Your gut is a lively place. Bacteria of all kinds live in your intestines and, for the most part, help you to thrive.
“The gut microbiome is a very complex ecosystem,” says Dr. Geoffrey Preidis, an assistant professor of pediatrics at Baylor College of Medicine and pediatric gastroenterologist at Texas Children’s Hospital in Houston. “There are many, many microbes that inhabit various niches within the intestine. Many of them work together. Many of them depend on each other.”
But sometimes, bacteria can make you feel ill, and a doctor may prescribe antibiotics to eliminate the pathogen.
While you’re battling strep throat or your child is getting over an ear infection, the same antibiotic that may be helping to fight back the infection may also be disrupting the ecosystem of microorganisms, collectively called the microbiota, in the gut.
“The problem is that antibiotics can cause a lot of collateral damage,” Preidis says. “They don’t just target that one bacterium that they’re prescribed to eliminate. They will also target and kill off a large portion of the otherwise normal gut microbiota that we all have within us.”
One of the common complications to antibiotic use is antibiotic-associated diarrhea, which is caused by a disturbance of the good bacteria that live inside of us. According to studies, antibiotic-associated diarrhea can occur in 5% to 39% of individuals taking antibiotics, lasting up to two months after the treatment ends.
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The Effects of Antibiotics
The Center for Disease Control and Prevention estimates that more than 200 million antibiotics are prescribed each year. About 28% of all antibiotics prescribed are for infections that do not need them. Antibiotics are only helpful when combating bacterial infections, such as forms of strep or ear infections, and not viral infections, such as the cold or flu.
The life-saving impact of antibiotics in today’s society cannot be overstated. However, antibiotic overuse has become a global health concern with serious consequences, such as the emergence of antibiotic-resistant bacterial strains. Taking an antibiotic kills the bacteria in its way, including the helpful bacteria that helps protect the body from harmful bacteria. Although the extent that probiotics can aid in reducing the spread of antibiotic resistance is not conclusive and still under much investigation, existing research — such as a 2016 study, hypothesized that maintaining a balanced microbiota while taking antibiotics may aid in reducing the spread of antibiotic-resistant bacteria.
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What Are Probiotics?
To keep the gut microbiota as balanced as possible while taking antibiotics, many clinicians and dietitians recommend taking probiotics — live microorganisms that confer health benefits to the individual. The term probiotics is broadly used today to describe various “good” strains of bacteria, yeast, fungi and other microorganisms. Probiotics can be found in food and supplement form.
Your gut microbiota influences many essential functions from how you metabolize food, your immune response, breaking down and absorbing medicines and even the amount of certain neurotransmitters like dopamine and serotonin your body produces. The different species of probiotics in the gut microbiota vary by person and fluctuate based on factors such as diet and exercise, physical and mental stress, where you live, if you have recently been sick and how old you are.
Research has shown that these beneficial microorganisms are crucial to many body functions and therefore overall health, but there is much that is not understood about them and how they work. Studies are conflicting as to how beneficial probiotics are while taking antibiotics and what strains work best. One meta-analysis of 42 studies, published in the British Medical Journal in 2021, found that probiotics are effective for preventing antibiotic-associated diarrhea. A separate 2020 study in Frontiers in Cellular and Infection Microbiology noted that while some studies have shown positive effects of certain probiotics, most studies failed to report any impact on the microbiota.
There are certain strains, though, that have long-term, solid evidence behind their effectiveness for most people. Probiotics that are commonly recommended are the bacteria Lactobacillus rhamnosus GG, or LGG, and the yeast Saccharomyces boulardii.
“The evidence right now doesn’t necessarily suggest that these are the very best, but we have the greatest number of clinical trials that have studied these two strains and have found them to be beneficial in some circumstances,” Preidis says.
The strain S. boulardii is a yeast and therefore one to take during a course of antibiotics since antibiotics kill bacteria and not yeasts.
