6 Science-Backed Benefits of Probiotics & Who Should Take Them

The Proven Benefits & Effectiveness of Probiotics

What Are Probiotics?

Probiotics are live bacteria and micro-organisms that can provide health benefits when consumed. They were first discovered in 1907 by the Russian scientist Ilya Ilyich Mechnikov who suggested that while some bacteria act as pathogens, most are harmless – and many offer health benefits. He believed that by consuming probiotics- specifically lactic-acid-producing bacteria found in yogurt – we may improve our health and longevity.

Why Do We Need Them

Our bodies are home to between 300–500 different species of bacteria — in total as many as 100 trillion bacteria and microbes that live mainly in our gut. These microbes or microbiota outnumber our own cells and influence much of our health – for better or worse.

As well as helping us digest our food, they make up much of our immune system, help fight infection, regulate our metabolism and even influence our mood and our mental health [1].

We inherit our first doses of probiotic bacteria from our mother through the birth canal when we’re born and subsequently through breast feeding.  This early bacteria is vitally important to our health and provides the foundation of our microbiome – our ecosystem of microbes.  A number of recent studies have found that children born via c-section or fed with formula milk have a different make up of gut bacteria having missed out on these important early strains of probiotics – and as a result are more likely to suffer from allergies, obesity and other health problems in later life. [2]

Our microbiome starts to mature in our early childhood but continues to be enriched and shaped over the course of our lives by the different strains and species we encounter in our environments and from the foods we eat.

However the wrong diet, lifestyle, over-exposure to toxins and pollutants – and also prolonged course of antibiotics – can have a devastating impact on the health and diversity of our gut bacteria and microbes.
Such a disruption puts our gut at risk of dysbiosis, which is where the microbes in our gut become in balanced – a precursor to much more serious chronic condition:

Any significant change or in balance to the makeup of this ecosystem can lead to an overgrowth of all the wrong strains and species including pathogens such as clostridium difficile, candida, and H. pylori which are otherwise kept in check by our good probiotic bacteria.
This can also lead to increased permeability of our gut lining (often referred to as leaky gut) resulting in chronic inflammation and chronic bowel diseases. More serious conditions thought to be caused by an unhealthy balance of gut bacteria include obesity and metabolic diseases such diabetes, bowel cancers, auto-immune diseases ranging from asthma, eczema, allergies and food intolerance to Rheumatoid Arthritis, Parkinsons and MS, – as well as mental health conditions such as depression and anxiety.  

“We know that a more diverse microbiota is correlated with better health”

“We know that a more diverse microbiota is correlated with better health, Patients with inflammatory bowel disease, ulcerative colitis, typically have a lower diversity of microbes in their guts,” according to Dr Longman, a scientist in the Jill Roberts Institute for Research in Inflammatory Bowel Disease and a clinician in the Jill Roberts Centre for Inflammatory Bowel Disease at New York-Presbyterian/Weill Cornell and Weill Cornell Medicine.

How Can Probiotics Help

Taking Probiotics is intended to replace desirable strains and species of bacteria and microbes in our gut to rebalance our biome with good bacteria and microbes – and help increase the diversity of our microbiota.

Probiotics are usually consumed as specific strains contained in supplements or through fermented foods such as live yoghurt, cheeses, sauerkraut and Kimchi. While either method is believed to confer health benefits- under many trials their effectiveness in treating a variety of different ailments has been mixed:

So What Have Probiotics Been Proven to Treat?

