What Are Probiotics? Your Guide to Healthy Gut Bacteria

Written by Dr. Michael Ruscio, DC on October 9, 2020

Written by Dr. Michael Ruscio, DC on October 9, 2020 — Reviewed by Hilary Watts

Probiotics Defined

Probiotics Defined|
What Are Probiotics Good for?|
Why We Need Probiotics More|
How Do Probiotics Help You?|
Prebiotics and Synbiotics|
Probiotic Foods|
Probiotics For Gut Health|
Probiotics for Non-Digestive Conditions|
Simplifying Probiotics|
Quality Assurance|
Probiotic Safety|
Reasons to Take Probiotics|

Key Takeaways:

Probiotics are often referred to as “good bacteria” for your gut.
This good bacteria can help to restore and maintain balance in your gut microbiota, a complex ecosystem in your digestive system.
Supporting a healthy gut microbiome with probiotics can help prevent or heal from issues like SIBO, IBS, and leaky gut.
The gut microbiota also has further reaching implications like impacting brain health, mood, thyroid health, and immunity.
Though diet can be a great source of probiotics, it can be difficult to obtain the dosages that have been shown to be effective in research, which is why dietary supplements may be the optimal choice.

Probiotics, often dubbed “friendly bacteria,” are live microorganisms that, when consumed in adequate amounts, provide a wide range of health benefits. This is because they help balance the gut microbiota—a remarkable ecosystem in the digestive system that contains trillions of microorganisms like bacteria, fungi, viruses, and other microbes.

By balancing the microbiota with probiotics, the ripple effect it has on your health is huge (even bigger than previously thought with new research I see coming in every year).

So let’s explore what probiotics are, the good they do for your health, and how to select probiotic-rich foods and supplements that can help optimize gut health and beyond.

Probiotic Snapshot

Probiotics are live microorganisms that live in your digestive tract and confer health benefits when consumed. And while they can be obtained through foods (sauerkraut, kombucha, miso, kimchi, etc.), the most concentrated way to get them is via probiotic supplements.

What Are Probiotics Good For?

Probiotics are important for maintaining the health of your microbiome, the complex ecosystem we talked about, that includes around 300 to 500 bacterial species. [1] These microorganisms perform critical functions for your digestion, hormones, nervous system, and immune system. [1]

The balance of healthy and harmful bacteria in your gut has far-reaching consequences for your health. Gut dysbiosis is an imbalance of microorganisms in your digestive system, much like a garden overrun with weeds. Dysbiosis doesn’t just lead to digestive symptoms, but it can negatively impact mood, energy, skin, joint health, metabolism, sleep, immune function, hormone balance, thyroid function, and more.

The good bacteria in probiotics can help to restore and maintain balance in your gut microbiota — the world of bacteria in your gut — and thus, it can help with many different symptoms and conditions.

Why We Need Probiotics More Than Ever

People in traditional societies had far more exposure to live bacteria than most of us do today. Natural childbirth, breastfeeding, contact with animals, contact with soil, and consumption of whole and fermented foods all helped to maintain a diverse human microbiome.

Our environment is much more sterile today. We routinely diminish our exposure to bacteria through Cesarean birth, antibiotics, and the use of antibacterial soaps and cleaners. Unhealthy diets that are low in fiber and high in sugar compound the problem. Even a sedentary lifestyle and poor sleep habits can negatively impact your beneficial bacteria. [2, 3]

In today’s world, bacterial imbalances in the digestive tract are the norm.

How Do Probiotics Help You?

Probiotics help to improve the balance of organisms in your gut, [4, 5, 6] reduce overzealous immune system activity, [7, 8] and reduce inflammation in the gut and elsewhere in the body. [4, 9] Probiotics are also antibacterial, antifungal, and antiparasitic and help to eliminate bad bugs.

When you understand the connections between your gut health, your immune system, inflammation, and nutrient absorption, it’s easier to appreciate the far-reaching impact of your gut health.

Immune System
Your small intestine contains the largest density of immune cells in your body. This is one reason why the health of your digestive tract and the health of your immune system are so closely linked. If your gut bacteria are unbalanced, your immune system may be chronically activated into an overzealous response. [10, 11]

Inflammation
An overzealous immune system produces inflammation in the gut and elsewhere in the body. Chronic inflammation is a major factor in many health conditions, including rheumatoid arthritis, [12] and cardiovascular disease. [13, 14]

Nutrient Absorption
Inflammation also damages the lining of the digestive system. [15] This can impair nutrient absorption. If you eat a healthy diet but don’t absorb nutrients well, this can be similar to eating an unhealthy diet.

What Are Prebiotics and Synbiotics?

Prebiotics are the fiber-rich foods that feed gut bacteria. If your gut is in good health, a diet rich in prebiotic foods can be very beneficial. However, it’s important to note that prebiotics may cause problems for some. That’s because prebiotics also feed bad gut bacteria.