“There are studies showing there is a decreased prevalence of having antibiotic associated diarrhea or C. difficile when taking 250 milligrams twice a day of a probiotic called Florastor, which has a pharmaceutical grade strain of S. boulardii before and during a course of antibiotics,” says Dr. Gerard Mullin, an associate professor of medicine at Johns Hopkins Medicine in Baltimore.
The 2016 study in the Annals of Medicine showed that probiotics were observed to reduce the risk of certain secondary infections such as types of diarrhea and respiratory tract infections in those taking antibiotics and therefore reducing the need of another course of antibiotics for secondary infections.
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Probiotics and C. Difficile
One bug of particular concern after antibiotic use is Clostridium difficile, which can cause diarrhea, as well as more severe symptoms like inflammation of the colon that can be life-threatening. Antibiotics disrupt the normal balance of microbes in the gut and a decrease in microbe diversity allows the overgrowth of some pathogens like C. difficile. According to the CDC, people are 7 to 10 times more likely to get C. difficile when on antibiotics and during the month after. There is potentially more risk if the antibiotic course is longer than one week.
“We tend to consider C. difficile as an opportunist,” Preidis says. “When there’s a disruption of the microbiota that inhabit a healthy intestine, as occurs when antibiotics wipe out large populations of healthy gut bacteria, this creates an opportunity for C. difficile to thrive in that wide open niche, expand its population and secrete toxins that cause the person taking the antibiotics to become sick.”
Difficult to eradicate, C. difficile sometimes afflicts people in long-term and acute health care settings.
“It’s more common in elderly people who are receiving antibiotics in the hospital,” Preidis says. “But it can certainly happen to otherwise healthy people just taking an antibiotic that’s been prescribed for a seemingly benign condition.”
When to Take Probiotics
Research published by the American Gastroenterological Association in the August 2020 edition of the journal Gastroenterology suggests that taking probiotics could be beneficial for three different types of patients with or at risk of three gastrointestinal disorders. The strength of the recommendations is conditional, based on the available research. That means the beneficial effects probably outweigh any undesired effects, but the review panel was not confident enough to issue a strong recommendation.
“However, these guidelines are not a blanket recommendation to use just any random probiotic off the shelf; you’ll need to work with your health care provider to determine whether adding a probiotic makes sense for your situation, and if so, which one,” Preidis says.
Based on this meta-analysis, the AGA suggests that taking certain species or strains of probiotics could be helpful for these three types of patients:
— Adults and children taking antibiotics. The AGA concluded there’s some evidence that particular strains could be beneficial for this population. The organization has recommended certain strains of probiotics as being potentially helpful for preventing C. difficile-associated diarrhea but warned that people with severe illnesses or immunosuppression may choose to avoid probiotics due to lack of evidence.
— Patients who have had a specific surgery for a common complication of inflammatory bowel disease. Some people with severe chronic inflammatory bowel disease require surgery to remove the colon and leave in its place a j-shaped intestinal pouch that holds stool and allows the person to empty the bowels rather than by a colostomy bag. This pouch can become inflamed, a condition known as pouchitis. Some patients in this category may be advised to take a specific cocktail of probiotics commonly marketed under the brand names VSL#3 or Vibiome to prevent or treat pouchitis, the AGA recommends. This recommendation is based on very low quality of evidence. Of the four levels of certainty — high, moderate, low and very low, this is the least certain rating for a clinical recommendation.
— Pre-term, low-birthweight infants. The AGA also recommends probiotics for preterm, low-birthweight infants born at less than 37 weeks weighing less than 5.5 pounds. Researchers found that multiple strains or combinations of strains of probiotics in the lactobacillus or bifidobacterium genera can prevent necrotizing enterocolitis and death from all causes. NEC is an inflammatory condition that affects preterm infants at a high rate and often leads to death. The quality of evidence for this recommendation is moderate to high.
Sources of Probiotics
Probiotics can be found in food products and in supplement form, including capsules and powders that can be added to food and drink. To be effective, probiotics need something called prebiotics, which are fibrous compounds in food that the probiotics “eat.” These prebiotics will not only make any probiotics you take more effective, but just as importantly, they will help support the gut flora that you already possess. You can find prebiotics in supplement and food form.
