Probiotics Guide - Everything you need to know about taking probiotics
Probiotics Guide - Everything you need to know about taking probiotics

Probiotics Guide – Everything you need to know about taking probiotics


Immediately, people assume that taking a probiotic will fix your gut health “symptoms”, but probiotics are far more than just a simple magic pill – there are many factors that impact the benefits and quality of probiotics. Read on to learn all things probiotics and are they right for you?


Probiotics are live bacteria and yeasts that can be taken in a supplemental form – in a capsule, powder or liquid and vary in their quality, strains and colony-forming units.

Each of us has trillions of bacteria living inside us, with a significant amount of them residing in the gut. Most of these bacteria live harmoniously with us and some even benefit our health. A few strains of bacteria may cause disease or symptoms if left to overgrow. Having a diverse range of bacteria in the gut has been associated with a host of benefits including weight loss, enhanced digestion, improved immune function and a reduced risk of certain diseases.


Probiotics help to restore the natural balance of bacteria in the gut. Due to stress, illness or medication use, the balance of bacteria in the gut may become altered. Probiotics can help to repair this disruption, by reinoculating the gut with more species. 

There is still a great deal of research needed on the microbiome, and whilst probiotics may be helpful for some of us, if you’re looking for a quick fix for your gut problems, it will unlikely be the one solution for you. Working with a gut health specialist is always advised if you have ongoing digestive symptoms.


Probiotics for IBS:

A google of IBS will most likely recommend taking a probiotic, and although probiotics aren’t recognised as a treatment for IBS, a high percentage of people who suffer with IBS, claim that probiotic supplements help to tone down symptoms better than any IBS medication. It’s important to remember that every person is individual and will have different results when it comes to taking probiotics, due to every person’s gut microbes and microbiota being totally unique. 

A recent review demonstrated that the following strains are the most successful strains of probiotic to be taking if you suffer from IBS: (1)

  • Lactobacillus acidophilus
  • Streptococcus thermophilus
  • Bifidobacterium breve
  • Bifidobacterium longum


Probiotics for the Immune system: 

Good bacteria have many vital jobs, one of them being to provide the first line of defence against ingested pathogens, such as bacteria or viruses, preventing bad bacteria from sticking to the gut lining, and strengthening the delicate intestinal wall. Topping up for friendly bacteria with a probiotic supplement can offer an extra level of defence and support, which is invaluable to overall health.

The probiotic Saccharomyces Boulardii is typically used to help with gastrointestinal problems, however, it can also have a strong impact on the immune system. Studies have shown Saccharomyces Boulardii may increase immunoglobulin levels, red and white blood cells such as macrophages, lymphocytes and neutrophils, in addition to being involved in the modulation of immune signalling pathways. (2)

As 70% of our immune system resides in the gut, the probiotic Saccharomyces boulardii combines mechanisms for the gut as well as stimulation of the immune system, it is an important probiotic to be included for immune support. (3)  


Probiotics for skin:

Studies have shown that the use of probiotics in both topical and pill form may help prevent and treat skin conditions such as acne, dry skin, eczema and UV-induced skin damage (4). Certain probiotics have been shown to increase the skin’s production of ceramides that trap moisture in the skin, keeping acne-causing bacteria levels in check. (5)

The following probiotics may have benefits for skin health:

  • Bifidobacterium- may help to reduce skin sensitivity and boost ceramides (6)
  • Lactobacillus- may improve the function of the skin’s barrier to reduce redness and acne (7)
  • Vitreoscilla- may help to reduce water loss and improve eczema  (8)


Probiotics for weight loss:

Obese individuals tend to have a lower diversity of gut bacteria than non-obese individuals. It has also been suggested that those with obesity have less diverse gut bacteria and are more likely to gain weight than those who have a more diverse colony of gut bacteria. (9)

Probiotics have been seen to have an influence on appetite and energy usage via the production of propionate, acetate and butyrate which are all short-chain fatty acids. Certain probiotics may help to inhibit the absorption of dietary fat, increasing the volume of fat excreted through faeces. (10)

