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All You Need To Know About Probiotics

Updated: Nov 22, 2021

Considering a probiotic supplement? This is the ultimate guide! Discover the benefits, how to choose the right one for you, who might not tolerate probiotics, when to take it and more.


What are probiotics?

Probiotics are the friendly live microorganisms that can in the right amounts have a beneficial effect on our body.

They are mostly bacteria and there are two main types (or genera) that live in the gut, Lactobacillus and Bifidobacterium. Lactobacillus colonizes primarily in the small intestine, while Bifidobacterium colonizes primarily in the large intestine also known as the colon. There are also many different strains and species of probiotic microorganisms. Each offer different health benefits.

Ideally, probiotic supplements should show not only the genus and species but also the strain. For example, Lactobacillis acidophilus UALa-01 indicates the strain "UALa-01", the species "acidophilus" (the strain's immediate family) and the genus "Lactobacillus" (the strain's extended family).


What are the benefits of probiotics?

Probiotics play a role in:

  • Producing certain vitamins and nutrients

  • Enhancing our immunity and reducing our risk of infection

  • Protecting against carcinogens and toxins

  • Discouraging the growth of hostile bacteria

  • Regulating and balancing the gut flora

  • Decreasing inflammation in the intestines

  • Reducing pain sensitivity

  • Digestion

  • Reducing and preventing allergies and sensitivities

  • Soothing the gut and preventing digestive issues

  • Helping with weight management

  • Helping stabilize blood sugars

  • Improving mood


As mentioned, each strain can offer different benefits. When choosing a probiotic supplement this should be taken into account. A quick pubmed search for research on a particular health concern and a beneficial probiotic can help.

For example, the strains L. acidophilus DDS-1, L. bulgaricus and Streptococcus thermophilus may potentially help those with lactose intolerance.

L. reuteri NCIMB 30242 (LRC) has been shown to support heart health.

For weight management L. gasseri BNR17 may help.

For allergy and hayfever support L. rhamnosus GG is usually recommended.

Irritable bowel syndrome sufferers may find L.acidophilus, L. plantarum 299v, or B. breve may offer some relief.


However, it's important to point out that some studies use multiple strains making it difficult to determine if multiple strains are needed to see a benefit or if just one strain provided the most benefit. Also, just like one drug may work for one individual but not for another, the same can occur with probiotics. It can be trial and error.


Improving gastrointestinal symptoms is a common benefit of Lactobacillus and Bifidobacterium probiotics. Studies have shown people with irritable bowel syndrome (IBS) appear to have fewer Lactobacillus and Bifidobacterium bacteria but more potentially harmful Clostridium, Streptococcus, and Escherichia coli.

Though, not all species or strains of Clostridium, Streptococcus and E. coli are harmful. Sometimes it also depends on the quantity present. An overgrowth of even beneficial strains can cause issues. For example, Escherichia Coli is involved in the production of vitamin K2, necessary for blood clotting. But overpopulation of even the good type of E. Coli can put you at risk of the infectious type that can cause vomiting and diarrhea. It has been suggested that this is because overpopulation of even the good type can cause the immune system to struggle to identify and act quickly against the infectious form.


So, what is the best probiotic?

Since every individual's microbiome and needs are different, choosing a broad-spectrum probiotic with a large number of strains is recommended, unless you want targeted support for a particular health concern. A broad-spectrum probiotic widens the variety of good microbes in your gut. To further broaden your exposure it is recommended that you change brands and types regularly.


What else needs to be considered when purchasing a probiotic? Are refrigerated ones better? How about spore-based probiotics?

Certain probiotic species require refrigeration to maintain a good therapeutic number of microbes. These are usually lactic acid-based lactobacilli and/or bifidobacteria as they tend to die above a certain temperature.

A probiotic supplement should list the number of Colony Forming Units (CFUs). This indicates the number of microbes present, which should be in the billions. High-quality probiotics would have had the CFUs tested after exposure to higher temperatures for a number of days. The CFUs listed should be the minimum present after such exposure.


Probiotics are not always bacteria. For example, Saccharomyces boulardii is a gut-friendly yeast that functions as a probiotic and has some amazing benefits.

It has been shown to:

  • enhance immune function in the gut

  • protect the intestinal lining from harmful bacteria

  • aid digestive enzymes for nutrient absorption and digestion

  • prevent and treat antibiotic-associated, infectious and functional diarrhea

  • helps preserve and/or restore the function of the intestinal barrier (prevent a "leaky gut")

  • help maintain a healthy balance of good and bad microorganisms

Some probiotic strains stick around in the gut better than others.

Most do a job, then leave, so long term supplementation of some strains may be necessary. Though, encouraging the growth of friendly bacteria with prebiotics and dietary fibre can help. S. boulardii, for example, settle in the gut over about three days but will be absent from the system within roughly five days.