Foods that provide prebiotics include:
While probiotic supplements are plentiful, they should be approached with caution.
“Supplements are a poorly regulated field, and you cannot always rely on getting what the label advertises,” Mullin advises.
Instead, experts encourage people to get their probiotics from real, whole foods.
“Yogurt, kefir, sauerkraut, kimchi and all of these fermented foods or probiotic-rich foods are important to have in our diet on an everyday basis,” says Jennifer McDaniel, a registered dietitian nutritionist based in St. Louis, Missouri.
Foods that provide probiotics include:
If you choose to go the probiotic supplement route, it’s important to consider dosages. Similar to how some drug doses are measured in milligrams, probiotic doses are measured in colony-forming units, or CFUs. The effective dose may vary from one probiotic to another. The microbes in probiotic products don’t stay viable forever; the number of CFUs the product has can diminish with time. Therefore, it’s important to check the expiration date of each product. It’s key to follow the instructions on the supplement to keep the bacteria or yeast viable.
Ask your health care provider which strain of probiotic is right for you and what dose (number of CFUs) you should look for because there’s more to it than just picking up any old probiotic supplement from the drug store. The term “probiotic” is as general as the term “vitamin,” which is to say that it’s only likely to benefit you if you take a species or strain and dose that has been specifically demonstrated to have efficacy for the issue you’re trying to address. For example, you wouldn’t take a vitamin D supplement to treat a vitamin B12 deficiency. Similarly, you’ll need to be precise with the dose and strain to get the benefit of a probiotic supplement.
“We want to make sure that you’re taking the right type of yeast or bacteria with your antibiotic,” McDaniel says.
Best Time to Take Probiotics
Although they’re often paired, experts typically advise against taking certain probiotics and antibiotics at the exact same time to try to reduce the probiotic bacteria killed by the antibiotic. If you’re taking an antibiotic in the morning and at night, it’s best to have the probiotic at lunch, Cullen says. (Remember, S. boulardii, a probiotic strain recommended by the AGA for C. diff prevention, is a yeast, not a bacterium and, thus, is not impacted by when you take it compared to antibiotics.) There are no accepted guidelines for when to take probiotics.
Because supplements aren’t tightly regulated like pharmaceuticals, what’s in a particular supplement may be different from what’s advertised. One 2019 study found that about two-thirds of products marketed as probiotics are species or strains with no demonstrated benefit to human health. Another study noted that mislabeling of products is rampant, with about one-third or more of probiotic products being misidentified at the genus or species level.
Though probiotics in food and supplement form have generally been found to be safe, be sure to work with your health care provider to determine if taking probiotics with antibiotics is the right combination for you.
This is particularly important because there are people with certain conditions who should not take probiotics. This includes individuals with a compromised immune system, like cancer patients receiving chemotherapy, or patients who have semi-permanent intravenous lines in their bodies.
Serious complications like sepsis, a potentially life-threatening infection, are extremely rare but do occur.
Additionally, people who take proton pump inhibitors — medications that are used for the prevention or treatment of acid-related conditions, such as ulcers and GERD — or otherwise have low stomach acid could potentially be at risk for developing small intestinal bacterial overgrowth (SIBO) as result of probiotic use, according to a 2018 study.
While probiotics show promise for people who take antibiotics, like for preventing C. difficile-associated diarrhea, experts say more research is needed to translate the evolving understanding of their effect into precise advice for patients.
“The quality of evidence supporting the use of probiotics for specific gastrointestinal disorders ranges from moderate to very low and is not strong enough yet to allow us to say with confidence that the beneficial effects outweigh any undesirable effects,” Preidis says.
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Antibiotics Can Mess With Your Gut. Here’s How Probiotics Can Help. originally appeared on usnews.com
Update 08/15/23: This story was previously published at an earlier date and has been updated with new information.
