Clinical trial for probiotics in irritable bowel syndrome fails to show efficacy

Irritable bowel syndrome is the most common functional gastrointestinal disorder, affecting about 10-15% of people in the United States alone, according to the International Foundation for Functional Gastrointestinal Disorders website. Fortunately, as described by the IFFGD, IBS is a functional disorder, meaning that while it does affect quality of life, it does not affect life expectancy. Probiotics have been studied as treatment for IBS because, as we’ve seen in many other examples of probiotic use, it is safe and rarely has any negative effects on the consumer. Some trials have shown that probiotics help relieve the symptoms of IBS; however the conclusions are controversial due to study structure and participant numbers. For this reason, scientists in Seoul, South Korea recently published a study in the Journal of Clinical Biochemistry and Nutrition, which studied the effects of a multi-species probiotic mixture on IBS symptoms using a double-blind study with a large number of participants.

Eighty-one patients participated in the 4-week-long double-blind study, with 42 people receiving a multi-species probiotic (containing Lactobacilli, Bifidobacteria, and Streptococci) and 38 people receiving a placebo. Baseline fecal samples were collected before probiotic/placebo consumption, revealing no significant difference between the two groups of participants. After consumption, the probiotic group showed a significant increase in concentrations of the probiotic bacterial strains in fecal samples, but not significant increase of levels of Bacteroidetes and Firmicutes.

In terms of symptom relief, while the probiotic group reported a greater percentage of relief, it was not significantly greater than the placebo group. This could be a classic case of the placebo effect, which is a phenomenon in which a sham treatment can actually improve symptoms because the person receiving the placebo believes it will help them. The results of this study are not concrete because there was no significant difference in symptom improvement; however there were significant increases in probiotic strains in fecal samples of the probiotic group. This study could be a step in the right direction toward relieving IBS symptoms.

Could ice cream prevent cavities?

We know that the oral microbiome hosts a wide variety of bacteria, some good, and some that cause cavities.  Those that cause cavities do so by producing acid as they break down the food in our mouths.  Researchers in India are trying to discover if probiotics could help alter the oral microbiome so there is a decrease in the bacteria that commonly cause cavities.  In their study they investigated a type of ice cream sold in India that has the probiotics Bifidobacterium bifidum and Lactobacillus acidophilus mixed in with the ice cream.  The researchers were interested in the effects the probiotic ice cream on the levels of bacteria and fungi in saliva, namely Streptococcus mutans, Lactobacillus acidophilus, and Candida albicans, because these three bacteria are the main causes of tooth decay.  The results were recently published in the Journal of Dental and Medical Sciences.

In the study, the researchers gave 20 participants one dish of ice cream each day for 10 days that either contained the probiotics or did not.  The researchers examined the bacteria in the participants’ saliva both before and after the ice cream intervention.  The results showed that consumption of probiotic ice cream caused a significant reduction of both S. mutans and C. albicans, and an increase in the number of L. acidophilus when compared to controls.  The increase in L. acidophilus is not surprising because the ice cream contained L. acidophilus. The researchers highlighted that in other studies of people eating Lactobacillus acidophilus, it did not persist in the individuals’ mouths.  Overall, two of the cavity causing bacteria decreased in abundance and one, which was in the probiotic ice cream, increased in abundance.

We must admit that the rigor of this study was highly lacking, so we don’t want anyone to take these results too seriously. While more research needs to be done to determine if probiotic ice cream can actually help prevent cavities and tooth decay, any study that recommends eating it is fine by me.  It’s obviously important to brush your teeth every day, but it’s definitely more fun to eat ice cream than to floss!