What is Probiotics

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what is probiotics

What is probiotics?

Probiotics have become incredibly popular over the last few decades. It has become an exciting new field for clinicians, researchers, and most of all – big pharma.

My name is Dr. Tun Min, I am a GP working in Northwest NHS UK. I have a special interest in the field of supplements, fibers, and probiotics relating to Gastrointestinal health.


Scientific definition

The ISAPP, International Scientific Association for Probiotics and Prebiotics defines probiotics as, “Live microorganisms, that when administered in adequate amounts, confer a health benefit on the host”.

What does it mean?

Probiotic comes from the Latin and Greek terms, “ pro “which means “for” and “bios” which means “ life”, together meaning “for life” – which can be defined as live microorganisms which have health benefits on the host. Probiotics are mostly bacteria, but also in the form of fungi and yeast.

In humans, probiotics live almost everywhere, in and outside the body, most abundant in the intestine. 

As we all know, some bacteria are bad, probiotics are mainly bacteria but they live in harmony with our body system and help maintain essential body functions.

How do they work?

Firstly we need to look at the primary function of our intestines

  1. Extracting nutrients from food
  2. Absorbing the nutrients and
  3. Excretion of waste

Probiotic bacteria mainly help with extracting part by digesting and breaking down the nutrients and vitamins making it easier for our gut to absorb.

What are the benefits?

Although probiotics have been popular for decades, it is still considered fairly new to the research field. Some of the benefits have strong research evidence while some of them don’t.

Proven benefits

The main benefits are in gut-related diseases, especially for conditions like, leaky gut, inflammatory bowel disease ( Ulcerative Colitis, Crohn’s), Necrotising Enterocolitis in infants, and Irritable bowel syndrome.

Numerous studies have shown that probiotics help improve the symptoms, such as bloating, indigestion, improved bowel frequency and consistency, and abdominal pain.

It also has reliable research evidence in treating vaginal and urinary infections, such as bacterial vaginosis and UTI.

Needs further evidence

In recent years, there have been findings on something called the gut-brain axis. Basically what it means is, the bacteria in our gut might be releasing neurotransmitters and chemicals to control the function of our brain, affecting mood, stress level, cognition, and general mental health well-being.

Mostly theoretical 

Another interesting fact is related to the immune system and inflammation in the body. Probiotics may help fight infection and regulate immune responses such as in autoimmune conditions.

Since the gut hosts most of our body’s immune cells, providing a good environment in the gut potentially boosts the function of immune cells in our body thus reducing the number of infections. In addition, it is also thought to regulate the immune system and helps in autoimmune conditions.

It is also thought to regulate inflammatory processes in our body, thus some of the companies claiming skin benefits such as eczema, reduce cancer rates, and reduce risks of heart conditions, diabetes, and hypertension but these are quite far away from being proven in research.

Probiotics and research evidence for specific medical conditions

probiotics and research

Gastrointestinal health benefits

Since the body’s natural microbiomes mainly reside>70 % in the digestive tract, the problem with probiotics imbalance mainly occurs as a problem of digestive health, and hence, probiotics supplements play a big role in improving gut health.

Clostridium difficile-associated diarrhea

This is a classic scenario, when patients are given antibiotics, it kills the good bacteria ( probiotics ) and causes the overgrowth of harmful bacteria causing severe infection in the gut.

Although there is conflicting research evidence, this is one of the most commonly prescribed medications in actual clinical practice in the UK, this is pretty common and some NHS hospital guidelines support giving probiotics supplements in this condition.

Inflammatory bowel disease ( Ulcerative colitis, Crohn’s disease)

This is one of the autoimmune diseases of the gut where own immune system cells attack the gut lining causing bleeding and diarrhea.

There is strong research evidence, and meta-analyses have shown that giving probiotics supplements together with standard treatment improves the symptoms, maintains the disease remission longer, and prevents flare-ups

Irritable bowel syndrome ( IBS)

The nature of the disease, if not very well known, is thought to be due to problems with nerves regulating bowel activity.

Another gut condition with very good research evidence, meta-analysis, shows significant improvement in symptoms such as bloating, and flatulence.

Some studies showed improvements in overall symptoms and even quality of life which is quite important since people with IBS often find it very distressing to cope with the symptoms.

Infant colic

This is a fairly common digestive disorder in infants and no proven effective treatment options, which can often make parents very distressed.

