Probiotics After Antibiotics: Which Strains Have Been Studied

Antibiotics are good at their job, sometimes too good: along with the bacteria causing trouble, they can clear out many of the helpful ones living in your gut. So should you take a probiotic with antibiotics? Many people do, and the idea makes sense: help restore the kinds of bacteria the antibiotic knocked down. What makes the difference is which bacteria are in the capsule, and whether enough of them survive the trip to your gut.

Below, we’ll look at what antibiotics do to the gut, four probiotic bacteria worth knowing, why the amount and the capsule matter, and how to time a probiotic around your course.

Your large intestine is home to trillions of microbes, known together as the gut microbiota. Antibiotics are designed to act on bacteria, and most can’t tell the bacteria behind an infection from the ones that normally live in your gut. The result is a temporary shake-up: fewer kinds of bacteria, and more room for unwanted ones to grow.

A study of gut recovery in healthy adults¹ followed twelve healthy men for six months after a four-day course of three antibiotics. Here’s how their gut bacteria changed:

Bifidobacteria, one of the main families of helpful bacteria in the human gut, were among the groups that took the biggest hit. That’s why probiotics for this stretch usually combine Bifidobacterium strains with Lactobacillus strains, the other family most often found in probiotics.

Each of the four strains below has been chosen for a reason: it belongs in the human gut, it can handle stomach acid and bile, or it has been studied in people. Research on them looks at gut balance and digestion in general rather than at antibiotic courses specifically, but each one brings something useful to the weeks when the gut community is rebuilding.

HN019 is one of the most studied Bifidobacterium strains, and it’s the most direct answer to the drop in bifidobacteria described above. In a study of HN019 in older adults², people who took the strain had more bifidobacteria and lactobacilli in their stool than those who didn’t. In a dose-response study of HN019³, 100 adults with frequent digestive complaints took one of two amounts or a placebo for 14 days. Food moved through the gut faster at both amounts, and digestive discomfort came up less often.

Bifidobacterium longum is one of the first bacteria to settle in the human gut, and it stays a regular resident throughout life. It tolerates stomach acid and bile salts well, which helps it reach the intestines alive, and the Bl-05 strain has a long record of safe use.

Lactobacillus acidophilus naturally lives in the human gut and is found in traditional fermented milks such as kefir. The La-14 strain comes from a human source, and in lab studies it attaches well to intestinal cells, which is what lets bacteria settle in rather than simply pass through.

Lactobacillus plantarum comes from plants and is abundant in fermented foods such as olives and sauerkraut. In lab studies, the Lp-115 strain attaches strongly to intestinal cells, holds up in acidic conditions and survives bile at the levels found in the small intestine.

The amount. After antibiotics have thinned out the gut community, there’s a lot of ground to cover. A higher CFU count delivers more live bacteria with each dose, which is why many people choose a high-potency probiotic during and right after a course, then switch to an everyday one.

The capsule. Probiotics are living bacteria, and heat, moisture, oxygen and stomach acid can all reduce how many survive. An acid-resistant capsule slows their exposure to stomach acid, so more reach the intestines alive. Sealed blister packs protect them on the shelf.

All four strains above come together in BioPro 100 DF, the high-potency probiotic from Focal Evolve that Aduco carries. It provides 100 billion CFU per capsule, including 50 billion CFU of HN019, more than the amounts used in the HN019 studies above. Focal Evolve formulates it to help maintain a healthy balance of gut bacteria, support bowel regularity and the natural immune response, and support lactose digestion.*

The capsules are acid-resistant DRcaps™, and each one is sealed in a nitrogen-purged aluminum blister pack to protect the bacteria from heat, moisture and oxygen. The formula is vegetarian and free of dairy and gluten.

Whatever you decide about probiotics, finish the full antibiotic course you were prescribed. A probiotic doesn’t replace it.

If you take a probiotic during the course, a common approach is to space it a few hours away from each antibiotic dose, so the antibiotic has less chance to act on the probiotic bacteria. Your prescriber or pharmacist can tell you what makes sense for the antibiotic you’re on.

In the recovery study above, most people’s gut communities took about six weeks to come back close to where they started. That’s why many people keep taking a probiotic for a while after the course ends. How long is a good question for your practitioner.

Once the high-potency stretch is over, some people move to an everyday formula. BioPro 30 DF from Focal Evolve has the same four strains as BioPro 100 DF at 30 billion CFU per capsule, for daily maintenance. Follow the directions on the label or your practitioner’s advice.