We hear about the importance of probiotics everywhere, from the cover of health magazines to your doctor’s waiting room, and on TV commercials, but how much do you actually know about these tiny bacteria?

The benefits of probiotics have been well documented by hundreds of in-depth clinical trials and studies, so it's no wonder that the world is buzzing about the remarkable impact they can have on your health. Not only are there over 100 known benefits associated with taking probiotics, but probiotics are also responsible for around 70% of your immune function (1). That's pretty impressive.

With an overwhelming amount of information and science to sift through, we decided to compile, into one handy guide, everything you need to know about probiotics.

Book mark this page to digest it in small doses, and get started on your path to a healthier gut. 

What Are Probiotics & How Do They Work?

In simple terms, probiotics are live bacteria that live along your digestive tract, supporting your body’s ability to absorb nutrition and fight off infection. While they are naturally occurring in your body, your probiotic levels can easily become unbalanced, leaving you with an insufficient amount. Unlike “bad” bacteria that do their best to make you sick, probiotics are “good” or “helpful” bacteria committed to keeping you healthy. 

The benefits of probiotics to us are countless:

♦ Crowd out “bad” bacteria, fungi, and yeasts

♦ Create enzymes specifically tasked with destroying harmful bacteria

♦ Create enzymes that counter the production of cholesterol in your bloodstream

♦ Stimulate the secretion of IgA, an immunoglobulin that stops foreign substances from entering your circulatory system

♦ Stimulate the secretion of regulatory T cells that are crucial for maintaining an optimally balanced immune system

♦ Produce vitamin B12, vitamin K2, and butyrate, which all play a significant role in maintaining your digestive health

♦ Promote strong bones

♦ Relieve acid reflux and indigestion

When you are consuming enough probiotics to ensure these tasks are being met, your immune system gets the boost it needs to help you stay as healthy as possible.

The Importance of a Good Gut

Hippocrates, who is considered by many to be the “Father of Modern Medicine,” said, “All disease begins in the gut.”

Around 80% of your immune system lives within your digestive system’s gastrointestinal tract (2). When your digestive system is not functioning properly, every part of your body can be affected, putting your health at risk. For example, your body may have trouble:

♦ Absorbing vitamins and minerals and allowing food proteins to enter your bloodstream

♦ Regulating hormone levels

♦ Eliminating toxins

♦ Initiating your immune response, putting you at a higher risk of all types of diseases, including autoimmune, cancers, and allergies

♦ Producing serotonin: Serotonin is a brain neurotransmitter that plays a critical role in maintaining a balanced mood. This means that probiotics can help combat depression and anxiety as well. Almost 90% of serotonin is made in the digestive tract (3).

When you are consuming enough probiotics to ensure these tasks are being met, your immune system gets the boost it needs to help you stay as healthy as possible.

Scientists have referred to the digestive system as your “second brain.” Simply put, when your digestive system isn’t healthy, your body’s entire well-being is at stake. This is why it is so important that you make every effort to keep your gut healthy.

a close-up of a baby's foot

Clinical Studies Support Benefits of Probiotics

A substantial amount of time, money, and effort has been devoted to probiotics research, making it virtually impossible to list all of the health benefits of probiotics. Below is just a snippet of the latest and greatest clinical research findings.

A 2015 study funded by the National Institute of Health (NIH) reconfirmed past research showing that probiotics play a significant role in promoting a healthy immune system (4). The study specifically found that probiotics can help with intestinal problems, some skin disorders, respiratory infections, and weight loss.

A 2017 study conducted by the University of Virginia School of Medicine found that probiotics, particularly lactobacillus, may reverse symptoms of depression, improving mental health (5).

Researchers from the University of Florida found that probiotics work to regulate your body’s immune response to allergies, reducing allergy-related nose symptoms (6).

Research published in 2017 stated that probiotics could be used as a therapy for the prevention and treatment of cancer because of their ability to modulate intestinal microbiota and tumor-suppressing properties (7).

Harvard Medical School published a report in January 2017 stating that research shows that probiotics have helped treat or prevent diarrhea, irritable bowel syndrome (IBS), Crohn’s disease, ulcerative colitis, urinary tract infections, vaginal infections, the recurrence of bladder cancer, eczema in children, and Clostridium difficile (C. diff) infections of the digestive tract (8).