While a number of studies on animals have demonstrated their effectiveness in treating a range of diseases, including obesity, diabetes and anxiety, clinical studies to assess their effectiveness in treating a range of diseases in humans have often been inconsistent. This is perhaps not so surprising given that 1) Everyone’s gut bacteria make up is different.
2) Probiotics are not all alike. While a specific strain of Lactobacillus probiotic may treat or prevent a condition, that doesn’t mean another strain of Lactobacillus would have the same effect or that any of the Bifidobacterium probiotics would.3) Different strains of bacteria are understood to behave in different ways providing different benefits. The behaviour of different strains of bacteria can also be affected by the other strains of bacteria present.4) Probiotic supplements need to contain both sufficient quantities and be able to survive the enzymes and acids in the oesophagus, the stomach, and the small intestine to have any effect.5) Lastly when taking probiotics your diet and lifestyle as well as the make-up of your own microbiome and competing bacteria within it, determine the ability of each strain of probiotic bacteria to establish itself, colonize and provide benefit

Antibiotic Associated Diarrhoea – Beneficial   

Some of the strongest evidence of the effectiveness of probiotics can be seen in the treatment of antibiotic-associated diarrhoea. Many patients prescribed antibiotics for an extended period of time suffer from diarrhoea and other digestive problems after the course of the treatment.

Antibiotics can harm the natural balance of our gut microbiome, as – in addition to fighting off the infection they will often wipe out large numbers of good bacteria, allowing other less desirable species present to grow unchecked.

There is strong evidence across a number of different studies to support their effectiveness as a treatment, including a review of 82 Randomized Controlled Trials [3, 4, 5].

Irritable Bowel Syndrome (IBS) – Beneficial

In a review of 37 clinical studies [6],  probiotics were found to be beneficial in treating irritable bowel syndrome (IBS). IBS is an increasingly common, chronic digestive disorder affecting the large intestine with symptoms including stomach cramps, bloating, diarrhoea and constipation. Although there is no cure for the condition, changes in diet and together with certain medications have been found to be helpful in controlling the symptoms. Supplementing probiotics together with a regular well-balanced diet is one such treatment that has been found to help many patients reduce gas, bloating, constipation, diarrhoea and other IBS-related symptoms [7, 8].

Inflammatory Bowel Diseases:

In a review of studies into inflammatory bowel diseases published in 2014 researchers examined 44 different studies of various inflammatory bowel diseases, [9] to assess the effectiveness as a treatment.

Ulcerative colitis – Beneficial

Ulcerative colitis affects the lining of the large intestine. The autoimmune disease produces symptoms such as frequent diarrhea, cramps and abdominal pain and weight loss. In the review of 21 studies of ulcerative colitis published in 2014 [9] probiotics were found to help treat the disease and were most effective once the patient is  brought into remission. The most effective probiotics include Escherichia coli Nissle and VSL#3, a probiotic containing eight strains.

Pouchitis – Beneficial

Pouchitis is another condition involves inflammation of the gut lining of the intestines, often a result of surgery to remove part of the colon in patients with ulcerative colitis. A review of five studies of patients with pouchitis found that probiotics after surgery can help prevent pouchitis.

Crohn’s Disease – No Evidence

While probiotics were found to help treat both Ulcerative Colitis and Pouchitis – the review found did not find sufficient evidence of their efficacy as a treatment of Crohn’s Disease.

Bacterial Infections:

Helicobacter Pylori –Beneficial

A number of studies(10, 11, 12, 13) have found that probiotics can be useful in treating Helicobacter pylori infections – these are known to be the main driver behind conditions such as stomach ulcers and stomach cancer.  

Bacterial Vaginosis – Beneficial

Bacterial Vaginosis – dysbiosis of the vagina and uro-genital tract, is caused by overgrowth of undesirable bacteria and pathogens and a reduction in the healthy lactobacilli probiotic bacteria. The cause is often unknown but can be as a result of antibacterial soaps and shower gels, while treatment with antibiotics often results in a recurring infection.

In a review of studies between 1990 and 2011 probiotics were found to be generally beneficial in both the prevention and treatment of BV [14].

Clostridium Difficile – Beneficial

Clostridium difficile is one of the most common infections to be contracted in hospitals and nursing homes – particularly by patients receiving antibiotics, with a huge rise seen in the last decade.

In individual studies probiotics containing Lactobacillus strains and S. boulardii have been found be effective in the prevention and treatment of Clostridium difficile in high-risk antibiotic recipients. However larger controlled studies are required to confirm these findings.

