15% off £25 or 20% off £35
Code:BASKET
Good bacteria, better benefits: probiotics explained
Written byMedico Digital
Reviewed byProfessor Laurence Lovat
Behind the trend lies a simple idea: adding more of the ‘good bacteria’ your gut loves. We asked Professor Laurence Lovat, consultant gastroenterologist, to share how probiotics really work — and why
Summary
1What are probiotics?
Probiotics contain certain strains of ‘good’ bacteria and yeasts. They can be taken as daily supplements or enjoyed in foods like…
2How do probiotics work?
Probiotics are thought to work by encouraging the growth of ‘good’ bacteria in our bodies, which in turn help stop ‘bad’ bacteria from growing and…
3What are probiotics good for?
Probiotics may help restore gut balance after it’s been disrupted by things like illness or infection, supporting digestion...
Bacteria often get a bad rap, but they’re actually important for keeping your body healthy.1 In fact, your body hosts between 500–1000 different species of bacteria at any one time (not to mention the viruses and fungi tagging along).1
It might sound scary, but this collection of ‘good’ bacteria, viruses and fungi is known as your microbiome – and it’s actually a good thing.1,2
Found in places like your skin, gut and mouth, your microbiome assists your immune system, supports your gut health and helps keep everything running smoothly.1,2 But if the balance of microbes gets disrupted, it can lead to a whole host of problems.2
That’s where probiotics may help. Packed with beneficial strains of bacteria and yeasts, they may potentially support your gut microbiome and overall health.3
To unpack this further, we asked consultant gastroenterologist Dr Lovat for his expert thoughts on what probiotics really do, how they work, if they have any benefits and whether they live up to the hype.
What are probiotics?
Probiotics are certain strains of ‘good’ bacteria and yeasts.4 They can be taken as daily supplements or enjoyed in foods like yoghurt.4
Probiotics are thought to offer various potential benefits, such as helping restore gut balance after illness or infection and supporting digestive comfort, although evidence for many health claims remains limited.4
Since they’re classed as food supplements, probiotics don’t have to undergo the same strict testing as medication.4 This means that we don’t always know how effective a particular product really is, if it contains the specific bacteria strain it claims or if those bacteria will even make it to the right part of the body.4
With so many different probiotics available, each containing a variety of microorganisms, they can have unique effects on the body.4 Let’s take a closer look at some of the most common ones.
Types of probiotics
Probiotics are identified by the name of the specific bacteria or yeast strain they contain.5
Some of the most common species include:5
- Lactobacillus
- Bifidobacterium
- Saccharomyces
- Streptococcus
- Enterococcus
- Escherichia
- Bacillus
Only specific strains of bacteria that have demonstrated potential health benefits are recognised as probiotics.5
So, how do these ‘good’ strains of bacteria and fungi help keep your body healthy?
How do probiotics work?
Probiotics are thought to work by encouraging the growth of ‘good’ bacteria in our bodies, which in turn help stop ‘bad’ bacteria from growing and causing diseases.3,6
Think of your body like a car park: when spaces are filled with ‘good’ bacteria, there’s no room for the harmful ‘bad’ bacteria to park and cause trouble.
Certain specific probiotic strains have been studied for their potential to support the immune system, though findings differ and the exact ways they may work are not yet fully understood. Other strains of probiotics may also have properties that make them useful for specific areas of health, especially when it comes to digestive health.3,5,7,8
What are probiotics good for?
