by Chris Kresser

While having to take antibiotics is never ideal, there are many cases where it is absolutely necessary, and don’t worry – the situation is far from hopeless. It will take some time and effort, but there are many things you can do both during and after a course of antibiotics to minimize the damage and encourage regrowth and diversification of your gut flora.

Probiotics

To some, taking probiotics during a course of antibiotics might seem contraindicated. After all, won’t the antibiotics just kill all of the probiotics anyways? First, keep in mind that probiotics don’t need to actually colonize the gut to be beneficial; even transient strains can have powerful therapeutic effects. There are quite a few randomized, placebo-controlled trials that have demonstrated the effectiveness of probiotic use during a course of antibiotics for reducing side effects and preventing gut infection. (1, 2, 3, 4, 5, 6, 7)

For example, a study on 135 hospital patients taking antibiotics found that only 12% of the probiotic-receiving group developed antibiotic-associated diarrhea, compared with 34% of the placebo group. (8) Additionally, while 17% of the placebo group developed diarrhea specifically from C. difficile, nobody in the probiotic group did.

One interesting study tracked changes in gut bacteria in three different groups of people receiving antibiotics, with one group receiving placebo, one group receiving probiotics beginning after the antibiotic treatment ended, and the third group receiving probiotics both during and after antibiotic use. (9) The group receiving placebo had significantly higher levels of facultative anaerobes (their chosen marker for gut dysbiosis) 20 days after finishing antibiotics compared with baseline, while the two groups receiving probiotics had no significant difference. But even though both of the probiotic groups ended up back at baseline levels, only the group taking probiotics during as well as after antibiotic treatment maintained stable levels of facultative anaerobes throughout the experiment. In the group receiving probiotics only after completion of antibiotic treatment, facultative anaerobes increased significantly during antibiotic treatment, and decreased only after beginning probiotic supplementation. This clearly demonstrates the importance of taking probiotics during antibiotic treatment, as well as after.

Most of these trials used different strains of Lactobacilli, Bifidobacteria, or Saccharomyces boulardii. Lactobacillus and Bifidobacterium are two of the most common genera used as probiotics, so these supplements are readily available in most health food stores or vitamin shops. S. boulardii is actually a beneficial yeast rather than a bacteria, so it’s particularly useful during antibiotic treatment because the antibiotics can’t kill it. S. boulardii is also preferable under these circumstances because there’s no risk of it harboring genes for antibiotic resistance and later transferring those genes to pathogenic bacteria. (10)

Another option for probiotics is a blend of soil-based organisms, such as Prescript Assist. I haven’t located any studies on their effectiveness in conjunction with antibiotics, but based on my clinical experience, I believe they’re a great choice.

As with anything else, the best probiotic to take will depend on a person’s particular circumstances (such as the antibiotic they’re on and the state of their digestive system), but the two supplements I recommend most often are S. boulardii andPrescript Assist. If you don’t do well on either of those supplements or just wish to add more variety, feel free to add in a supplement with strains of Lactobacillus and Bifidobacterium. Do your best to take any probiotic supplement as far away from your antibiotic dose as possible.

Prebiotics

As I’ve mentioned before, prebiotics are much more effective than probiotics at promoting the growth of beneficial bacteria in the gut. Thus, prebiotics are an incredibly important part of any regimen to protect or rebuild a healthy microbiome. During and after antibiotic use, focus on getting plenty of soluble fiber, which feeds beneficial bacteria and is found in starchy tubers, squash, and peeled fruits. It might be best to avoid too much insoluble fiber while your gut is in a compromised state, since it can be irritating to the gut lining.

However, one type of insoluble fiber that can be extremely helpful for supporting healthy gut flora is resistant starch. (11) I’ve talked about resistant starch before here and here, and the easiest way to get a concentrated dose of RS is to use Bob’s Red Mill unmodified potato starch. As with any supplemental prebiotic, it’s a good idea to start with a small amount and work your way up. In this case, you could start with 1 teaspoon and work your way up to 2-4 tablespoons per day. If you find that RS doesn’t work well for you, you might consider trying an inulin-based prebiotic such as this one.

If possible, introduce any prebiotic supplements before beginning the course of antibiotics so your body can get used to them. That way, you won’t have to deal with possible side effects from introducing the prebiotic on top of possible side effects from the antibiotics.

Supporting diversity

As I mentioned in my article about the impact antibiotics have on gut flora, the main difficulty after a course of antibiotics isn’t recovering the number of flora present; it’s recovering the diversity. As we’ve seen, probiotic supplements can be incredibly helpful for preventing antibiotic-associated diarrhea and lowering the risk of a gut infection, and I recommend continuing with probiotic supplementation for a period of time after finishing your treatment. However, you can’t expect manufactured probiotic and prebiotic supplements to achieve the diversity of an ancestral microbiome on their own.

One of the best ways to expose yourself to more diverse beneficial bacteria is by consuming fermented foods, so I highly encourage you to experiment with a variety of different ferments. These can include kefir, beet kvass, sauerkraut, kombucha, kimchi, and other fermented vegetables or fruits. Keep in mind that foods like yogurt and kefir will probably only have a handful of bacterial strains if you buy them from the store, so homemade is best.

Another way to diversify the bacteria you’re exposed to is by gardening or otherwise getting your hands dirty, although I haven’t seen any research on whether that exposure translates to a more diverse set of gut bacteria.

As far as prebiotics go, just try to get as much variety in your plant foods as you can, in addition to supplementation with resistant starch or another prebiotic formula. Some of the best sources of soluble fiber include carrots, winter squash, summer squash (especially peeled), starchy tubers, turnips, rutabagas, parsnips, beets, plantains, taro, and yuca. Green bananas and unripe plantains (which you can dehydrate to make chips) are good whole-food sources of resistant starch.

Support for the gut and the liver

When antibiotics throw your gut flora into turmoil, the gut lining and digestive function as a whole take a hit too. To soothe your digestive system, it’s a good idea to ramp up your consumption of bone broth and other glycine-rich foods while you’re on antibiotics, and continue to consume these foods after the treatment is finished to promote healing.

If you experience nausea or other digestive upset from the antibiotics, ginger can be extremely helpful for reducing inflammation and calming the digestive system. (12, 13) It’s best to use fresh ginger, and you can easily make ginger tea by slicing it and simmering it in water until the tea reaches your desired strength.

Antibiotics can also take a toll on your liver, particularly if you’re on them for an extended period of time. Not only is the liver is responsible for processing and detoxifying medications, it also has to deal with extra circulating lipopolysaccharides from the increased bacterial death and intestinal permeability. Milk thistle is one of my favorite supplements for supporting liver health, and can be taken in a pill (like this one) or as a tea. (14, 15) Glycine is also important for liver detox, so be sure to drink that bone broth!

I hope you found this article helpful. As always, I’d love to hear from you in the comment section; just be mindful that I’m busy with my book tour right now, and may not be able to reply to your questions. But many of my readers are extremely knowledgable, and I encourage you to take advantage of the free forum in addition to the comments section to bounce ideas and experiences around.