Probiotics contain microorganisms, and most of these little microorganisms are similar to the naturally-occurring, beneficial bacteria of the human gut. Probiotics often contain a variety of strains, including those of the Lactobacillus, Bifidobacterium and Saccharomyces species.
When it comes to probiotics, quality is definitely superior to quantity. I often see people with cheap, poorly-strained, 50-billion probiotics. More is not necessarily better! Most research around probiotics is focused on the use of particular strains, not just the flora count.
The strongest evidence for probiotics comes through a number of meta-analyses of randomized, controlled trials demonstrating the effectiveness of particular strains in preventing antibiotic-associated diarrhea (including Clostridium difficile infection) (1), treating infective diarrhea (in both adults and children) (2), and prevention of traveler’s diarrhea (3).
A number of randomized, controlled trials also support the use of probiotics in inflammatory bowel disease (IBD; for chronic pouchitis flare-ups) (4), prevention of diarrhea in infants attending daycare (5), and management of atopic eczema (6).
Probiotics can also be useful in management of a variety of skin conditions (rosacea, acne), vaginal conditions (bacterial vaginosis, vulvovaginal candidiasis) and oral health.
For those who have issues/restrictions with cow’s milk, ensure your probiotic is free of cow’s milk protein, which is often used as a growth substrate for probiotics.
To note, probiotics should always be taken 2-4 hours away from antibiotics and ALWAYS taken with food.
Probiotics are not indicated for everyone, so speak to a healthcare provider to ensure these are appropriate for you. As already discussed, it really does matter which strains are in your probiotic, so seek guidance when using probiotics therapeutically.
Reference(s): (1) PMID: 12052801, (2) PMID: 21069673, (3) PMID: 17298915, (4) PMID: 10930365, (5) PMID: 15629974, (6) PMID: 11297958, (7) PMID: 28762696.