These probiotics make your body “harvest” fewer calories from the food being ingested. The probiotic with the most research for weight loss is the Lactobacillus family.  (11)


Probiotics and SIBO:

You may have heard that probiotics and SIBO do not work well together, since SIBO is caused by an excess of bacteria in the small intestine. However, one probiotic, Saccharomyces Boulardii, has been identified as a potentially beneficial strain for SIBO. It may help to protect against inflammation in the gut, and can also help the immune system, by promoting the activity of good bacteria and decreasing the bad microbes that can lead to us feeling unwell. Saccharomyces Boulardii may have the ability to stop pathogens and their toxins from infecting the gut, which can result in inflammation. (12)

Saccharomyces Boulardii has been shown to help patients with SIBO, however, always consult your nutritionist or doctor before starting. 


Spore-based probiotics:

Spore-forming probiotics are actually dormant when ingested, which enhances the survival against the digestive process, causing less uncomfortable symptoms in individuals who struggle with GI symptoms. Once spore-forming probiotics have reached the nutrient-rich environment in the small intestine, they become active. In this active form, they have a long lifecycle and can slowly colonize the GI tract. 

This is perfect for any individuals with SIBO as they leave the small intestine once they have done their job as a probiotic, and are less likely to contribute to any bacterial overgrowth that may be occurring. (13)


How long till they start working?

This depends on a number of factors:

  • The condition you want to target/ support
  • The specific type of bacteria you are taking
  • The quantity and strength of the probiotic you are taking
  • Your own individual body and how it reacts 
  • The state of your gut health at the time of starting

Research has been completed on the following symptoms and treatment with probiotics:  

Bloating: Studies have demonstrated that taking probiotics can aid with gas production and bloating. One study found that it took 21 days to see a reduction in bloating symptoms (14), with another finding symptoms continued to improve up until 8 weeks after they stopped taking the probiotic (15). 

Constipation: When 70 individuals suffering from constipation drank a probiotic-rich beverage for four weeks, they found improvements by the start of the second week. (16)

Diarrhoea: When it comes to acute diarrhoea and probiotics, studies have shown that individuals felt better after taking the probiotic for only two days. (17) 


How do you know if your probiotic is working?

One of the simpler ways to know if a probiotic is working is to keep note of your symptoms over time. For those who do not have symptoms, you may not be able to notice any significant difference. The most accurate way to know is to run an in-depth stool test before and after probiotic supplementation, to see if the quantity and quality of bacteria has changed. 


My top tips for when taking a probiotic include:

-Give it around 7 days for side effects to settle – you may notice an increase in symptoms as your digestive system adjusts

-Low and slow, always start with a lower dosage and work up. If the probiotic dosage is two capsules a day, start with 1 capsule and see how your body reacts before building up to the full dosage. 

-If you’re still suffering from side effects after a week, try a different probiotic and see how your body reacts


Food sources of probiotics:

Some people find that consuming probiotic foods actually have a better impact than taking a supplement. Good, natural food sources to try that are rich in probiotics include:

  • Sauerkraut- buy from the fridge section of the supermarket
  • Kimchi
  • Probiotic yoghurt- ensure to check labels and that it has been fermented with live cultures
  • Kombucha- a great alternative to sugar-filled fizzy drinks  
  • Kefir 


How long should you take a probiotic for?

Research has shown that probiotics don’t “colonise” the gut, therefore we need to take them every day to see and feel an effect. (18) I would suggest starting with a minimum of three months.


Other health benefits of probiotics:

  • Inflammation- probiotics may reduce systemic inflammation, a driver of numerous diseases (19)
  • Depression and anxiety- the strains Lactobacillus helveticus and Bifidobacterium longum have been shown to reduce symptoms of anxiety and depression (20)
  • Cholesterol- A number of probiotics have been shown to lower levels of LDL cholesterol (21)
  • Immune function- Several probiotic strains may help enhance immune function, potentially leading to a reduced risk of infections  (22)
  • Skin- Some research has shown the positive use of probiotics for acne, rosacea and eczema (23)
  • Anti-ageing- There has been some evidence through studies that probiotics may have the potential to extend our lifespan through increasing the ability of cells to replicate themselves, although more research is needed here. (24)

How Many Probiotics To Take?

