Probiotics are live microorganisms that, when consumed in adequate amounts, may provide health benefits by supporting the balance of the intestinal or other microbiota.
Probiotics classically include strains of Lactobacillus and Bifidobacterium, which have been studied for their potential to support human health by modulating the gut microbiota. High-quality evidence from systematic reviews and meta-analyses shows that probiotics can influence microbiome composition, improve infant gut health when given maternally, support cognitive function in Alzheimer's disease, and help maintain gut flora during antibiotic use. Probiotics may also improve symptoms in functional constipation and modulate immune-inflammatory responses. Evidence supports strain-specific effects, with Lactobacillus and Bifidobacterium strains frequently studied. Safety profiles are generally favorable, with no significant increase in adverse events reported. However, some studies have low evidence levels or heterogeneity, and more high-quality, long-term research is needed to confirm benefits and clarify strain-specific effects.
Effects are strain-specific; benefits observed mainly in maternal-infant health and gut microbiota preservation during antibiotics.
Often studied alongside Lactobacillus; benefits include microbiome modulation and potential symptom improvement.
Evidence moderate; used in combination with lactulose for constipation.
Probiotics are generally safe with no significant increase in adverse reactions reported in clinical trials and meta-analyses. However, safety may depend on the strain and population. More long-term safety data are needed.
Some studies have low evidence levels or significant heterogeneity. Effects are strain-specific and not all strains have been equally studied. More high-quality, long-term randomized controlled trials are needed to confirm benefits and clarify mechanisms. Evidence for some conditions remains preliminary.