogurt (the food types, which should not be confused with the lactic acid bacteria dietary supplement versions. See FAQ).
- Legumes and cereals are another category of foodstuffs that were once the basis of normal nutrition, but which today are often relegated to serving only occasionally. Barley, millet, spelled, lentils, beans and peas are all suppliers of fiber and beta-glucans, which are very important for sustenance of the microbiota.
- All fruit is a good source for the sugars preferred by bacteria. Bananas are rich in digestive-resistant starch, apples are rich in vitamins and nutrients, avocados are very rich in fiber, fatty acids, vitamins and minerals. Seasonal items from different geographic areas like citrus fruits, kiwis, grapes and figs all nourish the gut microbiota in a varied, appropriate manner.
A plant based diet, for example, increases the presence of beneficial SCFA-producing species. A diet consisting mainly of animal derivatives, especially if excessively processed, instead tends to cause an increase in bacteria such as Bilophila and Ruminococcus that are not very friendly to intestinal eubiosis.
A diet rich in unsaturated fats (extra virgin olive oil and avocado, for example) increases the level of Lactobacilli and Bifidobacteria and also contributes to maintain a balanced lipid metabolism. On the contrary, a diet rich in saturated fats, like butter and margarine, increases bacteria such as Bilophila and Bacteroidetes, which can lead to undesirable health effects.
To sum up, the western diet reduces useful bacteria such as Eubacteria, Bifidobacteria and Lactobacilli while the Mediterranean diet, which is rich in fish, fruit, vegetables, dietary fiber and dried fruit properly nourishes the microbiota and enriches it with friendly, beneficial bacteria.