Beginner’s Guide to Probiotics

A beginner's guide to probiotics explained

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In this beginner’s guide to probiotics, we answer some of the most common questions and how they directly impact your health.

Your body’s microorganisms are said to outnumber your cells by a 10-to-1 ratio. According to a recent study, the ratio is closer to 1-to-1 (1, 2).

You have 39–300 trillion germs inside you, according to these estimations. Whichever estimate is most correct, the total is unquestionably significant.

The bulk of these bacteria live in your stomach and are completely harmless. Some are beneficial, while others can cause sickness (3).

Numerous health benefits have been attributed to having the correct gut bacteria, including the following (4, 5):

  • slimming down
  • better digestion
  • improved immune system
  • a more youthful appearance
  • certain diseases have a lower risk

When probiotics, a form of friendly bacteria, are consumed, they provide health advantages.

They’re commonly used as supplements to aid in the colonization of your stomach with beneficial microbes.

The health benefits of probiotics are discussed in this article.


Probiotics are living bacteria that provide health benefits when consumed (6).

The scientific community, on the other hand, frequently argues about the benefits and which bacteria strains are to blame (7).

Probiotics are often bacteria, however, some yeasts can also serve as probiotics. Viruses, fungi, archaea, and helminths are among the numerous microorganisms in the gut that are being researched (8).

Probiotics can be found in supplements as well as meals that have been fermented by microorganisms.

Yogurt, kefir, sauerkraut, tempeh, and kimchi are all probiotic foods. Prebiotics, on the other hand, are carbs — usually dietary fibers — that help feed the friendly bacteria already present in your gut (9).

Synbiotics are food products that contain both prebiotics and probiotics. Friendly bacteria, as well as food for the bacteria to ingest (prebiotics), are frequently combined in one supplement called a synbiotic (10).

Lactobacillus and Bifidobacteria are the most frequent probiotic bacteria. Saccharomyces, Streptococcus, Enterococcus, Escherichia coli, and Bacillus are some of the more frequent types.

Each genus has a number of species, and each species has a number of strains. Probiotics are identified on labels by their unique strain (which includes the genus), species, subspecies (if applicable), and a letter-number strain code (11).

Probiotics have been discovered to help with a variety of health issues. As a result, selecting the appropriate type — or types — of probiotics is critical.

Broad-spectrum probiotics, also known as multi-probiotics, are supplements that contain multiple types of probiotic bacteria.

Despite the positive data, more study on the health effects of probiotics is required. Some experts have raised concerns about the “dark side” of probiotics, urging caution and stringent control (12, 13).

Probiotics are living microorganisms that boost health when consumed in adequate amounts. There are many different types, and you can obtain them from foods or supplements.


The gut flora, gut microbiota, or gut microbiome is the complex population of bacteria in your gut (14, 15).

Bacteria, viruses, fungi, archaea, and helminths make up the gut microbiota, with bacteria accounting for the great majority. A complex eco-system of 300–500 bacterial species lives in your gut (16).

The colon, or large intestine, is the last portion of your digestive tract and contains the majority of your gut flora.

Surprisingly, your gut flora’s metabolic activities are similar to those of an organ. As a result, the gut flora is sometimes referred to as the “lost organ” by scientists (17).

Your gut flora plays a crucial role in your overall health. Vitamins, such as vitamin K and several B vitamins, are made there (18).

It also converts fibers into short-chain lipids like butyrate, propionate, and acetate, which nourish your gut wall and aid in a variety of metabolic processes (19, 20).

These fats also help to build your gut wall and increase your immune system. This can assist prevent harmful compounds from entering your body and activating your immune system (21, 22).

Your gut flora is extremely sensitive to what you eat, and studies have connected an unbalanced gut flora to a variety of ailments (23, 24).

Obesity, type 2 diabetes, metabolic syndrome, heart disease, colorectal cancer, Alzheimer’s, and depression are thought to be among these disorders (25, 26, 27, 28).

