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Can Probiotics Prevent and Treat Diseases?

Can Probiotics Prevent and Treat Diseases?

Using evidence-based diet and natural therapies to enrich the body and address illness is a staple of integrative medicine practices. Consuming probiotics to increase health is a low-risk strategy with the potential for many benefits. However, a lot of confusion about this class of nutritional supplements exists because there are numerous probiotic strains, each with different abilities and strange-sounding names. Yet, probiotics are present in high concentrations in some foods, such as sauerkraut, kefir, kombucha, kimchi, and yogurt. With so many formulations of probiotics and probiotic-rich foods on the shelves in grocery stores, how does one pick a probiotic? Do they really work? If so, which ones are the best to use?

Background: What are Probiotics?

"Probiotics are live microorganisms that are intended to have health benefits when consumed or applied to the body” (1). The live microorganisms in question are usually beneficial bacteria but can also be beneficial yeast.

The stomach is designed to burn away harmful microorganisms with acid as a protective mechanism. For sufficient numbers of bacteria to survive the acid bath in the stomach, a large number of bacteria must be consumed at one time. During food poisoning, high enough amounts of harmful bacteria overwhelm the stomach's protection and get into the small and large intestines. However, that exact mechanism can be exploited to flood the system with beneficial bacteria that increase health! Interestingly, there is evidence that consistent consumption of probiotics can even prevent food poisoning (2).

What Foods Provide Probiotics?

Bacteria are everywhere in the environment and live naturally on the surface of fruits and vegetables. When fruits and vegetables undergo the process of fermentation, specific bacterial strains multiply. In fermentation, enzyme action breaks down and chemically changes organic substances. The byproducts of fermentation create a favorable environment for certain kinds of beneficial bacteria, which grow in number quickly. If consuming these strains of bacteria has noticeable health benefits in the human body, they are deemed probiotic. 

Often, vegetables are fermented in a bath of salt and water. Cabbage soaked in salt water at room temperature makes sauerkraut, a sour-tasting but crunchy treat that tastes somewhat like a shredded pickle. Fermentation by salt is a type of lacto-fermentation because the process creates fast growth in Lactobacillus bacteria, which produces lactic acid from consuming sugars in the plant matter. The lactic acid content causes a sour taste, the hallmark of probiotic foods. Lactobacillus can stand an environment of salt, while other types of bacteria cannot. The harmful bacteria die off, so all that is left are the strains of bacteria that typically increase health. 

In the case of yogurt, milk is warmed, and Lactobacillus bacteria is added to it. Lacto-fermentation occurs because the added Lactobacillus multiplies rapidly, consumes the lactose (milk fat) from the milk, and creates the byproduct, lactic acid.

Many foods can be fermented to produce probiotics:

  • Sauerkraut and pickles (salt-fermented cabbage and cucumbers)

  • Yogurt and kefir (fermented milk)

  • Miso and tempeh (fermented soy)

How are Probiotics Measured in Supplements?

Probiotics can be produced in large amounts for easy consumption in capsules, chewables, or liquids. In the realm of probiotic supplements, the number of bacteria or yeast in supplements is measured in colony-forming units (CFU), which attempt to reflect the number of individual live microorganisms. The higher the CFU, the more microorganisms are in the supplement. However, a higher CFU count is not always better. At some point, a greater concentration doesn't provide more improvement (3). Also, realize that even though a supplement claims to have a certain amount of CFU, environmental conditions such as excess heat can destroy the live organisms.

Why Do Probiotics Have Strange Names?

Probiotics are identified by their scientific names, which are mostly Latin. The Latin names often reflect their shape or how they are derived. For example, Lactobacillus is composed of the Latin "lacto" and "bacillus." "Lacto" means "milk," and "bacillus" is the name for rod-shaped bacteria. 

The names are composed of the genus, species, subspecies (if applicable) (3), and the strain, which sometimes tags on letters and numbers as additional identifiers. This naming system organizes and labels life into groups that share characteristics; all species and subspecies in a genus share certain qualities and are related. However, different strains of probiotics within the same species can have different actions on the body and unique attributes that may make them more desirable. Probiotics are often labeled down the strain level when they promise specific health benefits.

Most probiotic supplements on the market consist of seven groups of microorganisms: Lactobacillus, Bifidobacterium, Saccharomyces, Streptococcus, Enterococcus, Escherichia, and Bacillus (3). Saccharomyces is a beneficial yeast rather than a bacteria. 

Sometimes, the genus in the name is abbreviated, so "Lactobacillus reuteri" becomes "L. reuteri." Note that each genus can have many different strains - some natural in the environment and some grown in the lab. Probiotics grown to have specific qualities or those commonly used in research are given strain identification numbers, for example, "L. reuteri DSM 17938."

