Do Probiotics Work? Sometimes.

Among the hottest trends in health foods today is probiotics. The live organisms contained in various probiotic pills and powders are thought to promote a healthy bacterial presence in the gastrointestinal tract.

The importance of healthy gut flora has been well-studied and well-documented, but a question that has never been accurately answered is whether probiotics actually improve gut flora.

Recently, researchers from the Weissman Institute and the Tel Aviv Medical Center, both in Israel, designed a series of comprehensive tests to determine if taking probiotics actually boost healthy gut flora, and improve overall health.

Lead researcher Dr. Eran Eliav stated that although people have thrown tremendous support (and large amounts of money) into probiotics, the literature supporting their efficacy is not clear.

The authors completed two studies, both published in the journal Cell, and as expected, the answers were not as simple as we have been led to believe.

In the first study, the authors gave one group of participants probiotics, while the other group was given a placebo. Gut bacteria was assessed before the pills were first given, shortly after they were given, and two months after they were given.

The findings showed that among the people who took the probiotics, there were two distinct outcomes. Some individuals simply expelled the probiotics; in other words, taking them had no effect whatsoever. The researchers referred to this group as “resisters.” On the other hand, some individuals benefited from the probiotics, which successfully colonized their digestive tract. The team referred to this group as “persisters.”

What makes one person a resister and another a persister? Researchers found that each participant’s “gut microbiome,” the genetic material of the microorganisms in their gut, as well as the expression of those genes, determined whether the person could benefit from the probiotic.

The second study involved looking into the question of taking probiotics after antibiotic use. Since antibiotics destroy the bacteria in a person’s digestive tract, people often turn to probiotics to help replenish beneficial flora.

During this study, a group of people on antibiotics was split into three groups: one group had no intervention, a second group was given the same probiotic regimen as in the first study, and a third group had their original microbiome restored via autologous fecal microbiome transplant (aFMT), using bacteria collected from them before they started their use of antibiotics.

The researchers discovered that in the first group, the bacterial environment of the gut returned to normal after a few weeks.

Those who took standard probiotics had rapid recolonization of their gut bacteria. However, the probiotics’ prompt takeover of the gut flora prevented individuals from restoring their previous, pre-antibiotic bacteria balance. In fact, among this group, gut flora did not return to normal for several months.

The group that received aFMT saw a full reversal of the antibiotics’ negative effects very quickly. This personalized treatment led to a return to a normal, healthy bacterial environment in a matter of days.

The conclusion of the study was clear: contrary to the belief that probiotics can help reverse the damage to bacterial flora caused by antibiotics, it appears that they actually have an adverse effect, preventing gut flora from returning to a normal state for far longer than doing nothing.

At Hamilton Grove Healthcare and Rehabilitation Center, in Hamilton, NJ, we don’t believe in fads. Our care programs are designed specifically to meet the unique needs and interests of seniors and long-term care patients. We emphasize restorative care, maximizing each patient’s potential to regain and maintain function and mobility.

We foster an environment that is cheerful and enthusiastic, so residents truly relish and appreciate life.

Our outstanding Social Services team works hard to ensure that every resident thrives socially, emotionally, and spiritually.

We promote a culture of independence, crucial for emotional, social, and physical health. Residents are encouraged to choose their activity and meal preferences, and to perform tasks and activities as self-sufficiently as possible.

We carefully select, train and re-train our wonderful caregivers, who are especially sensitive to the needs of our long-term care patients. They treat residents with love, compassion, and dignity.

Read our reviews on,, and to hear what our residents and their families have to say.

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