PROBIOTICS. PROBIOTIC BACTERIAL CULTURE COMPLEX

Key conclusions

• The authors indicate that probiotics in sport are considered primarily in the context of supporting gut health and immune function, not as a classic supplement that directly improves performance.
• The document emphasises that probiotic effects are strain dependent and dose dependent. The authors also note that the product label should include the genus, species and strain of each microorganism, together with the quantity declared at the end of shelf life.
• In athletes exposed to heavy training load, selected probiotic strains may reduce the number of episodes, severity or duration of upper respiratory tract infections, especially during periods of heightened physical, mental or environmental stress.
• The position statement also notes that intense, prolonged exertion, particularly in high temperatures, can increase intestinal permeability. The authors emphasise that selected probiotic strains may support gut barrier integrity in athletes.
• Among studies on recovery after muscle-damaging exercise, the authors cite the combination of Bifidobacterium breve BR03 ratio, and Streptococcus thermophilus FP4.In a study involving trained men, supplementation with 5 × 10⁹ live cells of each strain daily for 3 weeks was linked to better maintenance of isometric peak torque and range of motion in the acute recovery phase, and to a reduction in interleukin 6 concentration.
• Regarding Lacticaseibacillus rhamnosus GG the position statement cites studies in which this strain was linked to improvements in selected aspects of gut health in athletes. In a study of marathon runners, no effect was observed on the frequency of respiratory tract infections or gastrointestinal episodes, but the duration of post-marathon gastrointestinal symptoms was reduced.
• At the same time, the document emphasises that the influence of probiotics on direct performance parameters and sports outcomes is less clear. The authors point out that results are mixed: of 24 studies assessing some performance parameter, 17 showed no effect and 7 recorded improvement.
• In their summary the authors judge that the available studies provide moderate evidence that probiotics may bring certain clinical benefits in athletes and very physically active people, but their use should be targeted and based on specific strains, not on the general assumption that every probiotic will work the same way. 

Key conclusions

• After 21 days of supplementation with the S. thermophilus FP4 and B. breve combination, a smaller decline in strength parameters was observed after muscle-damaging exercise. Mean peak isometric torque was higher versus placebo by roughly 11% at 24 hours, 12% at 48 hours, and 8% at 72 hours of recovery.
• Supplementation was also associated with better maintenance of range of motion during the recovery window. Compared with placebo, a favourable effect was recorded on resting arm angle at 24 and 48 hours after exercise. The effect on flexion range of motion was less clear.
• The study showed a reduction in resting interleukin 6 concentration after 21 days of supplementation, and this effect persisted up to 48 hours after exercise. The authors note, however, that the influence of supplementation on interleukin 6 changes induced by the exercise itself was unclear.
• Not every analysed indicator improved. The effect on muscle soreness, creatine kinase and several other recovery markers was inconclusive, so a uniform effect across all assessed parameters cannot be claimed.
• The publication suggests that the combination of B. breve BR03 and S. thermophilus may be of interest for recovery after intense eccentric exercise, particularly when the goal is to limit the drop in exercise capacity in the days following training.
• The authors emphasise, however, that this was a study carried out on a small group of resistance-trained men in a specific eccentric exercise model, so the results should be interpreted cautiously and not transferred automatically to every athletic population.

Key conclusions

• The analysis included 9 randomised clinical trials covering 335 athletes in total, with intervention duration from 28 to 90 days. The studies used various probiotic formulations containing at least one strain from the Bifidobacterium or Lactobacillus.
• The authors showed that probiotic supplementation was associated with a significant reduction in TNF-α concentration.
• The meta-analysis also recorded a significant reduction in IL-10 concentration.
• At the same time, supplementation was associated with a significant increase in IFN-γ and in salivary immunoglobulin A, a marker of mucosal immunity.
• For other markers such as IL-1β, IL-2, IL-4, IL-6, IL-8 and C-reactive protein, no significant changes were shown in the overall analysis after probiotic supplementation. This shows that the influence of probiotics on the immune system and inflammation is selective, not uniform across all parameters.
• Subgroup analysis showed that the significant reductions in TNF-α and IL-10 were more visible in shorter interventions, lasting under 6 weeks.
• The authors also note that the result depended on the timing of sample collection after exercise. With collection delayed at least to the day after exercise, significant reductions in TNF-α and IL-10 were observed, while with collection immediately after exercise, significant reductions in TNF-α, IL-8 and IL-10 were recorded.
• The authors emphasise, however, important limitations of this analysis. The studies used different strains, doses, sports, supplementation forms and evaluation protocols, and some results showed significant heterogeneity. The conclusions are therefore best treated as general data on the possible influence of probiotics on selected immune and inflammatory markers in athletes, not as a basis for attributing identical effects to every probiotic formula.