Some patients with gut issues may actually need to restrict their intake of prebiotics. The low FODMAP diet is designed to restrict prebiotic foods and can be very helpful for patients with IBS and IBD. [16, 17, 18, 19, 20, 21, 22]

Synbiotics are dietary supplements that combine probiotics and prebiotics. While this is great for some, a synbiotic supplement may not be the best probiotic choice for people with digestive issues.

Probiotic Foods

Diet can be a great source of probiotics. However, through diet alone, it can be difficult to obtain the dosages that have been shown to be effective in research. For therapeutic doses of probiotics, dietary supplements may be a better choice.

Here are some of the probiotic species and dosages found in probiotic foods.

Food	Species	Amount	Equivalent Dose
Sauerkraut	Leuconostoc mesenteroides Lactobacillus brevis Pediococcus pentosaceus Lactobacillus plantarum	3 billion CFUper cup	1/8 capsuleLacto-Bifido Blend Probiotic
Yogurt [23, 24]	Lactobacillus acidophilus Streptococcus thermophilus Lactobacillus delbrueckii subsp. bulgaricus	2.5 billion CFUper cup	1/10 capsuleLacto-Bifido Blend Probiotic
Lacto-fermented Pickles [25, 26]	Lactobacillus casei Lactobacillus rhamnosus Lactobacillus plantarum Lactobacillus brevis	1.3 billion CFUper pickle	1/20 capsuleLacto-Bifido Blend Probiotic
Kefir [27]	Lactobacillus brevis Lactobacillus acidophilus Lactobacillus caseiLactococcus lactis Saccharomyces cerevisiae	2.5 billion CFUper cup	1/10 capsuleLacto-Bifido Blend Probiotic
Kimchi [28]	Weissella koreensis Lactobacillus sakeiLactobacillus graminis Weissella cibaria Leuconostoc mesenteroides	11.5 billion CFUper ½ cup	1/2 capsuleLacto-Bifido Blend Probiotic

Benefits of Probiotics for Gut Health

Probiotics are best known for their ability to help with various gut health conditions. A large volume of research supports this.

Probiotics Support These Conditions
High level of scientific support for:
Irritable Bowel Syndrome (IBS) Gas, bloating, diarrhea, constipation, abdominal pain	Inflammatory Bowel Diseases (IBD) Crohn’s disease and ulcerative colitis	Mood Depression and Anxiety
Gut Imbalances SIBO, H. pylori, candida/fungus, pathogens, antibiotic associated diarrhea	Leaky Gut Gut damage and permeability	Infections Vaginal infections, urinary tract infections, tooth decay
Limited, but encouraging, scientific support for:
Cognition Cognitive function, brain fog	Hormonal Health Thyroid health, PCOS, endometriosis, bone density	Allergies Dairy intolerance, seasonal allergies
Autoimmune Conditions Type 1 diabetes, multiple sclerosis, rheumatoid arthritis	Metabolic Health Blood sugar, cholesterol, blood pressure, weight loss	Sleep Sleep quality and Disruption

Here are some of the research highlights:

Use of Probiotics can be helpful for symptoms of irritable bowel syndrome (IBS), which include bloating, constipation, loose stools, diarrhea, abdominal pain, gas and fatigue. [29, 30, 31, 32, 33]
Probiotics have been CLEARLY shown to be effective in treating small intestinal bacterial overgrowth (SIBO), both in improving symptoms and improving lab values. [34, 35, 36]
Probiotics help to repair the intestinal lining in leaky gut syndrome. [37, 38, 39, 40]
Probiotics can be very helpful in treating bacterial, fungal and parasitic gut infections. [41, 42, 43, 44]
Probiotics have been found to be effective for inflammatory bowel disease (IBD), including Crohn’s disease [45] and ulcerative colitis. [45, 46, 47]
79% of studies reported reduction in reflux and related symptoms (heartburn, indigestion, regurgitation, nausea and gas) after probiotic treatment. [48]
Two recent research reviews concluded that probiotics are helpful for constipation, significantly increasing stool frequency and increasing gut transit time. [49]
Probiotics work to reduce antibiotic-associated diarrhea. [50, 51, 52]

Benefits of Probiotics for Non-Digestive Conditions

Probiotics aren’t just good for digestive health. Research has found that probiotics are effective for a number of non-digestive conditions. Probiotics:

