The World Health Organization and the FAO defined probiotics in 2001 as live microorganisms which, when administered in adequate amounts, confer a health benefit on the host. Every word in that sentence is doing something: live, adequate amount, and a benefit that has been shown for that organism. A product earns the name by meeting all three, not by printing it on a sachet.
Genus, species, strain
Bacteria are named in three parts. Lactobacillus is a genus. Lactobacillus rhamnosus is a species. Lactobacillus rhamnosus GG is a strain — a specific, catalogued organism, and the level at which research is done and benefits are shown. Two strains of the same species can behave quite differently in the gut. A label that stops at the species ('Lactobacillus acidophilus') is telling you less than one that names the strain, and a label that just says 'probiotic blend' is telling you almost nothing.
Some names you will see on Indian labels: Lactobacillus rhamnosus GG, one of the most studied strains in children; Saccharomyces boulardii, which is a yeast rather than a bacterium and is therefore unaffected by antibacterial antibiotics; Bifidobacterium longum, a common resident of the infant gut; and Bacillus coagulans (often labelled by its older name, Lactobacillus sporogenes), a spore-former that survives heat and stomach acid well.
What CFU means, and when it is counted
CFU stands for colony-forming units: the number of live organisms in a dose, measured by how many colonies grow when a sample is cultured. Five billion CFU is written 5 × 10⁹. The number to ask about is when it was counted. Organisms die slowly in the pack, faster in heat, so a count 'at time of manufacture' can be far higher than what is left when you open it. A count guaranteed 'at end of shelf life' or 'until expiry' is the honest figure, and it is why the storage instruction on a probiotic pack is not decoration.
Prebiotic, probiotic, synbiotic
A prebiotic is not an organism at all; it is a substrate — typically a fibre such as fructo-oligosaccharide or inulin — that the beneficial bacteria feed on. A probiotic is the organism. A product that combines the two is sometimes called a synbiotic, on the logic that arriving bacteria establish more readily when their food arrives with them. Bovine colostrum, the first milk a cow produces after calving, is used in some Indian formulations in this supporting role: it is rich in immunoglobulins and growth factors and is thought to help the introduced strains settle. It is a non-vegetarian ingredient, which the pack has to declare with the brown non-vegetarian symbol.
Taking it with antibiotics
Probiotics are most often bought during or just after a course of antibiotics. The practical rule is spacing: take the probiotic at least two hours away from the antibiotic dose, so that the antibiotic has been absorbed before the bacteria arrive. Saccharomyces boulardii, being a yeast, is not affected by antibacterial antibiotics and can be taken alongside them. Continue the probiotic for a week or two after the antibiotic course finishes, which is when the gut is repopulating.
Who should ask first
Probiotics are food-grade organisms and are well tolerated by most people, but they are live organisms. Anyone with a seriously weakened immune system, anyone with a central line or recent major surgery, premature infants, and infants under a year should not be given a probiotic without a doctor's say-so. For everyone else, the questions to settle are the same ones as for any supplement: which strains, how many CFU at expiry, and how to store it.
Sources
- 1.FAO/WHO. Health and Nutritional Properties of Probiotics in Food including Powder Milk with Live Lactic Acid Bacteria. Expert consultation report, 2001
- 2.Hill C et al. The International Scientific Association for Probiotics and Prebiotics consensus statement on the scope and appropriate use of the term probiotic. Nat Rev Gastroenterol Hepatol, 2014
- 3.Food Safety and Standards (Health Supplements, Nutraceuticals, Food for Special Dietary Use, Food for Special Medical Purpose, and Prebiotic and Probiotic Food) Regulations, 2022 — FSSAI
General nutrition information, not medical advice. Nutraceuticals are not intended to diagnose, treat, cure or prevent any disease. Speak to your doctor before starting a supplement if you are pregnant, breastfeeding, on medication or managing a condition.