Candida – Beneficial

Candida is a yeast commonly found in small quantities in our mouth, our skin, our genitals and our gut. In normal circumstances candida is harmless and supports digestion and nutrient absorption – however in an unbalanced microbiome or when the bodies ph is upset, Candida can multiply and lead to UTI and yeast infections, leaky gut and Candida overgrowth syndrome – a chronic health condition.

A number of well-controlled studies and clinical trials have shown probiotics to be beneficial in both preventing and treating Candida infections – in the mouth, the vagina and in the gut.[47]

Probiotics and Obesity

There are clear differences in the makeup of gut flora in overweight or obese people compared with normal lean people (17, 18, 19).  Overweight and obese people tend to have less diversity in their microbiota, as well as higher proportions of Firmicute bacteria compared with Bacteroidetes (the reverse is true in people of a normal, healthy weight).

Our gut microbiota can affect our body weight in a number of ways, such as

• Our metabolism; both the energy we extract from food and also the energy we burn
• The health and permeability of our gut lining and associated inflammation
• Our cravings, as a result of our bodies signals for hunger and satiety [15]

Probiotics are thought to be able help reduce and maintain a healthy body weight by altering our gut microbiota to affect each of these [16]. However it is a hugely complex area that is not yet fully understood and there continues to be much research.

Evidence For the Use of Probiotics for Weight Loss – Inconsistent 

To date most clinical studies examining the effect of probiotics on weight loss in humans have been largely inconsistent.

There is only one significant review that we’re aware of – that has found probiotics to have a significant effect on the weight of the participants.

In a review of 14 randomized control trials published in 2016, a collaboration between French and Israeli researchers Drora, Dickstein, Dubourg and Paul, 14 studies in adults were examined  (9 of the studies included a probiotic dairy food, and 5 of a probiotic single strain supplement).
The authors found probiotics did have a significant bearing on the subsequent weight of the participants, the majority of whom were overweight or obese. The probiotics evaluated included the species Probiotic species included were Lactobacillus acidophilus, L casei, L plantarum, L gasseri, L rhamnosus, . bulgaricus, Bifidobacterium infantis, B lactis, B longum, B breve, Streptococcus thermophilus, and Saccharomyces cerevisiae.

In animal studies however the results are much more exciting, with certain strains of bacteria linked to weight gain and others to weight loss.[26]

Notable studies include research at Washington University School of Medicine in St. Louis where gut bacteria from obese mice were transplanted into the gut of sterile lean mice; who as a result quickly gained weight leading to obesity (19).

In another study where sterile mice received gut microbes from obese and lean humans, the mice that received microbes from obese people gained weight while the mice that received microbes from lean people did not.[27]

If you’re looking for nutritional advice on weight-loss, I would strongly recommend reading NutritionYouCanUse.com, a website that has impartial and very good blog articles on healthy eating.

Probiotics and Diabetes – Beneficial

In a review of 12 studies consisting of 684 patients in Randomized Control Trials the authors found evidence that consuming probiotics may improve glucose metabolism. The analysis, conducted at the Three Gorges University and The First People’s Hospital of Yichang, Yichang, Hubei, China found that taking probiotics was associated with significant improvement in HbA1c (glycated haemoglobin test) and fasting insulin – two important blood tests that provide a good indication of how well diabetes is being controlled in type 2 diabetes patients. [15]

In another study involving Seventy Japanese patients with type 2 diabetes, one group of patients received a fermented drink containing Lactobacillus casei alongside a second control group. After 16 weeks the faeces of both groups were analyzed and showed that the group receiving probiotics had altered the gut microbiota and a reduction in bacteria passing from the gut into the blood stream – thought to be a major cause of inflammation and related health problems. [16]

Probiotics and Skin Health

Probiotics are thought to offer potential benefits in treating a number of skin conditions such as acne, rosacea, eczema, and skin aging.

There are several cosmetic manufacturers who are currently working on adding probiotic strains and extracts to skincare products such as lotions, cleansers and face masks [29].