Soil or Spore-based probiotics Soil-based organisms (SBO) are bacteria (and other life forms) that live in the soil. They provide benefit to plants just like probiotics do to humans. They break down plant material, produce vitamins, and combat pathogens. SBOs are spores that come from the ground and are not naturally found in the body. But we consume them when we eat plants and plant-eating livestock.

We used to consume a lot more of them, but they were always meant to be transient visitors to our microbiome, so there is debate over their benefits as a supplement. Some recommend SBOs over standard probiotics because they can better withstand temperatures and are not as sensitive to stomach acid. But ultimately, we must recognise that SBOs offer different benefits to those probiotics that occur naturally in the body. Some may find them beneficial, some may not. For reference, most common strains of SBOs come from the Bacillus genus. This includes Bacillus indices, subtitlis, coagulans, clausii and licheniformis.


Can some people NOT tolerate probiotics?

Yes, unfortunately, some can't! Those with a small intestinal bacterial overgrowth (aka SIBO) may not tolerate probiotics or even fermented foods and drinks because their gut is already overloaded with micro-organisms. They first need to address the bacterial overgrowth, heal the gut, and improve gut motility, before moving on to probiotic supplementation. It is suggested they introduce fermented foods and/or a probiotic supplement very slowly, starting with low doses.

Dairy and D-lactate free?

For those that have problems consuming dairy, certain probiotic supplements may not be ideal. If you're unsure if dairy is an issue for you, then it is recommended you look for a multi-strain probiotic that states it is dairy-free.


Certain species of probiotics and fermented foods can cause a release of D-lactate (or D-lactic acid). An accumulation of lactic acid is rare but for those with short bowel syndrome, it can be damaging and dangerous. Some probiotics, therefore, indicate if they are D-lactate free. Those with autism may also do better on D-lactate free probiotics.

Histamine intolerance

Some bacteria in the gut can work to manufacture a lot of histamine while other probiotic species restrain histamine synthesis. For those with allergies and who struggle to break down histamine this needs to be considered when selecting a probiotic. Lactobacillus casei, Lactobacillus bulgaricus, and Lactobacillus rheuteri may increase histamine levels, and make symptoms worse. Lactobacillus rhamnosus, Bifidobacterium infantis and Bifidobacterium longum may help lower histamine in the body.

Keep in mind, fermented foods and drinks can also increase histamine levels. A reaction is entirely dose-dependent and will only occur once a certain threshold is reached.

When should I take my probiotic?

There is debate on when is the best time to take probiotics. Many recommend on waking, at least 30 minutes before breakfast in the morning. Others just before bed. This is apparently when the stomach's gastric acidity is naturally at pH 4 or above, as an important factor in a high-quality probiotic is its ability to survive through gastric acidity and reach the intestines.


However if the probiotic is of superior quality (typically practitioner only ranges), the timing shouldn't have an impact, as its ability to survive against stomach acids and bile salts should have been adequately tested.


Spore based probiotics are a little different. They should be taken with a meal.

What are food sources of probiotics?

These include fermented foods or beverages such as kefir, sauerkraut, kombucha, miso, tempeh and kimchee. There are numerous recipes online on how to make these products as they can be expensive if store-bought. Slowly incorporating them into your diet is a great way to increase your sources of beneficial probiotics.

Can I just eat yoghurt?

Yoghurt usually contains only a couple of strains of beneficial bacteria. (If you choose the right one). Typically they are the lactobacillus and bifidobacterium strains. However, most yoghurt is not health food, but laden with sugar and chemicals. Real yoghurt simply contains cultures and full-fat cream/milk. So it is best to choose high-quality unsweetened brands or make your own. Kefir (said Ki-fear) is a pourable probiotic yoghurt which contains many more beneficial strains than standard yoghurt. Why not give it a go?

What are prebiotics?

Often confused with probiotics are prebiotics. Prebiotics are nutritional compounds, particularly fibre, used to promote the growth of beneficial microbes and thus also have the potential to improve gastrointestinal health. It is therefore important to have adequate fibre intake to improve the ability of the probiotics to hang around and do their job. Some great prebiotic foods include cooked or raw onion, raw asparagus, raw leeks, raw garlic and under-ripe bananas. Psyllium husk and acacia gum powders also offer beneficial soluble fibre and can also be added to smoothies and used as a prebiotic.

Including probiotic foods or a supplement in your diet daily is an important way to stay healthy in our frequently toxic environments. As you've learnt, there are so many amazing benefits, from improved immunity, digestion, mood and even lowered disease risk. As Hippocrates once said, "ALL DISEASE BEGINS IN THE GUT". So, please do not ignore or underestimate the benefits a healthy gut can have on your life.

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