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One major issue with probiotics is that they often don’t stay in our system long enough to have a lasting impact. Research has shown that probiotics can either be flushed out of our system or only stay temporarily. For instance, a study on healthy individuals revealed two different outcomes: in one group, the existing gut flora resisted the colonization of foreign probiotics, a phenomenon known as “colonization resistance.” Essentially, these probiotics were expelled from the body. In the other group, known as “permissive individuals,” the probiotics were temporarily allowed to stay, but only during the period of consumption. Once they stopped taking probiotics, the beneficial bacteria could no longer be found in their gut (1).
There is a common belief that taking probiotics after antibiotics can help replenish the gut’s good bacteria. However, this is not always the case. One study divided participants who had taken antibiotics into three groups: one took probiotics, one received a fecal microbiota transplant, and one did nothing. The group that received the fecal transplant had their gut flora return to normal within days, whereas the probiotic group failed to recover their original gut flora even after five months. This suggests that probiotics can sometimes prevent the gut flora from returning to its normal state, especially following antibiotic treatment (2).
Another critical issue is publication bias within the probiotic industry. With the market for probiotics valued at around $77 billion (3), many studies on probiotics are sponsored by companies with a vested interest in positive results. A review of 34 reports found that 10 studies were assessed as high risk of publication bias (4). In another meta-analysis, an estimated total of 3,657 missing studies that were done but never reported (5).
Many times the researcher's hypothesis and the interests of sponsors, who favor the positive effects of probiotics, often lead to the non-reporting of negative results. Consequently, studies on probiotics exhibit significant publication biases. Even studies sponsored by probiotic companies may fail to disclose their sponsorship, further skewing the perceived benefits of probiotics (6). This bias means that the benefits of probiotics may be overstated, while negative results are underreported or ignored.
In some cases, probiotics can be harmful. In 2008, a randomized, double-blind clinical trial was conducted to assess whether probiotics could improve acute pancreatitis (7). Tragically, the study resulted in fatalities. Patients with acute pancreatitis were divided into two groups: 152 received probiotics, while 144 were given a placebo—an inactive substance usually composed of starch and sugar.
The results showed that 24 patients (16%) in the probiotic group died, compared to 9 patients (6%) in the placebo group. Additionally, 9 patients in the probiotic group developed bowel ischemia (restricted blood supply to the gut), and 8 of them died. No cases of bowel ischemia occurred in the placebo group. This led to the suspicion that bowel ischemia was a significant cause of death among those taking probiotics.
The study concluded that probiotics were actually harmful to patients with acute pancreatitis, with a mortality rate 2.7 times higher than those not taking probiotics. Therefore, it was determined that probiotics should not be administered to patients with acute pancreatitis.
While probiotics are marketed as beneficial supplements, their effectiveness and safety can vary widely. Business interests and biases may lead to skewed results and exaggerated claims about their benefits. Despite being promoted as essential, the benefits of probiotics are still not fully understood, as research in this area is still in its early stages.
Current studies on gut flora are just scratching the surface. While we recognize the importance of gut health, there is still much to learn about its complexities. Although probiotics are sold widely and are popular in the market, their long-term benefits remain uncertain.
No matter how many probiotic strains you consume, it pales in comparison to the number and variety naturally present in your gut. Buying probiotic products can create a false sense of security regarding health improvements.
To cultivate a healthy gut flora, focus on diet and lifestyle changes rather than relying on probiotics. A balanced diet and healthy habits naturally maintain a diverse and robust gut microbiome. This includes incorporating a variety of fermentable food substances, known as prebiotics, which nourish gut bacteria, promote their growth and diversity, and provide significant health benefits.
Remember, there are no shortcuts to good health, and it’s important to approach supplements like probiotics with a critical eye.