How do Probiotics Work?

Probiotics share some characteristics as a group. Probiotics can (2, 4, 5):

  • Balance or "normalize" gut flora

  • Crowd out harmful bacteria by outnumbering them in the gut

  • Produce short-chain fatty acids (SCFA), which serve as energy for the gut barrier

  • Reduce inflammation in the intestine through the action of SCFAs, and provide resilience against metabolic diseases (ex. obesity, cardiovascular illness)

  • Increase movement of stool through the bowels

Certain probiotics can create vitamins in the intestinal environment (riboflavin, folate, and vitamin K) (6), strengthen the gut barrier by improving the tight junctions that seal the gut off from the rest of the body (2, 6), or increase enzyme activity to help break down food molecules (2). Additionally, a few probiotics have been observed to affect the brain, the immune system, and the endocrine system (2).

What Conditions Can Be Improved by Probiotics?

The long list of beneficial effects of probiotics is ever-increasing due to active scientific research. Currently known health benefits of various probiotics are the prevention or reduction of (3, 6-8):

  • Allergies

  • High cholesterol

  • Milk (lactose) intolerance

  • Diarrhea and constipation

  • Radiation-induced diarrhea

  • Inflammatory bowel disease (IBD)

  • Irritable bowel syndrome (IBS)

  • Ulcerative colitis (UC)

  • Cancer

  • Some inflammatory skin conditions such as atopic dermatitis

  • Vaginal yeast infections

  • Urinary tract infections

How Probiotics Address Key Conditions:

Probiotics Address Leaky Gut - "Leaky Gut" is the common name for a situation where the gatekeepers of the gut lining, the tight junctions, get compromised and allow overly large food particles across the gut membrane into the blood circulation. (When they are healthy, tight junctions only let select, small molecules through their gates.) Once these large food molecules get past a damaged tight junction and into the blood, the immune system treats them like foreign invaders and begins to attack them. This action can cause widespread inflammation, which can exacerbate or even cause chronic illness. The probiotic yeast Saccharomyces and many strains of probiotic bacteria help strengthen the gut barrier and restore function to the tight junction gatekeepers (2).

Probiotics Address Some Skin Conditions - Improving the gut barrier through taking probiotics can help improve some skin conditions (6). Dysbiosis is when harmful gut bacteria gain the upper hand in the gut microbiome (the landscape of all the microorganisms in the gut). Improving the balance of gut bacteria types can also impact the skin. Researchers now refer to the relationship between the health of the microbiome and the surface skin as the Gut-Skin Axis (9). A link has been established between a compromised gut barrier, imbalanced gut microorganisms, an altered immune response, and numerous skin conditions such as psoriasis, atopic dermatitis, acne vulgaris, skin cancer, and dandruff (9).

Probiotics can crowd out harmful bacteria and improve the gut barrier, making it a potent and valuable remedy for many skin conditions. 

As a bonus, probiotics applied directly to the skin have helped relieve symptoms. For example, people with various skin conditions have benefitted from applying probiotic-rich creams directly to their skin (10).

Probiotics Address Many Gastrointestinal (GI) Disorders - Using supplemental probiotics can ease the symptoms of many GI disorders - diarrhea, radiation-induced diarrhea, constipation, inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), and ulcerative colitis (UC). Many of these GI disorders may have started as leaky gut or imbalanced gut flora. Increasing the number of beneficial bacteria or yeast can help heal the intestinal barrier and restore the gut flora to a more balanced state.

Probiotics Can Reduce Recurrent Vaginal Yeast Infections - One of the go-to holistic treatments for persistent vaginal yeast infections is the inclusion of probiotic-rich yogurt in the diet. Anecdotally, consuming a low-sugar yogurt or a probiotic supplement with a high Lactobacillus acidophilus or Saccharomyces boulardii count can decrease the number and duration of yeast infections. However, research studies are mixed on the effectiveness of this strategy. It is undoubtedly a low-cost, non-invasive strategy worth trying, as it does work for many women (8).

Highlights of Some Beneficial Probiotics

L. acidophilus: This strain of Lactobacillus is excellent for diarrhea, constipation, radiation or antibiotic-induced diarrhea, lactose intolerance, general health, allergies, and some skin conditions.

Sources: nutritional supplements, Lacto-fermented foods (sauerkraut, pickles), fermented dairy (yogurt, kefir, some aged cheeses), fermented soy (miso, tempeh, natto), fermented tea (kombucha).

Bifidobacterium: Many strains of this bacteria work well on antibiotic-induced diarrhea.

