Probiotics are not all the same. For this reason, it is important to know the strain to which it belongs, the quantity of microorganisms per daily dose and the scientific evidence to support their resistance to gastric acidity.
The World Health Organization defines probiotics as those microorganisms that are able, once ingested in the necessary quantities, to perform beneficial functions. A probiotic product must contain live organisms and be accompanied by scientific evidence attesting its benefits and safety for humans.
To be called “probiotics”, microorganisms that can be used in food supplements must have specific characteristics:
- Be traditionally used to supplement intestinal microflora in humans;
- Be safe to use; that is, they must comply with the QPS (Qualified Presumption of Safety) criteria and must not be carriers of acquired and / or transmissible antibiotic resistance;
- Be active in the intestine in quantities that multiply.
Warning: not all strains are the same! Those with greater scientific evidence and consequently most used are the Lactobacillus (acidophilus, reuteri, rhamnosus, paracasei, delbrueckii subsp. bulgaricus, alivarius, casei, plantarum) and the Bifidobacterium (longum, bifidum, breve, infantis, animalis, lactis). However, the probiotic attribute has also been recognized for the Streptococcus, Lactococcus and Propionibacterium genera. Instead, concerns have been raised about the genera Bacillus and Enterococcus. It is therefore necessary that the user pays attention to the content of the probiotic he/she is buying.
Furthermore, it should be ensured that the microorganisms in question are resist gastric acidity, pancreatic juices and bile salts. The most resistant strains to bile salts, thanks to their enzymatic action, are Lactobacillus, Bifidobacterium and Enterococcus (although the latter are to be avoided according to the Istituto Superiore di Sanità in Italy). The resistance of the strain used is vital. In fact, if the bacteria die as soon as they come into contact with gastric fluids and their extremely acidic pH, they will not bring any benefit to the body (that is, “normalization”). It is necessary that they arrive vital in the intestine in order to colonize it and restore the normal balance of the intestinal flora.
Probiotics should not be confused with lactic ferments or bacteria that are contained in yoghurt (milk, soy) or other foods. They are generally used synonymously but they are not. Lactic ferments are bacteria capable of producing lactic acid starting from the fermentation of lactose. In fact, they are “foods” that contain microorganisms capable of “digesting” lactose. Unlike probiotics, lactic ferments die on contact with gastric juices and do not reproduce in the intestine. Therefore, taking a probiotic is different from consuming a yogurt or other fermented foods, although the latter can help improve the digestion of dairy products, combat constipation and diarrhea, gastrointestinal complications of flu and abdominal bloating.
Another point to consider is the number of microorganisms contained in the chosen supplement. In fact, the Italian Ministry of Health has asserted that, to bring benefits to our intestinal flora, they must be taken in the amount of at least 109, or 1 billion microorganisms per strain contained in the formulation. There are restrictions on the minimum of bacteria needed but not on the maximum. For this reason, people commonly think that “more is better”. This is not necessarily true. What matters is the quality of the microorganisms (as previously written). Therefore, one must be careful of the excessively high numbers declared on some labels, sometimes misleading.
The patented strains possess studies that ascertain the genetic stability, acidophilic (the ability to resist gastric juices) and ability to adhere to the intestinal walls of probiotic strains. The patented probiotics, in most cases, are therefore produced with experimentally verified quality.
The presence of prebiotic fibers improves the probiotics’ ability to survive. They are non-digestible substances naturally contained in some foods and promote the growth of one or more bacterial species useful for the development of the microbiota. In addition, they improve the absorption of some minerals (Calcium, Iron and Magnesium), normalize intestinal functions and protect against inflammation and infections affecting the intestine and colon. The most used ones are beta-glucans, fructans, fruit-oligosaccharides (FOS), resistant starch and inulin. For these multiple reasons, it is therefore preferable to take a symbiotic supplement, that is, a mix of probiotics and prebiotics.