Probiotics and prebiotic fibers can help restore this equilibrium, allowing your “forgotten organ” to perform at its best (29).

Your gut flora consists of hundreds of types of microorganisms. These microorganisms perform numerous important bodily functions.

Illustration about <a href=Probiotics and the Digestive System – Beginners guide to probiotics” class=”wp-image-4634″/>
Illustration about Probiotics and the Digestive System


The effects of probiotics on intestinal health have been extensively studied (30).

Probiotic supplements have been shown to aid in the treatment of antibiotic-associated diarrhea (31).

When patients take antibiotics for an extended period of time, they frequently have diarrhea, even after the infection has been eliminated.

This is because antibiotics kill many of your gut’s natural bacteria, causing the gut balance to alter and allowing bad bacteria to thrive.

Probiotics may also aid in the treatment of irritable bowel syndrome (IBS), a common digestive illness, by alleviating symptoms such as gas, bloating, constipation, diarrhea, and other discomforts.

The evidence for probiotic supplementation’s usefulness in the treatment of IBS is equivocal. According to a recent study, seven of the trials found that probiotic administration improved IBS symptoms, whereas four did not (32).

According to research, multi-strain probiotic pills appear to help most people with IBS, especially when used for more than 8 weeks.

However, there is still a lot that we don’t know regarding probiotic treatment for IBS. The following questions have yet to be answered (33):

Early outcomes of IBS probiotic treatment are promising, according to researchers, but more major trials are needed before healthcare providers can confidently prescribe probiotic treatments for IBS (34).

Probiotic supplementation has also been shown to help with inflammatory bowel conditions like Crohn’s disease and ulcerative colitis in several studies. More investigation is needed, according to researchers, before the treatment can be proved to be beneficial (35).

Probiotics may also aid in the fight against Helicobacter pylori infections, which are one of the leading causes of stomach ulcers and cancer (36, 37, 38).

If you’re having trouble with your digestion and can’t seem to get rid of it, a probiotic supplement might be worth looking into. However, make sure to speak with your doctor first.

Probiotics may be effective against various digestive problems, including antibiotic-associated diarrhea and IBS.

Probiotics. gut flora Good and Bad bacteria - Beginners guide to probiotics
Probiotics. gut flora Good and Bad bacteria


Obese people have different gut microbes than slim people, according to some research (39).

Obesity is linked to gut microorganisms in both infants and adults, according to research. It also reveals that microbial alterations in the gut play a role in adult obesity development (40).

As a result, many experts believe that gut bacteria play a role in body weight regulation (41, 42).

While further research is needed, it appears that some probiotic strains can help with weight loss (43).

However, researchers caution against jumping to conclusions, pointing out that there are still many unknowns.

Among the unknowns are (44):

  • the probiotic strains that will be employed
  • the treatment’s dosage and duration
  • the treatment’s long-term impacts
  • the intersection of age, gender, health issues, and way of life

In one study, 210 participants with central obesity (extra belly fat) were given the probiotic Lactobacillus gasseri on a regular basis. Over the course of 12 weeks, participants dropped an average of 8.5 percent of their belly fat (45).

Within four weeks of stopping the probiotic, the subjects regained their belly fat.

More research is needed to see if Lactobacillus rhamnosus and Bifidobacterium lactis can help with weight loss and obesity prevention (46).

Though more research is necessary, some evidence suggests that certain probiotic strains can aid weight loss.


The stomach and brain are linked in a mechanism called the gut-brain axis, according to research published in the last decade. This axis connects the central and enteric neural systems of the organism, the latter of which is in charge of digestion (47).

According to some studies, some gut microorganisms can influence your brain via this axis in both health and disease. These microorganisms belong to a new field known as “psychobiotics” (48, 49, 50).

Psychobiotics have been shown in studies to aid in the treatment of cognitive and neurological illnesses such as autism, Alzheimer’s disease, and Parkinson’s disease (51).

