The Health Benefits of Probiotics

health benefits of probiotics

Eli Metchnikoff was the first to identify the beneficial role of the bacteria in the gastrointestinal tract of humans, and he received the Nobel prize in 1908 for it. He observed that primarily in Balkan farmers who consumed cultured, fermented milk in their diet lived longer. Then he came up with the theory of longevity, which correlates with prolonged youth and healthy old age. Since then, we know much more about this field. The bacteria in humans’ bodies outnumber the number of cells to 10 to 1, which means one can have up to 30-300 trillion bacteria living inside the gut. The majority of these are pretty harmless, and some are very helpful for the human body. These microorganisms live in symbiosis in the human body; the human body provides food for the bacteria, and in exchange, it receives a lot of health benefits. The community of microorganisms in the human gut is called gut microflora, gut microbiome, or gut microbiota. The latter includes bacteria, viruses, fungi, archaea, and helminths, but most of them are bacteria. There are approximately 300-500 different types of bacteria species living in this ecosystem. Most of the gut microflora colonizes the colon or the large intestine of the digestive tract.

A healthy gut microflora is linked to numerous health benefits, including weight loss, improved digestion, healthier skin, enhanced immune function, and reduced risk of some diseases. Probiotics are a particular type of friendly bacteria, provide health benefits when eaten. Many people take probiotics as supplements, although many fermented food products contain probiotics. These can help to colonize the human gut with good microorganisms. However, there are still many mysteries in the field of probiotics and their relation to human health. This article will describe the health benefits of probiotics and what we currently know about gut bacteria. The metabolic activities of the gut microflora show similarities to an organ, therefore according to some scientists, we should take care of it like if it was our liver or kidney.

Probiotics and their importance to Human Health

Probiotics are living microorganisms, bacteria, or fungi that can reach the gut after ingested. These organisms play a vital role in many bodily functions; therefore, eating the right type can positively affect health. However, there is no scientific consensus about which bacteria strains are the healthiest ones. Some claims are unsubstantiated, while others are waiting for evidence. Probiotics are usually bacteria, but certain types of yeasts (fungi) can also act as probiotics. The most common types of probiotic bacteria are genus Lactobacillus and Bifidobacteria. Others might be Saccharomyces, Streptococcus, Escherichia, Enterococcus, and Bacillus. Each of these genus consists of different species, and each species has many different strains.

The gut microflora carries out many different vital health functions. For example, it manufactures vitamins, such as vitamin K and some B vitamins, most notably vitamin B12. A lack of the latter causes neurodegeneration; therefore, a healthy gut microflora is essential in preventing this deficiency. Gut bacteria can also turn fiber into healthy short-chain fatty acids, such as butyrate, propionate, and acetate. These are crucial components that feed and strengthen the gut wall and perform various metabolic functions. These fatty acids also stimulate the immune system by preventing unwanted substances from entering your body and provoking an immune response.

The human microbiome is very responsive to diet. Studies show that an unbalanced gut microflora is associated with many diseases. For instance, an unhealthy gut microbiome increases the risk of obesity, type 2 diabetes, heart disease, metabolic syndrome, Alzheimer’s, colorectal cancer, and even depression. Probiotics and prebiotics can help fix the balance in the gut and aid in the proper functioning of beneficial bacteria.

Food rich in Probiotics


Probiotics are available in two forms: supplements and fermented food products such as yogurt, sauerkraut, tempeh, kimchi, and kefir. The last one can be very quickly produced at home using the right strain, sugar, water, and fruit. The kefir microorganisms disintegrate the sugar in a day or two, and the product is last acid, very low (below 1%) alcohol, carbonic acid, and most importantly, beneficial bacteria and fungi.

Probiotics are identified by their specific strain on the labels of the supplements, including the species, subspecies, and a letter-number strain code. It is essential because different probiotics can improve various health conditions, thus choosing the right type of probiotics is critical. Broad-spectrum probiotics or multi-probiotics mixed with other species in the same product can induce a wide range of health problems. The evidence is very promising so far, and future studies will shed more light on this field.

The difference between probiotics and prebiotics

Probiotics are different from prebiotics. The latter are carbs, often dietary fibers, that feed healthy gut bacteria. Prebiotics, such as inulin and pectin, exhibit several health benefits, including preventing and improving diarrhea, relief from inflammation and other symptoms associated with an intestinal bowel disorder, and protective effects to prevent colon cancer. Prebiotics can also enhance minerals’ bioavailability and uptake and reduce some cardiovascular risk factors. They also promote satiety and weight loss, helping prevent obesity.