Before we get into the potential benefits of probiotics, it’s important to realise that not all health claims surrounding them are backed up with strong, high-quality evidence.4,9 The results also vary depending on the type of probiotic.4,9
So, you may be left wondering: should I take probiotics? That’s totally up to you. The NHS advises that probiotics are generally safe for most people with healthy immune systems, but if you have any underlying health conditions (especially ones that affect your immune system), it’s a good idea to check with your doctor first.4
If you decide to give probiotics a try, how long will they take to work? That really depends on the type of probiotic you’re taking, its strength and what you’re hoping to achieve.3,5-10
If you’re focusing on supporting your digestion, the NHS and BDA (British Dietetic Association) suggest trying a probiotic for at least four weeks to see if it works for you.11,12 If they don’t work, try another type or stop taking them – they won’t work for everybody.12
Probiotic supplements are one way to go. They can contain a single strain or a blend of several different types, so it’s worth doing a bit of research to find the best option for your needs.3,8
Alternatively, you can support your gut health naturally with probiotic-rich foods.3,5
Probiotic foods: natural sources of probiotics
Fermented foods are a great natural source of probiotics.3,5 Stick to foods that haven’t been processed after fermentation to get the highest concentration of live cultures.5
Yoghurt is a popular choice for probiotics, but there are plenty of other fermented foods that may contain probiotics, including:5,13
- some cheeses
- kimchi or sauerkraut (fermented cabbage)
- kombucha (fermented tea)
- miso (fermented soybean-based paste)
- some pickles
- raw, unfiltered apple cider vinegar
- kefir
- tempeh
Adding some of these foods to your diet can give you a natural dose of probiotics.5
The final say
While more research is still needed, some specific strains in probiotics have been found to have a potential benefit in gut health and immune response.3-5,10
They’re generally safe for most healthy people, but it’s always a good idea to do your own research before trying any supplement and speak to your GP for advice if you have any underlying health conditions.3
We’ve talked about probiotics, but have you heard about prebiotics? Learn more in our guide to prebiotics, probiotics and postbiotics.
Disclaimer - The advice in this article is for information only and should not replace medical care. Please check with your GP or healthcare professional before trying any supplements, treatments or remedies. Food supplements must not be used as a substitute for a varied and balanced diet and a healthy lifestyle.
While we strive for accuracy and balance, please be aware that this article may discuss products available for purchase through Holland & Barrett. Consult a healthcare professional before making any health-related decisions.
1. Gilbert JA, et al. Current understanding of the human microbiome. Nature Medicine. 2020;24(4):392–400. https://pmc.ncbi.nlm.nih.gov/articles/PMC7043356/
2. Hou K, et al. Microbiota in health and diseases. Signal Transduct Target Ther. 2022;7(1):135. https://doi.org/10.1038/s41392-022-00974-4
3. Bodke H, Jogdand S. Role of probiotics in human health. Cureus. 2022;14(11):e31313. https://doi.org/10.7759/cureus.31313
4. NHS. Probiotics [Internet]. [cited 2025 Feb 25]. Available from: https://www.nhs.uk/conditions/probiotics/
5. NIH. Office of Dietary Supplements - Probiotics [Internet]. [cited 2025 Feb 25]. Available from: https://ods.od.nih.gov/factsheets/Probiotics-HealthProfessional
6. Mazziotta C, et al. Probiotics mechanism of action on immune cells and beneficial effects on human health. Cells. 2023;12(1):184. https://doi.org/10.3390/cells12010184
7. Varela-Trinidad GU, et al. Probiotics: Protecting our health from the gut. Microorganisms. 2022;10(7):1428. https://doi.org/10.3390/microorganisms10071428
8. Cunningham M, et al. Applying probiotics and prebiotics in new delivery formats – is the clinical evidence transferable? Trends Food Sci Technol. 2021;112:495–506. https://doi.org/10.1016/j.tifs.2021.04.009
9. Brüssow H. Probiotics and prebiotics in clinical tests: An update. F1000Res. 2019;8:1157. https://doi.org/10.12688/f1000research.19043.1
10. Kristensen NB, et al. Alterations in fecal microbiota composition by probiotic supplementation in healthy adults: a systematic review of randomized controlled trials. Genome Medicine. 2016;8(1):52. https://doi.org/10.1186/s13073-016-0300-5
11. NHS. Good foods to help your digestion [Internet]. [cited 2025 Feb 25]. Available from: https://www.nhs.uk/live-well/eat-well/digestive-health/good-foods-to-help-your-digestion
12. British Dietetic Association. Probiotics and gut health [Internet]. [cited 2025 Apr 3]. Available from: https://www.bda.uk.com/resource/probiotics.html
13. Azizi NF, et al. Kefir and its biological activities. Foods. 2021;10(6):1210. https://doi.org/10.3390/foods10061210