If you’re taking too many probiotics, you may experience side effects such as bloating, gas and diarrhoea. 

Currently, there is no recommended daily allowance for any type of probiotic strain, however, research has found that taking anything from 1 billion CFU to 10 billion CFU works best as a daily dose. (25)


How to choose the best Probiotic? 

Quantity- I know millions can sound like a lot, but with probiotic supplements, we want doses that contain billions of organisms! Colony-forming units (CFU’s) is the measure used to express the potency of the probiotic, with many brands ranging from 5-100 billion CFUs. Remember to start low and slow and increase as your tolerance goes up. 

Quality- Quality is important when investing in any supplement. A number of commercial brands lack the technology to identify specific strains and the quantity in each strain, which could result in your probiotic being ineffective. With probiotics, it is important to understand whether they survive through the manufacturing process, packaging and branding, shelf life and then when reaching your gut, where they finally get to work. 

I recommend investing in a professional brand (my favourites are listed below) that use thorough testing procedures and have been proven to survive on the shop shelf and also in your gut. 

Diversity of strains– Our digestive systems are unique and diverse, so the probiotic you choose should be too. This can be called a proprietary blend, however be aware that with blends, the transparency of knowing how many CFU each strain contributes is lost. Invest in the one that contains a number of different strains, such as Lactobacillus and Bifidobacterium.

Be aware– Ensure you take a read of the full ingredients, some commercial probiotics can contain excipients such as binders and fillers such as lactose that could cause side effects such as bloating if you’re sensitive to dairy. 



There is a great deal of evidence that presents the positive effects of probiotics for many conditions, especially IBS, bloating, food intolerances, diarrhoea and constipation. Everyone is unique and will react differently to the same probiotic strains, so trial and error is important.

If you suffer from a medical condition, always consult your GP before taking a probiotic supplement. 


am taking on new clients for my GUT HEALTH package- if your gut health symptoms are ongoing, email my team at to find out how I can help 

Clarissa’s favourite probiotics: 


  • Biokult- buy here
  • Bio me barrier- buy here
  • FloraMyces designs for health- buy here
  • VSL3 for IBD and post antibiotics- buy here


References: (1) 

(5) Pais, 2020. Saccharomyces boulardii: What Makes It Tick as Successful Probiotic? J of Fungi. 2020; 6(2), 78 (2)

Stier H, Bischoff SC. Influence of saccharomyces boulardii CNCM I-745 on the gut-associated immune system. Clin Exp Gastroenterol. 2016;9:269-279. doi:10.2147/CEG.S111003 (3) (4) (5) (6) (7) (8) (9) (10)

Bernardeau M, Lehtinen MJ, Forssten SD, Nurminen P. Importance of the gastrointestinal life cycle of Bacillus for probiotic functionality. J Food Sci Technol. 2017;54(8):2570-2584. doi:10.1007/s13197-017-2688-3 (11)

(2) Qamar, 2001. Saccharomyces boulardii stimulates intestinal immunoglobulin A immune response to Clostridium difficile toxin A in mice. Infect Immun. 2001;69(4):2762–2765 (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22) (23) (24) (25)

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Hi there

London Nutritionist Clarissa Lenherr

I’m Clarissa, a registered nutritionist (mBANT) and workplace wellness expert. In my practice, I have helped hundreds of clients reach optimal health through creating sustainable, effective habits and dietary adjustments. My aim is to empower people with the skills, tools and knowledge to take their health into their own hands and feel the happiest, healthiest versions of themselves. Featured in The Daily Mail, Women’s Health, The Telegraph, and more.




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