Acne – Inconclusive

Following some basic clinical trials on both animals and humans, there is evidence to support the use of some oral & topical probiotics for treating of acne [28] however more research is required 

Acne is caused by a number of factors including excessive sebum production,  inflammation, clogged pores as a result of skin follicles that are not shedding properly, aand lastly an overgrowth of the bacterium Propiobacterium acnes (Baquerizo Nole et al., 2014) [28].

Different strains of probiotics have been shown to counter many of these factors, helping to reduce sebum production, reducing inflammation, controlling the growth of Propiobacterium acnes.

Clinical trials examining the effect of probiotic treatments found in a 50% reduction in acne inflammation in one study with the probiotic Enterococcus fecalis (Kang et al., 2009) [28] and a similar reduction in acne count, size and irritation in a second clinical study using higher doses of the probiotic Lactobacillus plantarum (Muizzuddin et al., 2012) [28].

In an Italian study of 40 patients, the probiotics L. acidophilus and Bifidobacterium bifidumas taken orally were found to improve acne (Marchetti et al., 1987) [28]. In another study in a study in Russia, acne patients received oral probiotics in addition to traditional acne therapy and saw a more significant clinical improvement was noted in those receiving the supplement (Volkova et al., 2001) [28]. However the designs of both studies have been criticised making the results are hard to evaluate.

Skin Aging and UV Light – Beneficial

Clinical studies on humans have found oral probiotics to be effective in reducing skin aging as a result of UV light. In one study the probiotic Lactobacillus johnsonii was given to healthy women for 10 weeks, and found to reduce the effects of and increase the cell recovery as a result of UV Radiation (Bouilly-Gauthier et al., 2010) [28].

Eczema – No Evidence 

Eczema is a common skin condition affecting 1 in 5 children in most western countries. The effectiveness of probiotics in treating Eczema or Atopic dermatitis are promising. While there is evidence from a 2016 study [30] to show they can have positive effect in both preventing and treating eczema, there are many factors, including the strain, quantity and the circumstances of each case – and there is still a lack of reliable evidence.

Probiotics and Allergies – Beneficial for Some Allergies

Allergies are a common, hypersensitive immune response to certain substances with symptoms ranging from a runny nose and itchy eyes to more severe rashes, skin irritation and reactions to foods. Probiotics have been found to reduce the symptoms of certain allergies.

Many studies focus on the benefits of L. acidophilus, such as a 2005 study revolving around children who suffered from perennial allergic rhinitis. Child participants were asked to take the probiotic for four months and surprisingly results showed a reduction in nasal swelling (31). A later and similar study was then carried out in 2009 with almost fifty child participants. The results again showed taking probiotics reduced typical allergy symptoms such as a runny nose and nasal blockage (32).

The studies also found that the probiotic was responsible for reducing the amount of the immunoglobulin A antibody in the intestines, this antibody is known to be involved in allergic reactions.

Probiotics and Cardiovascular Health – Beneficial

Researchers have found that probiotics are able to lower bad cholesterol by breaking down bile which is in the gut. Bile is a naturally occurring fluid and is made up of mostly cholesterol and aids in digestion. When probiotics break down bile, it is unable to be reabsorbed into the gut as cholesterol (33, 34).

One meta analyses study found that eating probiotic yogurts for up to eight weeks resulted in a four percent reduction of total cholesterol and a five percent reduction in ‘bad’ LDL cholesterol (35). Another study however did not find any changes in ‘bad’ cholesterol levels, however did note a small increase in ‘good’ LDL cholesterol (36).

Further studies have found that consuming probiotics supplements on a regular basis can help to modestly reduce blood pressure (37, 38). More research is however required within this area.

Summary

The scientific and medical community are all in agreement that there is numerous potential health benefits associated with probiotics – whether through supplement or through foods – and these are generally considered to have low risk. However much more research is required to solidify claims and to fully understand how each strain of probiotic bacteria can benefit or treat each condition.

If you are considering taking probiotic, consult with a doctor or physician familiar with your circumstance. You should also keep in mind that your day to day activities and diet are also just as important in your overall health and wellbeing.