Yogurt with probiotics and honey boosts gut bacteria but no digestive or cognitive benefits

By Dr. Chinta SidharthanReviewed by Susha Cheriyedath, M.Sc.Aug 6 2024

In a recent study published in The Journal of Nutrition, a team of researchers at the University of Illinois Urbana-Champaign conducted a randomized, crossover trial to investigate whether the consumption of yogurt containing the probiotic bacteria Bifidobacterium animalis subspecies lactis along with honey had an impact on the probiotic enrichment, intestinal transit time, digestive health, cognition, and mood in adults.

Study: Honey Added to Yogurt with Bifidobacterium animalis subsp. lactis DN-173 010/CNCM I-2494 Supports Probiotic Enrichment but Does Not Reduce Intestinal Transit Time in Healthy Adults: A Randomized, Controlled, Crossover Trial. Image Credit: itor / Shutterstock

Background

Close to 25% of the population of the United States (U.S.) suffers from digestive problems, including abdominal pain, inconsistent bowel movements, and irritable bowel syndrome (IBS). Constipation, however, is more prevalent among older adults, not just in the U.S. but also globally.

Increased consumption of probiotics is generally recommended for improved digestive health. Studies have shown that probiotics containing the bacteria B. animalis subspecies lactis DN-173 010/CNCM I-2494 (referred to henceforth as B. animalis) can alleviate gastrointestinal symptoms and reduce the transit time through the intestine among adults between 18 and 75 years of age.

The consumption of fermented milk products such as yogurt containing B. animalis is also believed to improve mood, regulate sensation processing and emotions, and positively impact cognition. Additionally, honey is thought to aid the in vitro survival of probiotic microorganisms and is often paired with yogurt in many diets.

About the study

In the present study, the researchers examined whether this common food pairing of yogurt and honey enhanced the abundance of probiotics and improved the in vivo functional outcomes such as intestinal transit time, overall digestive health, cognitive function, and mood.

The study recruited healthy participants between 22 and 64 years of age with a body mass index (BMI) between 18.5 and 29.9 kg per m². The participants were also required to have normal vision with or without correction, have between three and six bowel movements a week, and reside close enough to drop off the fecal samples within half an hour of the bowel movement.

Individuals who were pregnant, allergic to either honey or dairy products, used tobacco, or had been diagnosed with gastrointestinal diseases such as ulcerative colitis, celiac disease, Crohn's disease, diverticulitis, IBS, and hepatitis were excluded.

The study was designed as a randomized, single-blinded, controlled crossover trial. The interventions lasted two weeks and were separated by a four-week washout period. The intervention consisted of yogurt containing B. animalis and clover honey, while the control consisted of heat-treated yogurt and sugar. The treatment and control products were matched in their consistency.

Fecal samples provided by the participants were used to extract microbial deoxyribonucleic acid (DNA). Following this, the variable 4 (V4) region of the 16S ribosomal ribonucleic acid (rRNA) gene was amplified using high-throughput sequencing to determine the bacterial composition of the samples. The sequences were used for taxonomic assignments and assessing probiotic enrichment based on the relative abundance of species.

Gelatin capsules containing a food dye were used to measure intestinal transit time, while questionnaires, seven-day records, and laboratory-based stool processing were used to assess digestive health. A range of validated questionnaires and tasks were employed to assess cognitive function and mood at different points during the study.

Results

The study found that consuming yogurt containing B. animalis and clover honey enriched the levels of the probiotic bacteria but did not impact in vivo parameters of digestive function, such as intestinal transit time, cognitive function, or mood.

The consumption of yogurt alone was found to enrich the levels of bifidobacteria. Even the consumption of heat-treated or pasteurized yogurt was found to increase the levels of bifidobacteria in the fecal samples marginally. However, the researchers believe that this could also have occurred if the yogurt was already contaminated with bifidobacterium DNA before ingestion or if some bifidobacteria had somehow survived the heat treatment and passed through the digestive system.

Furthermore, the researchers stated that the lack of any effect of the yogurt and honey intervention on the intestinal transit time could be due to the participants' relatively short intestinal transit times. However, the lack of a notable difference in intestinal transit time between the treatment and control groups indicated that the consumption of yogurt and honey did not significantly impact the movement of food through the intestine.

While the current study found that the consumption of yogurt and honey had no impact on cognitive function or mood, the findings from other studies on the subject have been conflicting. Furthermore, the improvements in cognitive function and mood due to the consumption of probiotics might be more apparent in a study population with noticeable mental health conditions.

Conclusions

Overall, the study found that consuming yogurt containing the probiotic B. animalis along with clover honey enriched the probiotic bacterial content in the gut but had no noticeable impact on digestive or cognitive function. Further studies among varied study populations are needed to examine the impact of probiotics on cognitive health.