Products that contain both prebiotics and probiotics are called synbiotics. Synbiotic products homogenize friendly, healthy bacteria with some medium for the bacteria to eat, essentially prebiotics. The combination of prebiotics and probiotics generates a synergic effect because both can inhibit the growth of pathogenic bacteria and enhance the growth of beneficial microorganisms. According to a study, synbiotic therapy consisting of Bifidobacterium longum and psyllium was superior to any of these when applied alone in improving inflammatory bowel disease (IBD) questionnaire scores and C-reactive protein (CRP) levels.

 Health benefits of probiotics

Building a healthy ecosystem of gut bacteria can have many positive effects on the body, and some of these are well-documented. The most important benefits may be preventing diarrhea, constipation, reducing inflammation, changes in bile salt conjugation, and enhancement of antibacterial activity. Moreover, they can contribute to the synthesis of vitamins and other nutrients and improve their bioavailability. Probiotics can also alleviate the symptoms of allergy, cancer, respiratory and urinary tract infections. But there are also reports on beneficial effects on aging, fatigue, osteoporosis, obesity, and type 2 diabetes. It is challenging to modify the gut microflora, and it does not happen overnight. Most of the beneficial effects manifest themselves after 8-12 weeks. Let’s dig deeper into the health effects of probiotics.

Positive impact on digestive health

probiotics for digestive health

Probiotics are the main focus of research on digestive health. According to the evidence of studies, probiotic supplements can promote the regeneration of healthy bacteria after antibiotic treatment. This effect can alleviate the symptoms of gut bacteria imbalance, such as diarrhea. Antibiotics destroy bacteria that cause infections, but they also harm healthy ones. This unintended effect can lead to diarrhea even long after eradicating the infection. Probiotics can also help fight the symptoms of irritable bowel syndrome (IBS), a common digestive disorder that causes gas, abdominal pain, bloating, constipation, and diarrhea. Current studies indicate that multi-strain probiotic supplements can improve the status of people with IBS, especially when taken for longer than eight weeks.

However, there are still a lot of questions yet to be answered, such as which probiotics, or probiotic mixtures, are most effective and whether different types of IBS require specific probiotic treatments or not. Additional large trials are needed to figure these out before doctors can prescribe probiotic treatments consistently for IBS. Some studies also demonstrate the benefits of probiotic supplementation to combat inflammatory bowel diseases, such as ulcerative colitis and Crohn’s disease. Moreover, regular probiotic consumption may also help fight Helicobacter pylori. The condition is the primary cause of ulcers and stomach cancer.

Impact on weight loss

weight loss

Losing weight is not only diet and exercise, but current research on gut bacteria also suggests. Some studies indicate that people who are obese have different gut bacteria than lean people. This observation holds for both children and adults. Changes in gut bacteria can cause obesity and act as a co-factor for losing weight. There are specific probiotic strains that can aid weight loss. Lactobacillus gasseri is one of the most studied strains for its beneficial effects on losing weight. According to a study, daily consumption of the probiotic Lactobacillus gasseri can target excess belly fat. Scientists notice positive results already after 12 weeks. Lactobacillus rhamnosus and Bifidobacterium lactis can also help lose weight and help prevent obesity, but this research is limited so far.

However, researchers advise caution in rushing to this conclusion, noting that there are still many unknown facts, such as the specific strains of probiotics used and what dosage. Moreover, it is also unclear what the duration of the treatment is, the long-term effects, and how it interacts with age, gender, health conditions, and lifestyle.

Probiotics may help with neurodegenerative diseases

In the last few years, fascinating research has shown that the gut and brain are interlinked in a gut-brain axis system. This axis connects the body’s central and enteric nervous systems. The study has demonstrated that particular microbes in the gut can affect the brain via this axis in both health and disease. Therefore, by impacting the gut, one may indirectly impact brain function as well. These bacteria are the focus of an emerging field called psychobiotics.

Research indicates that the specific strains of probiotics called psychobiotics can help treat cognitive and neurological disorders. These diseases have more common than you think; individuals who have autism, Alzheimer’s disease, and Parkinson’s disease, especially when they age. The current research focuses on which microbes can function as psychobiotics and how they can affect the brain. Some researchers suggest that people who currently take certain psychotropic medications for mental stress could change it to probiotics. They can bring the same benefits without the undesired side effects of the pharmaceutical drugs.

Inflammation Reduction

Probiotics can reduce systemic inflammation, which is a leading underlying cause and symptom of many diseases. This way, it could improve the status of patients with ulcerative colitis, Crohn’s disease, and rheumatoid arthritis.

