The word probiotic derives from the Latin and Greek languages, meaning for life. But what
Probiotics are living microorganisms that, when administered in adequate amounts, confer benefits to health. There are several microorganisms used as probiotics. Most probiotics with
clinical application are species of seven main categories (genera): Lactobacillus,
Bifidobacterium, Saccharomyces, Streptococcus, Enterococcus, Escherichia, and Bacillus.
In the case of probiotics, it is important to use the denominations of strains, since the most
serious approach on the evidence of probiotics is to be able to associate benefits with
certain strains or combinations of probiotic strains in an effective dose.
Commercialized probiotics are composed of a single microbial species or a combination of
multiple species. Probiotics can be ingested through diet – they are present in foods such as
yogurts and fermented milks (kefir, for example) and in some industrially fortified foods. On
the other hand, probiotics can be administered as food supplements or pharmacological
preparations – in this regard, its use is directed to specific pathologies.
The mechanisms of action of probiotics are closely related to the modulation of the human
intestinal microbiota. Probiotics have been shown to have an important influence on the
restoration and maintenance of the intestinal microbiota through antimicrobial and immune
effects, whose mechanisms of action are still imprecise.
Probiotics have the ability to repair microbiota changes associated with various pathological
states, and their efficacy in the prevention and treatment of numerous pathological
conditions associated with certain dysbiosis has been revealed.
Diarrhoea is a common adverse effect of the use of antibiotics. Antibiotics interfere with the
balance of the intestinal microbiota, making the intestinal barrier more permissive, which
facilitates invasion by pathogenic microorganisms. The use of probiotics arises in order to
restore the balance of the intestinal microbiota and strengthen the stability of the barrier
when using antibiotics in order to prevent the onset of diarrhoea. Moreover, there is scientific
evidence to prove the efficacy of Lactobacillus GG, L. Casei DN-114001, and S. Boulardii in
the prevention of infantile and adult diarrhea in some specific contexts.
Probiotics of S. boulardii and L. rhamnosus have a proven efficacy in the treatment of
infectious diarrhea in children; however, since acute gastroenteritis tends to resolve
spontaneously and the clinical impact of its use is moderate, its use should be questioned.
In a review article published in 2007, it is noted that adjuvant therapy with probiotics, in the
context of anti-Helicobacter pylori therapy, significantly reduces side effects related to this
treatment, without, however, having a major impact on the eradication rate of the said
New evidence suggests that the intestinal microbiota can affect several non-gastrointestinal
pathologies, thus establishing a link between these diseases and the gastrointestinal tract.
Many studies have shown that probiotics can reduce bacterial vaginosis, prevent atopic
dermatitis, reduce oral pathogens and tooth decay, and reduce the incidence and duration of
common upper respiratory tract infections. Metabolic diseases such as type 2 diabetes
mellitus, hypercholesterolemia and obesity demonstrate promising but still inconsistent
Each one of the benefits presented above can also be applied to athletes. Moreover, the
International Society of Sports Nutrition states that “certain probiotics strains can increase
absorption of key nutrients such as amino acids from protein”, which can be of use to athletic
populations. When the training load is extreme, and in certain situations, such as travelling,
sleep disturbances or environmental changes, the immune system of athletes can be
depressed, promoting exposure to pathogens. The gut is the “household” of 70% of the
immune system – therefore, probiotics can promote a healthy immune response. In athletes,
the role of probiotics on upper respiratory tract infections prevention and treatment has also
been a theme of debate. Similarly, certain probiotics can sustain the integrity of gut-barrier
function. Regarding recovery from exercise, some strains seem to improve recovery.
Generally speaking, most probiotics are safe and major adverse effects associated with their
consumption are not described in the literature. The consumption of probiotics by healthy
individuals and athletes aims at primary prevention – however, it should be taken in a careful
manner and after an evaluation process. Caution must be taken by immunocompromised
individuals and patients with invasive medical equipment.
The content of this article does not constitute medical advice by a registered healthcare professional. Please consult a qualified sports nutritionist before starting any new diet, exercise or training programme.