University of California San Francisco researchers reported in a 2017 podcast that probiotics, specifically Lactobacillus acidophilus, can reach the mammary gland, which could prove to be pivotal for the prevention of breast cancer (9). They provide protective antioxidant and anti-cancer effects, decrease the abundance of IL-6 and C-reactive protein, and upregulate the immune system.

A report released by the National Center for Complementary and Integrative Health relayed that researchers have found probiotics to either help prevent or treat allergic disorders (eczema and hay fever), digestive disorders, colic in infants, periodontal disease and tooth decay, the common cold, and liver disease (10).

A recently completed study performed at Ontario’s McMaster University linked the use of probiotics to relieve symptoms of depression and gastrointestinal upset (11).

In 2015, researchers at Loughborough University determined that probiotics help prevent insulin resistance that results from consuming foods high in trans fats for an extended period of time [12]. Their study also found that probiotic supplementation can help normalize insulin functioning (12).

In an analysis published in 2015, researchers pooled together the results of 15 different studies on probiotics and cholesterol and compared their results (13). The researchers found that probiotics can significantly lower your total cholesterol, LDL (often referred to as “bad cholesterol”), waist circumference, body mass index, and inflammatory markers. The analysis highlighted five studies examining the short-term effects of yogurt with different probiotic strains on serum cholesterol levels. Within 2-8 weeks, participants experienced a 4% decrease in their total cholesterol levels and a 5% decrease in their LDL levels.

An article published in the Journal of Cardiovascular Disease Research detailed the positive effects probiotics can have on your cardiac health (14). Researchers reported that due to the cholesterol-lowering effects of probiotics, along with their ability to lower blood pressure, reduce inflammation, and help prevent insulin resistance, probiotics can help control or ward off cardiovascular diseases, including coronary heart disease (CHD), which is the leading cause of death for both men and women in the United States (15).

What Causes a Gut Imbalance?

There are numerous outside factors that upset the healthy balance of probiotics in your body. The most common reasons include:

Antibiotic Use

While there is no doubt that the discovery of antibiotics has prevented millions of deaths, there is a cost to taking them. Antibiotics are unable to distinguish between “good” and “bad” bacteria. Essentially, they will work to kill anything they come up against. When probiotics are killed, space opens up for bad bacteria and fungi that may be resistant to antibiotics can easily take over. They can thrive, leaving your levels unbalanced and your body struggling to regrow the good bacteria it has lost.


The frequent use of non-steroidal anti-inflammatory drugs (NSAIDS), such as Ibuprofen, Aleve, Motrin, Midol, and Advil, can kill your good intestinal bacteria.

Excess Stress

When your body is stressed, it can wreak havoc on your digestive system. By altering your gastrointestinal motility and secretion, stress can kill off and/ or greatly reduce the production of probiotics.

Consuming Some Natural Herbs

Several different herbs are frequently taken as natural antibiotics. Just like their synthetic counterparts, these herbs are unable to tell the difference between “good” and “bad” bacteria, causing them to kill any bacteria they come in contact with. These herbs include goldenseal, colloidal silver, and grapefruit seed extract (GSE).

Chlorine Consumption

We already know how effectively chlorine can kill bacteria in your pool, so it would stand to reason that the same would be true your body. Chlorine, which may be included in your tap water to kill any bacteria it harbors, will also kill the good bacteria living along your digestive tract.

Cancer Treatments

Both chemotherapy and radiation target any bacteria living in your body and can be particularly devastating to good bacteria.

Sugar and Sugar Substitute Consumption

Sugar is frequently added to foods as a preservative and preservatives have been shown to kill good gut bacteria. One study found that the common sugar substitute, Stevia, kills off large numbers of the probiotics living in your digestive tract (16).

a close-up of a white liquid being poured into a glass


When you are constipated, “bad” bacteria is allowed to hang out in your digestive tract much longer than it should be. Not only will it proliferate, but it will target your “good” bacteria.


Studies show that the genetically modified organisms (GMOs) that are often found in many of the foods we eat not only kill off good bacteria, but create conditions that are just right for bad bacteria to flourish (17).