Depression and anxiety

Research has shown that some probiotic strains, such as Lactobacillus helveticus and Bifidobacterium longum can reduce anxiety and clinical depression symptoms. Gut bacteria may play an essential role in producing particular hormones responsible for regulating mood. Suppose the wrong type of bacteria is present in your gut. In that case, this could induce specific hormones resulting in a chemical imbalance leading to mood swings, lethargy, and depression.

Lower blood cholesterol levels

Studies also showed that several probiotics could lower the total and LDL cholesterol levels, which is beneficial for the body. This effect mechanism is not entirely clear yet, and there is also research that disproves this finding.

Lower blood pressure 

Usual consumption of probiotics may lead to modest reductions in blood pressure, which is particularly relevant for preventing cardiovascular diseases, a leading cause of death in Western countries.

Stronger immune system

Several probiotic strains can strengthen immune functions and reduce the risk of infections, such as influenza and the common cold. Currently, there is research that investigates the effect of probiotics on COVID-19 patients.

Skin health

There is also evidence supporting the hypothesis that probiotics can reduce acne, rosacea, and eczema symptoms. Acne is a skin’s sebaceous glands inflammation, and due to the anti-inflammatory effects of probiotics, it could alleviate the symptoms and even treat the problem itself.

Anti-aging effects

Some studies suggest that probiotics can extend lifespan by consuming the correct type of probiotics, the ability of cells to replicate increases.

The relevance of probiotics to COVID-19

There is currently active research to examine the effects of gut bacteria improvement on treating the infection of SARS-CoV-2. The disease can harm the immune system through something called a cytokine storm. Cytokines are responsible for causing excessive inflammation in the body, which is the root cause of many chronic diseases that increase the mortality risk.

As mentioned earlier, a healthy intestinal flora strengthens the immune system and reduces inflammation. Therefore, researchers believe that probiotic supplements may help recover from SARS-CoV-2 by limiting the excess production of cytokines. Moreover, patients with COVID-19 can develop gastrointestinal symptoms, diarrhea, nausea, vomiting, abdominal pain, and loss of appetite. These can be well-managed with probiotic supplementation.

Side effects of taking probiotics

side effects of probiotics

Probiotics can have specific side effects. They can trigger an allergic reaction when consumed in high dosages. In the first few days, it may cause an upset stomach, diarrhea, or bloating. Changes in the gut microflora can cause more gas than usual. These symptoms usually go away incrementally as the body gets used to the changes of the intestinal flora. People who have problems with their immune systems must be extra cautious and consult with a doctor before taking probiotics.

Many people wonder whether it is safe to take probiotics daily. In theory, yes. However, one must not exceed the recommended daily dosage. It is also important to stress that probiotics must be treated as natural supplements and not as a medicine or something that substitutes a healthy diet and exercise.

Takeaway about probiotics

Probiotics are living microorganisms that can contribute to improving the intestinal flora of the body. This effect can lead to many health benefits when consumed in adequate amounts. There are many different strains of healthy bacteria, and each can help with various diseases.

Beneficial effects may include weight loss, improving the proper function of the digestive system, reducing inflammation, and strengthening the immune system. The latter two may be effective against the novel coronavirus, Sars Cov-2, and it can also help regenerate the body after the illness. Though more research is necessary, some evidence suggests that certain probiotic strains can aid weight loss. There are also promising results that psychobiotics, which are specific strains of bacteria, could improve cognitive and neurological disorders, such as Alzheimer’s disease and Parkinson’s disease. Moreover, probiotics may improve symptoms of depression and anxiety. Human health scientists’ main goal is to standardize the controversial results of thousands of studies and then translate them into apparent recommendations for therapeutic probiotic use.

Maintaining a healthy gut consists of more than taking probiotics. Following a healthy diet and consuming fibers that function as prebiotics are just as important. Like many other supplements, probiotics can also cause side effects; therefore, caution is always advisable. Before radically changing your gut bacteria, always consult with a gastroenterologist or get advice from a trusted healthcare practitioner.

Gianluca Tognon

Gianluca Tognon

Gianluca Tognon is an Italian nutrition coach, speaker, entrepreneur and former associate professor at the University of Gothenburg. He started his career as a biologist and spent 15 years working both in Italy and then in Sweden. He has been involved in several EU research projects and has extensively worked and published on the association between diet, longevity and cardiovascular risk across the lifespan, also studying potential interactions between diet and genes. His work about the Mediterranean diet in Sweden has been cited by many newspapers worldwide including the Washington Post and The Telegraph among others. As a speaker, he has been invited by Harvard University and the Italian multi-national food company Barilla.

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