Decrease the incidence of respiratory tract infections in children, [53] urinary tract infections [54] and vaginal infections in women. [55, 56]
Decrease oral pathogens that cause cavities, gingivitis and periodontal disease and may be beneficial for maintenance of oral health https://www.ncbi.nlm.nih.gov/pubmed/16827601. [57]
Have been associated with significant improvements in depression. [58, 59, 60] Research also shows some anti-anxiety effect from probiotics, but the data isn’t conclusive. [61, 62, 63, 64, 65, 66]
Can dampen symptoms of stress in healthy adults. [67, 68, 69, 70]
Help with sleep quality [71, 72, 73, 74, 75]
Can help with lactose intolerance [76] and gluten intolerance. [77, 78]
Can improve seasonal allergies [79, 80] and may prevent or reduce the formation of allergies in children. [81]
Have improved cognition in patients with Alzheimer’s, [82, 83] bipolar disorder, [84] and Fibromyalgia. [85] Probiotics may help IBS patients reduce symptoms of brain fog. [86]
Can reduce the need for thyroid medication and reduce fatigue in hypothyroid patients. [87]
May reduce the risk of autoimmunity for children at risk of type 1 diabetes when taken in infancy. [88]
Helped MS patients to reduce disability, lower insulin resistance, and reduce inflammatory markers. [89]
May help to improve rheumatoid arthritis symptoms. However not all studies show improvements. [90, 91, 92]
Can help with skin conditions. Topical probiotic treatments were effective for treating acne. [93, 94] Probiotic supplements also led to improvements in dermatitis. [95, 96]
May have benefits for babies, including, less colic and irritability, less diarrhea, fewer spitting episodes, and fewer respiratory infections. [97]
May help women during pregnancy to have fewer incidences of gestational diabetes, pre-eclampsia, excessive weight gain, and vaginal bacteria infections. [98]
May also lower infant death rates in babies born to moms who take probiotics during pregnancy. [99]

Simplifying Probiotics

There are a dizzying number of probiotic strains available in supplement products. However, here’s a trick to keep things simple: most every probiotic can be organized into one of these three categories:

CATEGORY 1	CATEGORY 2	CATEGORY 3
Lactobacillus & bifidobacterium species predominated blends	Saccharomyces Boulardii (a healthy fungus)	Soil-Based Probiotics using various bacillus species
These are the most well-researched, with over 500 trials assessing their validity. These live microorganisms are also known as lactic-acid producing probiotic bacteria. They typically do not colonize the host but do improve the health of the host.	The second most researched probiotic, with over 100 studies. Saccharomyces boulardii (S. Boulardi for short) is not a normal part of human microbiota, meaning it does not colonize us but does improve the health of the host.	The third most researched category of probiotics is soil-based probiotics. This group has roughly 14 clinical trials evaluating their effectiveness. This category is also known as spore-forming bacteria. This category of probiotic can colonize the host. [100]

You don’t need to try every probiotic product on the market. Instead, use one quality formula from each category, and take them all together. Wait a few weeks and reevaluate your symptoms. If you are seeing some level of improvement, keep going. If not, you can discontinue probiotic therapy and don’t need to try a different formula.

In my clinical experience, taking all three categories together has been the difference between people experiencing minimal results or impressive results.

Research supports this approach to taking probiotics. When mixtures of several probiotics were compared with single strains of probiotics in the treatment of IBS, the systematic reviews and meta-analyses indicated that the multi-strain probiotics were more effective than single-strain probiotics. [101, 102]

Quality Assurance

Probiotic products are not highly regulated in the United States. Several studies have shown that a surprising number of probiotic supplements do not contain the species and concentrations listed on their label, or contain unacceptable microorganisms. [103, 104]

When shopping for probiotic supplements, look for these indicators of quality:

A clearly stated list of species
A clearly stated number of colony-forming units (CFUs) in the billions
A manufacture date or expiration date
Labeled free of common allergens and other substances you may wish to avoid (e.g. gluten-free, non-GMO, vegan)
Good Manufacturing Practices (GMP) certification
Lab-verified for probiotic species and potency by third-party analysis (independent lab testing)

My line of probiotic supplements meets all of these quality assurance criteria.

Probiotic Safety

Probiotics are safe and have few side effects. The National Institute of Health states that probiotics are generally safe, even for premature infants. [105]

“Given the large quantities of probiotics consumed around the world, the numbers of opportunistic infections that result from currently marketed probiotics are negligible. For example, probiotics have been administered to thousands of newborn infants, including some who were premature, without a single case of sepsis.” [105]

There Are a Lot of Reasons to Take Probiotics

Some medical professionals still claim that there is no evidence that probiotics are effective. Clearly these “experts” haven’t spent hundreds of hours combing through the research.

Of course, more research is always needed to refine our understanding. And new studies into probiotics are published regularly.

With more than 500 clinical trials to support their use in maintaining gut health and treating a wide variety of symptoms and conditions, probiotics simply make sense.

Dr. Michael Ruscio is a DC, natural health provider, researcher, and clinician. He serves as an Adjunct Professor at the University of Bridgeport and has published numerous papers in scientific journals as well as the book Healthy Gut, Healthy You. He also founded the Ruscio Institute of Functional Health, where he helps patients with a wide range of GI conditions and serves as the Head of Research.

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