The chemicals that may have been used to grow the food you eat, such as fertilizers, herbicides, and pesticides, as well as any additives and preservatives that may have been added to it, have been shown to kill off probiotics.

How To Increase Your Probiotics Intake

It is true that probiotics naturally occur in your body. However, this may not be enough to ensure you are taking advantage of all the health benefits they offer. Fortunately, there are ways to increase your intake. The two most common ways involve incorporating more probiotic-rich foods into your daily diet and taking a daily probiotic supplement.

Foods That Are Naturally High in Probiotics

There are certain foods that contain significant amounts of probiotics. Your top options include:

Live-Cultured Yogurt

Probiotics in yogurt have been shown to help keep the digestive tract free of harmful bacteria and increase cytokine-producing cells in the intestines, giving your immune system a huge boost (18). Be aware that this does not apply to all yogurts. Be sure to read labels and stay away from yogurts containing artificial sweeteners and flavors, sugar, and high fructose corn syrup. Only choose yogurt that states it has “live and active cultures” to ensure the probiotics will still be alive when you consume it, or make your own yogurt.


Sauerkraut is a surprisingly nutritious food that has plenty of vitamins and minerals, yet has no fat and few calories. As a fermented food, sauerkraut has the ideal conditions for the growth of beneficial probiotics. Probiotics in sauerkraut have been shown to improve your digestion and general health while acting as the first line of defense against harmful bacteria. A single serving of sauerkraut is believed to contain as many as 28 different probiotic strains, offering a wide array of health benefits (19).


Kefir, a fermented milk product, is considered one of the planet’s most probiotic-rich foods (20). In addition to other things, the probiotics in kefir have been shown to defend against E. coli and salmonella, fight against candida and harmful microbes, help restore digestive system balance, and reduce inflammation in the body.

Miso Soup

This traditional Japanese soup has been referred to “cancer-fighting probiotics in a bowl.” Miso, an organically grown fermented soy product, contains probiotics that enhance digestion, lower blood pressure, inhibit the development of cancerous tumors, prevent injury from cancer radiation treatments, and give your immune system a boost (21). You can also eat miso in a paste form.

| Probiotic Recipe: Raspberry Banana Smoothie |

a group of desserts in a bowlKombucha Tea

This fermented tea has long been known to be a rich source of probiotics. Its probiotics have been proven to help lower cholesterol levels, reduce the risk of heart disease, improve digestion, mood stability, and mental clarity, and reduce or eliminate the symptoms of everything from depression and anxiety, to fibromyalgia.

Ginger Beer

This naturally fermented beer is considered non-alcoholic because it contains less than 0.5% alcohol. The probiotics it produces during the fermentation process are particularly beneficial (23). For example, they relieve multiple stomach ailments, are used to treat inflammation, and reduce menstrual pain. Studies have also determined that ginger beer has the ability to destroy ovarian cancer cells and may be used to reduce the risk of developing colon cancer.


Often eaten as a Korean vegetable side dish, kimchi is fermented with the probiotic lactic acid bacteria. Studies have shown these probiotics to promote a healthy brain, colon, and immune system, reduce cholesterol, and help fight cancer and obesity (24).

How to Choose the Best Probiotic Supplement

If the thought of eating the foods listed above just doesn’t appeal, you can always opt to take a daily probiotic supplement. However, you will quickly learn that there are hundreds, if not thousands, of supplements on the market, making it almost impossible to determine which one is the right one for you. To make it much easier to choose the best probiotic supplement for you, we've outlined here what you need to be on the lookout for.

Before we get started, it is important to note that probiotics are generally safe for most people, but they could cause complications in patients who have a compromised immune system. You should always speak with your doctor before adding any type of supplement to your daily routine. Also, be aware that the University of Maryland Medical Center recently released information stating that patients with an artificial heart value may have an increased risk of developing bacterial infections when taking probiotics.

Different Strains For Different Pains

The first thing you need to know is that different probiotics have specific benefits. Not all probiotics provide the same health benefits, so if you are looking for help with a certain area of your health, you will need to find a supplement that contains probiotics intended for this condition, or opt for a broad-spectrum formula that contains numerous strains to target multiple issues. It's imperative that each supplement should list the specific strain of all the probiotics it contains on the label. Below you will find information on the most important probiotic strands and what specific benefits they offer.