The trials on Lactobacillus Reuters showed improvement in symptoms and safe

Infection in the female genital tract

Another place in our body where microbes reside ( mainly Lactobacillus)and help with the function is the female genital parts.

Bacterial vaginosis & candida infection

This is an extremely common infection in females. Combining antibiotics therapy with probiotics supplements has been shown to improve outcomes

Mental health conditions

This is a relatively new finding in the research field of probiotics.

The theory comes from the fact that the microbiomes in the gut might be releasing signals and chemicals controlling brain function, thus probiotics supplements could enhance memory, mental health well-being, and sleep thereby improving overall health benefits.

Allergies, eczema

Although some products advertise beneficial effects in these conditions, there is no sufficient scientific data to prove the claim.

Immune system

  A large proportion of immune cells live in the gut, thus having a well-balanced or more good bacteria in the gut creates a better environment for immune cells to function.

Some of the research has shown to reduce chest infection.

Evidence and further research are still needed and probiotics can be harmful in individuals with a disorder of the immune system or taking medications that can suppress the immune system.

Weight loss

More and more research findings are coming out about the relationship between probiotics and weight loss. Multiple studies have been done on different strains

This relates to the fact that having an optimal gut microbiome environment can optimize gut function and thus have a beneficial effect on weight.

These claims have very little evidence and should not use probiotics for this sole purpose. However, probiotics combined with prebiotics fiber have been shown to have greater health benefits for obesity, regulating blood sugar, and lowering lipid levels.

What are the types/strains/ species of probiotics?

different types of probiotics

Many different specific probiotic strains have been used in research for different medical conditions. Some of them did not show promising results. I have summarised some of the conditions and strains that have been shown to have benefits in specific medical conditions. The link between specific strains and specific diseases is yet to be explored more in research.

Inflammatory bowel disease ( Ulcerative and Crohn’s Disease)

Bifidobacterium breve Lactobacillus acidophilus

Bifidobacterium longum Lactobacillus plantarum

Bifidobacterium infantis Lactobacillus paracasei

Streptococcus thermophillus Lactobacillus bulgaricus

Infant Colic

Lactobacillus reuteri

Bacterial vaginosis

Lactobacillus Species

Saccharomyces boulardii – significant reduction in symptoms for IBS, most trials showed significant efficacy for the treatment of acute pediatric diarrhea

L rhamnosus, a meta-analysis of RCT travelers’ diarrhea

mixture L helveticus, L rhamnosus – strong evidence for eradication of H Pylori

Can I get probiotics from food?

can i get probiotics from food?

Arguably, probiotics could be best consumed in the form of food. Probiotics-rich foods are mainly fermented foods

  • Yogurt
  • Kimchi
  • Miso
  • Kombucha
  • Pickles
  • Kefir
  • Tempeh
  • Natoo
  • Sauerkraut
  • Green olives
  • Some types of cheese

Do I need probiotics supplements?

Generally, if you are a healthy adult, eat as many probiotic-rich foods as possible, and probiotics supplements are not indicated. However, some healthy people like to take probiotics as supplements as they are relatively harmless and there could be unproven benefits.

Storage instruction for probiotics supplements?

It is incredibly important because these are live microorganisms and if not properly stored, will just become powders. Storage options differ on the type of probiotics and the way they are produced. The best advice is “ read the label “ as some of them might need freezing, and some might just need to keep away or keep dry and avoid moisture.

Who should not take probiotics supplements?

who should not take probiotic supplements?

Although probiotics are relatively safe, especially with the available supplement dose, it can also have some side effects.

The best advice for dietary supplements is if you have any medical problem, especially a serious underlying condition, or if you are taking any medications, liaise with a trained healthcare professional.

Caution should be taken for people of extreme age, very young and very old. Probiotics are best avoided if you have severe inflammatory conditions, severe infections, autoimmune conditions, conditions affecting your immune system, or if taking several medications, or medications that can affect your immune system.


Probiotics is an exciting topic in the field of medical research and clinical practice. Although we have found some promising benefits, I believe there is so much more to explore in this already incredibly popular subject. I certainly hope that one day, I can confidently prescribe certain probiotics for specific medical conditions.

Research sources:

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Dr Tun Min is s GP working in NHS UK and writing articles about supplements and vitamins based on personal clinical experience and clinical research.

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