Key conclusions

• The authors indicate that probiotics may support sports outcomes primarily indirectly: through better recovery after intense training, immune support, reduction of gastrointestinal symptoms, and improved absorption and use of selected nutrients.
• The publication emphasises that the most convincing data concern endurance exercise. In some studies, probiotic supplementation was linked to improvements in aerobic capacity, longer time to exhaustion, or better results in running, cycling and swimming.
• The authors also describe that data on strength and power are more limited, but some results are promising. The cited studies observed improvements in mean power, a favourable effect on vertical jump, or better maintenance of exercise capacity after intense exertion. At the same time, the authors note that most of these studies assessed probiotics combined with protein, with little research on the standalone effect of probiotics.
• One important mechanism may be the influence on post-exercise recovery. In some studies, probiotic supplementation was linked to smaller increases in markers of muscle damage and inflammation, less muscle soreness, and a faster return of exercise capacity after heavy training.
• The publication also highlights a possible influence of probiotics on the absorption and use of nutrients, especially protein, branched-chain amino acids and carbohydrates. The authors cite studies in which supplementation was associated with an increase in circulating amino acid concentrations or a small improvement in glucose oxidation during exercise.
• The authors indicate that probiotics may be particularly interesting in the context of gastrointestinal symptoms, which are common especially in endurance athletes. Some studies observed fewer or less severe gastrointestinal symptoms during training and competition.
• The review also describes the possible role of probiotics in immune function, especially in athletes training intensely or over long periods. The cited studies suggested reductions in the frequency or severity of upper respiratory tract infections, but the authors emphasise that the number of such studies is still limited.
• The authors also note that probiotics may potentially influence mental wellbeing and stress tolerance. Individual studies described reductions in stress and anxiety levels and improvements in attention, but this area also requires further research.
• At the same time, the authors stress that probiotic effects aren't uniform, and the available data differ depending on strain, dose, supplementation duration, training level and type of exercise. For this reason, probiotics shouldn't be treated as a single, uniform category with identical action.
• In the final conclusions, the authors summarise that current data suggest potential benefits of probiotics in sport, especially in endurance. At the same time, they emphasise that this is a narrative review without a systematic literature search, and further research should better account for differences between strains, formulations and the characteristics of the athletes themselves.

Key conclusions

• The authors indicate that the most repeatable benefits concerned respiratory tract infections. Several studies observed shorter infection duration, fewer days with symptoms, or lower frequency of infectious episodes, although not every intervention produced this effect.
• Regarding gastrointestinal symptoms, results were also partly favourable but inconclusive. Some studies reported shorter symptom duration, fewer days with discomfort, or favourable changes in selected gut barrier markers, while others showed no significant changes.
• In immunity and inflammatory markers the picture was mixed. Most studies showed no clear changes in the classical immune markers. Individual papers observed higher salivary immunoglobulin A concentration, favourable changes in interferon gamma, reduced interleukin 6, or a drop in C-reactive protein.
• The authors note that evidence on the direct influence on sports outcomes is limited. The review indicates that 7 studies assessed parameters related to exercise performance, but the results were inconsistent and the authors summarised this area as poorly documented.
• Some papers suggested benefits in recovery or time to exhaustion, but many showed no effect on capacity, strength or maximum oxygen uptake. The authors also emphasise that in one of the studies the difference in time to exhaustion is difficult to unambiguously attribute to the intervention itself, because no pre-supplementation measurement was taken.
• In the discussion, the authors conclude that probiotic supplementation was more often linked to improvements in health indicators that matter for training continuity, such as respiratory tract infections, gastrointestinal symptoms or selected immunity markers, than with direct improvements in sports performance.
• An important limitation of the whole research area was the high heterogeneity of protocols. The authors highlight differences in the strains used, doses, supplementation duration, populations and assessed endpoints, which makes it difficult to identify a single optimal supplementation regimen.
• In the evidence quality assessment table, the authors indicate that data quality for respiratory tract infections was moderate, while for mucosal immunity, the gastrointestinal tract and exercise-related parameters it was rated as high. At the same time, the review itself emphasises that for exercise parameters results remained inconsistent, so this rating shouldn't be read as confirmation of an unambiguous improvement in sports outcomes.

Key conclusions

• Badanie dotyczyło bezpośrednio szczepu Bifidobacterium lactis BS01 oraz jego mikronizowanych komórek.
• Autorzy oceniali wpływ BS01 na monocyty, czyli komórki uczestniczące w odpowiedzi immunologicznej.
• Mikronizowane komórki BS01 wpływały na ekspresję markerów powierzchniowych związanych z polaryzacją monocytów/makrofagów.
• W modelu laboratoryjnym obserwowano zmiany sugerujące aktywację monocytów po kontakcie z mikronizowanymi komórkami BS01.
• Autorzy analizowali również wpływ BS01 w warunkach stresu oksydacyjnego in vitro.
• Wyniki badania wskazują, że mikronizowane komórki BS01 mogą oddziaływać na wybrane mechanizmy komórkowej odpowiedzi immunologicznej.
• Badanie przeprowadzono w modelu in vitro, bez udziału ludzi.