probiotic
Probiotics: Strains, CFU, Timing and Safety
Also known as probiotic supplements, Lactobacillus, Bifidobacterium, Saccharomyces boulardii, live cultures, good bacteria
Short answer
Probiotics are live microorganisms, mostly Lactobacillus and Bifidobacterium bacteria plus some yeasts [1]. Their effects depend on the exact strain, and a higher CFU count is not necessarily better [1][2]. Some yogurts contain them. People who are seriously ill or immunocompromised, and premature infants, have a higher risk of serious infection [1].
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What is Probiotics?
Probiotics are live microorganisms that are intended to have health benefits when eaten or applied to the body [1]. Most are bacteria from the Lactobacillus and Bifidobacterium groups; some are yeasts such as Saccharomyces boulardii [1]. Researchers think they may work in the gut by supporting the community of microorganisms, making certain substances and influencing the immune response [1]. Their effects are specific to each strain [2].
Forms of Probiotics you'll see on labels
Strain name (genus, species, strain code)
A probiotic is identified by genus, species, subspecies (if any) and a strain code, for example Lacticaseibacillus rhamnosus GG. Results for one strain do not carry over to another strain [1][2].
Single-strain or multi-strain
Products can contain one strain or many strains of live microorganisms [2].
Capsules, powders and liquids
Probiotic supplements come as capsules, powders, liquids and other forms [2].
Yeast probiotics
Some products use yeasts, such as Saccharomyces boulardii, instead of bacteria [1].
Prebiotics and synbiotics
Prebiotics are nondigestible food parts that feed helpful microbes. Synbiotics combine probiotics and prebiotics [1].
Postbiotics
Preparations of dead or broken-up microorganisms. They are not the same as probiotics [2].
How Probiotics appears on a label
Probiotics are counted in colony-forming units (CFU), the number of live cells. A label may show 1 x 10^9 for 1 billion CFU or 1 x 10^10 for 10 billion CFU [2]. US rules only require the total weight of the microorganisms, which includes dead cells, so the CFU count is voluntary [2]. Look for CFU 'at end of shelf life', not 'at time of manufacture', because cells die over time [2]. Many products have 1 to 10 billion CFU per dose; higher counts are not necessarily more effective [2].
When to take Probiotics
NIH sources do not name a best time of day, and they do not say whether to take probiotics with or without food. In studies on antibiotic-associated diarrhea, probiotics were given along with the antibiotics [1]. Follow the storage directions on the label: some products need refrigeration and others can stay at room temperature [2].
What to keep apart from Probiotics
Antibiotics
Probiotics have been studied alongside antibiotics for antibiotic-associated diarrhea. Which strains, doses and timing work best is still uncertain [1]. Ask your pharmacist how to fit a probiotic around your antibiotic.
Prebiotics (inulin, fructo-oligosaccharides)
Prebiotics are carbohydrates that gut microbes use as fuel. Products that contain both are called synbiotics [2].
Medicines that weaken the immune system
The risk of harm from probiotics is greater in people with weakened immune systems [1]. Ask your doctor or pharmacist first.
Foods that contain Probiotics
- Yogurt with live cultures (some contain probiotic strains)
- Milks, juices, cereals, bars and infant formulas with added probiotics (shown on the label)
Who should ask a doctor or pharmacist first
Talk to a doctor first about probiotics for premature infants, people who are seriously ill or in hospital, and people with weakened immune systems. Severe or fatal infections have been reported in premature infants given probiotics, and the FDA has warned health care providers about this risk [1]. Rare blood infections linked to probiotic bacteria or yeast have mostly involved people who were very ill or immunocompromised [2].
Keep Probiotics in a routine that fits
Supin schedules what you take by time of day, reminds you, and tells you when a bottle runs low.
Probiotics: questions people ask
Probiotics are live microorganisms. Prebiotics are nondigestible food parts that feed helpful microbes. Products that combine both are called synbiotics [1].
There is no official amount. Many products have 1 to 10 billion CFU per dose, but higher counts are not necessarily more effective, and the amount studied depends on the strain [2].
It depends on the product. Some need refrigeration and others can be stored at room temperature, so check the label [2].
Not always. Some probiotic products have been found to contain microorganisms other than those listed on the label [1].
Sources
- Probiotics: Usefulness and Safety — NIH National Center for Complementary and Integrative Health (NCCIH)
- Probiotics: Fact Sheet for Health Professionals — NIH Office of Dietary Supplements
Educational information, not medical advice. The amounts above are official reference values, not a recommendation for you. Check with your doctor or pharmacist before starting or changing supplements, especially if you take medication, are pregnant or have a health condition. Supin sells a subscription, not supplements. Last reviewed .