Much current research is focused on determining which microorganisms are present and how they interact with the brain (52).

Some experts believe that supplementing with certain strains of probiotics, rather than using psychiatric medicines, may be a better way for some people to cope with the emotional stress, loneliness, and grief brought on by the present COVID-19 pandemic (53).

Early research holds promise that certain gut bacteria called psychobiotics may be able to help treat cognitive and neurological disorders, such as autism, Alzheimer’s disease, and Parkinson’s disease.


Probiotics provide a slew of other advantages. They may aid in the treatment of the following conditions:

Probiotics lower systemic inflammation, which is a major cause of many disorders (54).

Depression and anxiety: In persons with clinical depression, the probiotic strains Lactobacillus helveticus and Bifidobacterium longum have been proven to improve feelings of anxiety and depression (55).

Several probiotics have been proven to reduce total and LDL (bad) cholesterol levels, while the evidence is still inconclusive (56).

Blood pressure: Probiotics may help to lower blood pressure slightly (57).

Immunological function: Several probiotic strains have been shown to boost immune function, potentially lowering the risk of illnesses like the common cold (58, 59).

Skin health: There’s some evidence that probiotics can help with acne, rosacea, eczema, and other skin conditions (60).

Anti-aging. Though research is limited, there is evidence that probiotics may help people live longer by improving the ability of cells to multiply themselves (61).

This is only a small portion of the benefits of probiotics, as ongoing research indicates a wide range of potential health effects.

In addition to their potential effects on weight loss, digestion, and neurological disorders, probiotics may improve heart health, immune function, and symptoms of depression and anxiety.

Overview of Probiotics poster - Beginners guide to probiotics
Overview of Probiotics poster


Improved gut microbiome by probiotic supplements and diet, according to some studies, could be a strategy for fighting and treating an infection with the new coronavirus SARS-CoV-2. COVID-19, which stands for coronavirus disease 2019, is an illness caused by this infection (62).

COVID-19 is known to wreak havoc on the body’s immune system by causing a “cytokine storm” of pro-inflammatory cytokines. This is thought to be the primary cause of poor health and even death (63).

Probiotic supplements may assist hasten recovery from coronavirus by blocking or reducing this “cytokine storm,” according to researchers because intestinal flora has been found to improve the immune system and fight inflammation (64).

GI symptoms such as diarrhea, nausea, vomiting, stomach pain, and loss of appetite have also been described in persons who have COVID-19 (65).

Probiotics may help prevent the coronavirus by blocking the angiotensin-converting enzyme (ACE) receptor, which is where the SARS-CoV-2 infection enters the body to infect gastrointestinal cells, according to some studies (66).

Another link between COVID-19 and probiotics that have been hypothesized is the “gut-lung axis.” This is a communication and interaction mechanism that happens between the gut and lung tissues via microorganisms in the human microbiome (67).

Lung illnesses and respiratory tract infections have been linked to gut flora imbalances. Correcting those abnormalities, according to the researchers, may promote optimal lung health, which could help protect against infections like SARS-CoV-2 (68, 69).

Probiotic supplementation may boost immunological, pulmonary, and anti-inflammatory responses, which may help clear the SARS-CoV-2 infection, according to another study (70, 71).

All of these hypotheses are still in their infancy. More research is needed to corroborate the findings, according to the researchers.

One study recommends caution, claiming that not all probiotic strains have the same impact. It is debatable if probiotic supplementation can alter the gut microbiota content sufficiently to combat COVID-19 (72).

Some current research proposes that improving the gut microbiome through probiotic supplementation and diet may help treat the SARS-CoV-2 infection that causes COVID-19. Research is preliminary, and much more data and clinical trials are needed.


Most people tolerate probiotics well and consider them to be harmless. However, because probiotic rules vary, you must be cautious while selecting a product.

