Health Reference LibraryHow much probiotic should I take, and how many CFU do you need?
This entry is part of the Nutri Tailor Health Reference Library — cited research on supplements, nutrients and adjacent areas of health.
Summary
One to ten billion CFU a day of a named strain, taken daily for four to eight weeks, is what most of the trials used and is enough; the strain and the daily habit matter more than the count, and a well studied strain at 4 billion beats an unnamed blend at 50 billion. Probiotics are live bacteria rather than nutrients, so there is no reference intake and no upper limit, and counts above 20 billion have not been shown to do more. Wind in the first week is normal and settles. Anyone with a suppressed immune system asks their GP first.
Dose calculator: capsules to reach your probiotics target
Enter the daily amount of probiotics you are aiming for and see how many servings of each Nutri Tailor product reach it. Nothing you enter leaves this device. No AI is used.
This tool does arithmetic on the label figures. It is not personal dosing advice and it knows nothing about your history or blood results. The reference intake, the safe upper guide and the trial doses are on this page; talk to your GP or a registered nutritional therapist before changing what you take.
Effective dose
The reference intake is none; probiotics are live bacteria, not nutrients, and are measured in colony forming units (CFU) rather than milligrams. Most of the trials for bloating, bowel habit and recovery after a disruption used between 1 and 10 billion CFU a day of a named strain, taken daily for four to eight weeks. The strain and the daily habit matter more than the count: a well studied strain at 4 billion beats an unnamed blend at 50 billion. Take it daily at the same time, with or just before a meal, and judge it after a month.
Safety profile
How much is too much: no upper limit; the trials used 1 to 20 billion CFU a day, and more than that has not been shown to do more. Probiotics are safe for almost everyone; wind and mild bloating in the first week are common and settle. The people who should not take them without their GP are those whose immune system is suppressed, anyone who is seriously ill, and people with a central line. Very high counts add cost and, in some products, sweeteners and fillers, not effect.
Guideline positions
NHS vitamins and minerals guidance for probiotics. NIH Office of Dietary Supplements fact sheet for probiotics where one exists. The trial doses quoted above are from the sources listed on this page.
Practical framework
Capsules to reach the dose, from the Nutri Tailor range, all made in the UK: [Combocillus multi strain capsules](/products/combocillus), about 4 billion CFU per capsule across seven named strains, one a day; [Lactobacillus rhamnosus powder](/products/lactobacillus-rhamnosus), 5 billion CFU per 500 mg scoop of a single named strain. To read your own result against the UK ranges, use the free blood test result interpreter. This is a summary of published research, not personal health advice. Talk to your GP or a registered nutritional therapist before changing what you take, especially if you are pregnant, have a diagnosed condition or are under ongoing care.
Common misconceptions
That more probiotics works faster: above the doses the trials used there is no extra effect, only more side effects. That the front of the bottle states the dose: read the per capsule figure and the serving size on the back. That the NHS figure is a toxic threshold: it is the level below which harm is unlikely, which is a different thing.
Sources
- 2026. Which probiotic should you buy? Single strain, multi strain or fibre blend. Nutri Tailor Health Reference Library.