What makes for a happy tummy? A lot, actually.
As we now know, the microbiome within our digestive system teems with a diverse array of microbes, including bacteria, fungi, and even some protozoans and viruses. Not surprisingly, as research has tied the health of our microbiome to everything from inflammation and our immune system to our mental state, conversations about how prebiotics and probiotics might keep the trillions of microorganisms in our gut in check have also increased.
But what exactly can prebiotics and probiotics do for the gut?
What Prebiotics and Probiotics Do for You
“Prebiotics are something that feeds the bacteria in our gut. Probiotics, on the other hand, are the healthy bacteria that you want in your gut,” says Dr. Lela Altman, N.D., who runs a private practice in Seattle, and supervises digestive wellness services at the Bastyr Center for Natural Health.
According to Altman, you can get prebiotics through dietary supplements, such as psyllium and others designed to give you more fiber. They can also be found in foods such as plant fiber, vegetables and grains. Because these are hard to digest, they don’t completely break down, and leftovers become food for bacteria.
“Sometimes you know your gut bacteria is low from doing [medical] tests. Or if you are taking probiotics after a course of antibiotics, you might want to take prebiotics to help grow the bacteria population,” Altman explains. Like prebiotics, probiotics are available in supplement form, or you can get a daily dose in fermented foods and drinks, such as sauerkraut, kombucha, kimchi or tempeh.
“Generally, fermented foods have a beneficial effect on the gut. I recommend you make fermented foods part of your diet for a variety of probiotic organisms,” she says.
Yet, Altman cautions, the more we learn about our gut and the microbiome, the less we know. Where researchers once thought we could simply take probiotics to colonize or recolonize the bacteria in the gut, it is now understood that this isn’t exactly how probiotics work.
“Probiotics may colonize our gut for a short period of time, but they don’t actually change the makeup of the gut flora long term,” Altman says.
Researchers do believe, however, that specific strains of probiotics affect how bacteria in the digestive-system lining associate to improve performance and health in the gastrointestinal tract. “Bacteria communicate with one another through quorum sensing [a natural process where bacteria regulate their density and behaviors], and that may be what probiotics are doing; they may aid or change the way in which bacteria are communicating with one another,” Altman explains.
What to Look for in a Probiotic
When buying over-the-counter probiotics, Altman warns that not all products are what they say they are and that many are contaminated with heavy metals. She also discourages buying online versus at a reputable market where you can ask questions of a supplements expert.
Whether you are looking for prebiotic or probiotic products, Altman recommends seeking a quality brand that has been through third-party quality-control testing. This gives an added check to ensure that you are taking what you think you are taking.
For probiotics specifically, Altman suggests looking for the following three parts in a name: the genus, species and strain. Two common genus types are Lactobacillus and Bifidobacterium. After the genus is the species, such as acidophilus. Lastly, there should be a number or the strain, which is a subtype of the species.
For instance, with the probiotic Lactobacillus acidophilus HA-122, which is often taken after use of antibiotics to counter vaginal yeast infections or bacterial overgrowth in the intestines, Lactobacillus is the genus, acidophilus is the species, and HA-122 is the strain.
“I like to see the specific strain number. If it doesn’t show a strain number, I don’t trust it as much,” Altman says. “Current research is looking at strain numbers. When I prescribe products, I usually prescribe a specific strain or species for a condition.”
When recommending a probiotic, Altman typically suggests one with multiple strains. “I like to see at least five strains in a probiotic. That way it covers more of a broad area for each individual person. If we don’t know specifically what you will respond to, the more variety you have, hopefully one will work or be useful.”
The other piece of information Altman says to look for are the number of colony-forming units or CFUs. “I prescribe a range between 5 million and 10 million CFUs. We see products that are high-density—50 billion, 100 billion, even 300 billion. I don’t necessarily think it’s a good thing. I don’t think the more the better.”
When and How to Take Probiotics
Timing-wise, Altman recommends taking probiotics with meals, because food dilutes stomach acid, which can kill the probiotic. The key before taking prebiotics or probiotics, Altman cautions, is to make sure neither one is making a digestive issue worse.
For instance, small-intestinal bacterial overgrowth (SIBO), a common digestive issue, is caused by too much bacteria in the small intestine. Taking a prebiotic will only be feeding bad bacteria; likewise, there is a chance a probiotic will also make it worse.
“With SIBO, it’s not necessarily that you have the wrong bacteria; you have too many in the wrong spot. The small intestine should not have a lot of bacteria, as that is where you are absorbing your nutrients. If you have a lot of bacteria, it will steal your food and cause gas and bloating or diarrhea,” explains Altman, adding that “some people with SIBO do well with probiotics; some do poorly. It depends on the strain.” Altman suggests starting with a low number of CFUs, until you can assess if probiotics will aggravate or help your condition.
For general digestive troubles, such as diarrhea, gas or bloating, or after having food poisoning or taking antibiotics, Altman says it’s worth trying probiotics. She suggests taking general gut probiotics, containing various genus species of either Lactobacillus or Bifidobacterium. If you are having more consistent or serious digestive issues, Altman recommends consulting with a health professional first.