Choosing the Right Probiotics

You could feel overwhelmed when confronted with the vast array of probiotics now available. You’re not the only one who feels this way. It can be difficult to make a decision.

Probiotics are commonly sold in the United States as food additives, medications, or nutritional supplements. While the Food and Drug Administration (FDA) oversees each of them in its own way, the majority of foods and supplements do not require FDA approval before being sold (73).

As a result, some businesses take advantage of the probiotic craze to sell pills labeled as probiotics and make claims that aren’t supported by data (74).

Probiotic regulations vary considerably over the world, thus acquiring probiotics from different countries online is problematic. Food, cosmetics, and supplements that are not regulated are simple to come by in other countries, but their safety is unknown.

You may identify high-quality supplements by looking for companies that follow best practices, such as third-party testing.

The best option is to consult with your healthcare physician or ask for recommendations. They may be able to suggest products that they have tested and found to be safe and effective.

Side effects of probiotics

You may notice digestive side effects such as flatulence and minor abdominal discomfort in the first few days of using a probiotic pill (75).

However, once you’ve adjusted, you should notice an improvement in your digestion.

Probiotics can cause deadly infections in persons with weakened immune systems, such as those with HIV, AIDS, and a variety of other illnesses (76).

Consult your doctor before using a probiotic supplement if you have a medical issue.

Probiotic supplements may cause digestive symptoms, which should subside within a few days. They may also be dangerous for people with certain medical conditions.

Probiotics explained poster - Beginners guide to probiotics
Probiotics explained poster


In the last two decades, science has made significant progress in understanding the role of probiotics in human health and disease. Probiotic research is still in its early stages, and there is much to discover.

Despite extensive research, scientists are still trying to identify all of the many microbial species that exist in your gut. Understanding how they operate in human health requires identifying them.

In 2019, for example, researchers discovered approximately 2,000 previously unknown gut bacterial species. This was a significant step toward classifying the microorganisms that live in the human gut (77).

Following the identification of microorganisms, researchers must now link the numerous species, subspecies, and strains of germs to their effects on human health – and this is where things get complicated (78).

Thousands of research have been conducted to determine the health advantages of probiotics for a variety of clinical problems, but the results frequently contradict one another (79, 80).

One explanation for this is that data processing and analysis procedures for probiotics differ from country to country. As a result, study studies of published data are contradictory (81).

Probiotics research is difficult to standardize since the human body has a broad and diverse group of bacteria that differs between countries — and even between individuals within the same country.

Furthermore, bacterial strains, as well as the health and surroundings of their human hosts, are continually altering.

Researchers working on probiotics are tasked with categorizing trillions of constantly changing organisms in a variety of conditions.

This Herculean undertaking is only conceivable because of the development of computational analysis of the genomes of collective groups of bacteria (called metagenomics) in the last two decades (82).

Scientists must first standardize a mound of sometimes contradictory findings from thousands of trials, and then convert that evidence into clear therapeutic probiotic use guidelines (83).

Researchers are challenged with identifying all the microbiota in the vast and changing microbiome of the human gut. They also need to establish a system for standardizing research results to develop clear therapeutic recommendations for probiotic uses.


Taking a probiotic supplement isn’t enough to keep your gut healthy.

Many lifestyle variables affect your gut bacteria, so daily nutrition and activity are just as important.

Probiotic supplements, on the other hand, may provide a wide range of advantages with few negative effects. As a result, if you’re looking to improve your gut health, they might be worth a go.

To ensure you’re trying the proper strains in the right dosages and avoiding any negative effects, consult your healthcare physician first.

Perhaps you’re wondering if probiotics could help you with a certain ailment. If that’s the case, you should look at the World Gastroenterology Organization’s Global Guidelines. It includes a list of probiotics, as well as conditions and dosage recommendations.

When using probiotics for the first time, proceed with caution. Use a reputed product, begin carefully, and seek advice from a qualified healthcare professional.

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