Sources: Nutritional supplements, Lacto-fermented foods (sauerkraut, pickles), fermented dairy (yogurt, kefir, some aged cheeses), breast milk

B. longum: This is a good strain of Bifidobacterium for ulcerative colitis and Crohn's Disease.

Sources: Nutritional supplements, Lacto-fermented foods (sauerkraut, pickles), fermented dairy (yogurt, kefir), fermented soy (miso, tempeh), fermented tea (kombucha)

Saccharomyces boulardii: This strain of beneficial yeast is known to help suppress diarrhea-causing bacteria when taking antibiotics that reduce bacterial numbers in the gut (12). It also reduces the length of time of an episode of acute diarrhea (13).

Sources: Nutritional supplements, lychee, fermented dairy (kefir), fermented tea (kombucha)

How to Pick a Good Probiotic

Not all probiotics are created equally. Because they are microorganisms that confer benefits only when they are alive, efforts must be made to ensure they are still alive when you consume them. 

Interestingly, many organizations do not officially recommend specific amounts of probiotics, and there is no "daily recommended value" for them. However, many healthy cultures have included probiotics in their diets for millennia, so daily consumption of probiotics from food sources has a good record. Below are some general tips for picking out a good probiotic. 

1. On the label of a supplement or probiotic food, look for the words "live cultures" or "active cultures” (11).

2. Good general picks for food-based probiotics are yogurt, sauerkraut, kefir, kombucha, kimchi, or pickles. Make sure the sauerkraut and pickles are made with salt and not vinegar. (Salt stimulates fermentation, but vinegar halts it.)

3. CFU count matters. Just realize that higher numbers may not mean a better result, and it's probably better to start with small doses to see how your body reacts to them.

4. Ensure that the probiotics are correctly stored. Some probiotics can be in capsules and are okay at room temperature; however, some are very heat-sensitive and must remain refrigerated to provide live cultures.

5. Third-party testing or GMP certification indicates that the microorganisms were made under safe conditions and are less likely to be contaminated than in facilities that don't have such standards.

6. Consider having a doctor or nutritionist recommend a probiotic based on your family and personal medical history.

Who Should Not Take Probiotics?

"Probiotics have an extensive history of apparently safe use, particularly in healthy people” (1). There is evidence that humans were using the fermentation process safely as far back as 10,000 years ago (14). Many ancient cultures had fermented foods as part of their traditional diets. Yogurt was described as a medicine in the Indian Ayurvedic health traditions (15) close to three thousand years ago (16).

Probiotics are safe for most for most to consume. However, if probiotics worsen any symptoms, especially GI symptoms, discontinue them and see a doctor who can help diagnose GI disorders. Meanwhile, the following groups of people should not use probiotics unless otherwise directed by a doctor:

People with small intestine bacterial overgrowth (SIBO) (17): SIBO is a condition in which opportunistic bacteria get into the small intestine and flourish where they should not. Bacteria overgrowth in the wrong part of the gut causes many GI symptoms, including diarrhea or constipation, abdominal cramping, leaky gut, and malabsorption of nutrients. The addition of probiotics can worsen symptoms.

People with compromised immune systems (1): Because probiotics can have a substantial effect on the immune system, immunocompromised people should avoid probiotics. The combination of the compromised immune system, an influx of bacteria, and each person's unique chemistry increases the odds of an adverse reaction.

Premature babies (1): Tiny babies and premature babies do not have a fully developed immune system. Giving these little ones probiotics increases the risks of adverse reactions.

Anyone with a severe illness that requires hospitalization (1): The introduction of extra bacteria, even if the strains are beneficial, could burden the body, worsening the situation.

Consider a Nutrition Consultation or Executive Physical

Temecula Center for Integrative Medicine can determine if probiotics will be beneficial to improving your health and addressing your symptoms. Our practitioners can run tests (or complete an Executive Physical) if the situation warrants it, and develop customized nutrition strategies. Probiotic cultures have been used safely for centuries and have many health applications, including improving overall health and making one resilient to some chronic illnesses. Besides addressing many health issues, probiotic foods are often delicious - making them the perfect addition to any diet!


Jonathan Vellinga, M.D.

Jonathan Vellinga, MD is an Internal Medicine practitioner with a broad interest in medicine. He graduated Summa cum laude from Weber State University in Clinical Laboratory Sciences and completed his medical degree from the Medical College of Wisconsin.​

Upon graduation from medical school, he completed his Internal Medicine residency at the University of Michigan. Dr. Vellinga is board-certified with the American Board of Internal Medicine and a member of the Institute for Functional Medicine.




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