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Prebiotics, Probiotics, and Antibiotics, Oh My

Zoe Schilling

PharmD. Candidate, 2022

Ohio Northern University


What is a Probiotic?

Defined by the World Health Organization (WHO), a probiotics are live microorganisms which when administered in adequate amounts confer a health benefit on the host.” Basically, probiotics are live “good” bacteria, usually digested in the form of a pill, powder, or liquid. In order to be labeled a probiotic, scientific evidence for the health benefit must be documented.

Common forms of probiotics include:

● Bifidobacterium spp.

● Lactobacillus spp.

● Bacillus coagulans (bacterial spore)

● Saccharomyces boulardii (fungus)

Prebiotics verses Probiotics:

Whereas probiotics are the direct “good-for-you” bacteria that you ingest, usually in the form of a pill. Prebiotics are non-digestible foods or ingredients that promotes the growth of these beneficial microorganisms in your gut. In other terms, prebiotics are food for your gut bacteria (for your probiotics). Some examples include oats, bananas, onions, garlic, asparagus, and more. Hence, a diet high in fiber is wonderful for your gut microbiome.

What are Synbiotics?

These are a combination of prebiotics and probiotics that are commonly found in foods such as pickles, sauerkraut, kimchi, and kefir. These provide both “food” for the bacteria in your gut as well as provide significant amounts of live bacteria themselves. Cabbage for example, is high in indigestible plant fiber which nourishes gut microbes and when fermented to sauerkraut, it also provides Lactobacillus species.

What is an antibiotic’s effect on the gut microbiome?

Antibiotic use can have several negative effects on the gut microbiota. Some of these effects includes reduced species diversity, altered metabolic activity, and the selection of antibiotic-resistant organisms. These harmful effects could lead to antibiotic-associated diarrhea or recurrent Clostridioides difficile (C. diff) infections.

How do Probiotics Improve Health?

· Suppression of pathogens

· Stimulation of the immune system

· Reduction of inflammation

· Destruction of toxins

· Production of essential vitamins

· Improvement of the integrity of the gut lining

What is the best time to take a probiotic?

This really depends on what symptoms you’re experiencing and what your end goal is. For people who are trying to replenish the good bacteria in their gut following a course of antibiotics, most doctors recommend spacing the probiotic at least 4 hours from the time that you take your antibiotic. This is because antibiotics seem to suppress all bacteria, including the good ones in your gut. Hence, it might be a waste of money to take at the same time as your antibiotic if the antibiotic will prohibit the absorption and beneficial effects of the probiotic.

Some experts recommend taking the probiotic either first thing in the morning before eating breakfast or before going to sleep at night. Probiotics seem to be most effective when taken on an empty stomach to make sure the “good bacteria” makes it to the gut as quickly as possible.

Lisa Richards, a certified nutritionist and creator of the Candida diet, says the best time to take a probiotic is just before a meal or as you begin your meal. "This is the time when your stomach environment is at its least acidic because your body has not yet begun to produce stomach acid in large quantities to digest your food. Taking your probiotics at this time will make their passage to your gut a little easier and ensure you get the most from those beneficial bacteria."


Chutkan, Robynne. The Microbiome Solution. Read How You Want, 2017.

Mack DR. Probiotics-mixed messages. Can Fam Physician. 2005;51(11):1455-1464.

Lapidos, Rachel. Best Time to Take Probiotics for Your Gut Health. Vitamins and Minerals. 2022 April 11.

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