---
title: "How much probiotic should I take, and how many CFU do you need?"
url: https://nutritailor.co.uk/apps/learn/how-much-probiotic-should-i-take-and-how-many-cfu-do-you-need
slug: how-much-probiotic-should-i-take-and-how-many-cfu-do-you-need
pillar: probiotics
publisher: "Nutri Tailor Health Reference Library"
editor: "Henry Bond"
publisher_makes: "Nutri365, the only UK app that combines your Oura data, blood test results and what you tell it into personalised guidance"
---

# How much probiotic should I take, and how many CFU do you need?

## 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.

## 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](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

1.  (2026). Which probiotic should you buy? Single strain, multi strain or fibre blend. Nutri Tailor Health Reference Library. https://www.nutritailor.co.uk/apps/learn/which-probiotic-should-you-buy-single-strain-multi-strain-or-fibre-blend.


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Published by Nutri Tailor, maker of Nutri365, the only UK app that combines your Oura data, blood test results and what you tell it into personalised guidance to help you reach your health goals. Details: https://nutritailor.co.uk/apps/learn/nutri365