Sometimes It's Ok To Judge a Book By Its Cover

Consider the packaging. A supplement that contains nothing but dead bacteria is a waste of money and effort. Be sure you choose a supplement that has been packaged and delivered to remain alive and healthy while sitting at the store or in your home. Your best option is a supplement that has been packaged in a thick, opaque bottle with silica gel desiccant packets. Always be sure to follow the storage directions on the label.

Liquid Probiotics Versus Probiotic Capsules

Consider what form the supplement comes in. Certain forms have to be handled differently. For example, liquid probiotics almost always have to be refrigerated, making it a bad choice if you travel consistently. (If they are not kept cold, the probiotics can die, leaving you with a useless product.) Specially sealed probiotic capsules tend to be a good option because they rarely need to be protected from heat, moisture, or light.

Check The Expiration Date

Look at the expiration date. When it comes to the expiration date listed on a probiotic supplement, this is the manufacturer’s guarantee that the bacteria inside will remain active and potent until that date. If there is no expiration date listed, immediately move on to another probiotic. Look for a date that allows you time to finish the entire bottle so that you won’t have to waste.

Consult Your Doctor

Verify that the supplement will not interfere with any medicines you may be taking. In some instances, probiotics may interact with certain medications. If you take any medications, check with your doctor or a pharmacist to determine what you must stay away from.

a group of fish swimmingThe Most Important Probiotics Strains

Finally, let’s look at the most important strains of probiotics and what they do best.

Lactobacillus acidophilus: L. acidophilus boosts immunity and supports healthy digestion, particularly in people who have a difficult time digesting lactose.

Bacillus laterosporus: B. laterosporus has been shown to effectively fight off an array of harmful organisms and has been proven to kill candida in a short period of time.

Bifidobacterium breve: B. breve plays a crucial role in colon health and is considered one of the probiotics best able to activate dendritic cells, boosting your immune system.

Bifidobacterium bifidum: One of the best-known probiotics, B. bifidum keeps unwanted bacteria out, enhances your immune system, plays a crucial role in allergy response, and helps ease digestion.

Bifidobacterium lactis: B. lactis is one of the most versatile strains of probiotics. It helps your body digest lactose, as well as all types of sugars, fats, and macronutrients while reducing the symptoms of ulcerative colitis, reducing the occurrence of diarrhea associated with antibiotic therapy, and supporting healthy cholesterol levels.

Lactobacillus salivarius: A potent antibacterial, L. salivarius is considered crucial for good oral health. In addition to fighting off bacteria in your mouth and small intestines, it relieves the symptoms of asthma and allergies, fights cancer, and lowers cholesterol levels.

Lactobacillus plantarum: L. plantarum has been shown to enhance lysine production. Lysine is an amino acid that supports hormone production, enhances the immune system, and supports calcium absorption.

Lactococcus lactis: There are plenty of benefits associated with L. lactis (26). They include reducing inflammation and allergies, increasing tumoricidal activity to fight off cancer tumors, strengthening the immune system (particularly in the elderly), improving cholesterol levels, and increasing blood glucose control in diabetics.

Lactobacillus gasseri: L. gasseri supports healthy digestion, promotes weight loss, combats obesity, and may lower glucose levels and improve glucose tolerance, which is of great importance for diabetics (27).

Lactobacillus brevis: L. brevis is another versatile strain that increases the production of natural killer cells to boost your immunity, supports digestive health, enhances the effectiveness of antibiotics, has potent antimicrobial properties, and helps improve the condition of your gums and overall oral health. Recent studies indicate that it may help combat ulcers caused by H. pylori (28).

Bifidobacterium longum: B. longum lessens the symptoms of Celiac disease, IBS, and allergies, while also boosting cognitive function, alleviating anxiety and depression, lowering cholesterol levels, and relieving inflammation.

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The Bottom Line

You are doing your gut a favor by removing substances that can destroy probiotics, like chlorinated tap water, sugar, antibiotics, GMOs, and harmful stress. Make sure to eat your daily serving of probiotic-rich foods from the list above to receive added probiotics benefits. And if you haven't already added a probiotics supplement, with at least 10+ strains of probiotics and a minimum of 25 billion CFUs to your daily routine, it's definitely time to do so.