Among other things, this insight has led to an abundance of so-called probiotic products in supermarkets, pharmacies, and drugstores. These products claim to introduce healthy bacteria into our intestines. That sounds a whole lot better than it actually is.

Greatest positive change 

British research has shown that drinking one of the well-known dairy drinks from the supermarket barely leads to any changes in the composition of intestinal bacteria. Clear changes were evident among the group of test subjects who ate extra leek, onion, garlic, asparagus, and artichokes. These vegetables are naturally rich in the probiotic Inulin. The greatest positive change, however, was found in the test group that drank the milk drink kefir.

Kefir is made by adding kefir grains to dairy such as milk. This causes the milk to ferment and produces a fresh, sourish, and creamy milk drink, packed with healthy yeasts and bacteria. Because of the high acidity of fermented products, the bacteria are able to survive the acid environment of the stomach and reach the intestines. In non-fermented products, like the famous dairy drinks, any healthy bacteria would cease to exist once they reached the acid stomach.

Fermentation as a precursor of the refrigerator 

Fermentation is the process through which bacteria, fungi, or yeasts convert certain substances in a product, thus changing its acidity, flavour, smell or appearance. It is used to make products like yoghurt, cheese, beer, bread, tempeh, wine, sauerkraut, soy sauce, dried sausage, and vinegar.

Before the invention of the refrigerator, fermenting food was one of the most common ways to extend the life of perishables.

In the Caucasus region, kefir had been known for centuries as “the drink of the centenarians” before it was discovered by the general public. During the seventies, a kefir or yoghurt culture could be found on the worktop in nearly every Dutch kitchen.  Nowadays, kefir grains can be purchased online.