My research activities aim at developing a personalized holistic approach to promoting mental health in the elderly population. This approach combines personalized dietary recommendations based on the general information gathered from the individual (e.g., anthropometric measurements, dietary intake, medical history, quality of life) and their gut microbiome population. My research topic is also the mechanisms underlying the changes caused by personalized nutritional recommendations.
The gut microbiome consists of trillions of microorganisms and their genetic material in the intestinal tract. These microorganisms, mainly comprising bacteria, are involved in functions critical to health and wellbeing. They play a crucial role in food digesting. They are involved in many essential processes that extend beyond the gut, including body metabolism, body weight, immune regulation, brain functions, and mood. The gut-microbiome communicates with the brain through the gut-brain axis (GBA), which consists of bidirectional communication between the central and the enteric nervous system, linking emotional and cognitive centers of the brain with peripheral intestinal functions.
The type and amount of macro and micronutrients present in the diet (e.g., dietary fibers, omega-3, phytonutrients) have been widely found to influence the composition of the gut microbiota in the host. One of the main products of bacterial metabolism produced by the fermentation of dietary fibers is short-chain fatty acids (SCFAs), such as butyric acid, propionic acid, and acetic acid. SCFAs can stimulate the sympathetic nervous system, release mucosal serotonin, and influence memory and learning. In this context, diet manipulation of microbiota may influence behavior. The gut microbiota may alter nutrient availability and affect mucosal immune activation.
My main projects and their initial results are summarized below:
- The effects of personalized, diet-induced alterations in microbiota intervention on insomnia among older adults and to identify potential functional pathways (i.e., enhanced cognitive, motor, and mental functioning) underlying the relationship between nutrition and sleep (an RCT, in collaboration with The University of Haifa). Preliminary results show several associations between sleep continuity measures and specific gut microbiota. Furthermore, a dietary intervention was associated with improved sleep measures, gut microbiota abundances, and taxa changes.
- The associations between gut microbiota and geriatric depression, and the potential of a nutrition-induced microbiome personalized diet, aimed to improve quality of life and wellbeing in older adults (an RCT, in collaboration with the Shamir Research Institute). The results show that, after six months of a microbiome personalized diet, a significant reduction in depression symptoms was observed (expressed by a decrease in the Geriatric Depression Scale (GDS)). Moreover, older adults in the intervention group significantly increased their quality of life. According to the assessment tool developed by the World Health Organization (WHOQOL), older adults improved physical and mental health and increased social relationships after six months of intervention.
- Isolation and characterization of short-chain fatty acids, and their association to gut microbiota abundances, nutritional intake, and quality of life among elderly with insomnia. The results show that short sleep duration in insomnia (the most biologically severe disorder phenotype) is associated with increased fecal SCFA concentrations. These results are consistent with the idea that severe insomnia in older adults is accompanied by a chronic inflammation state, which may affect epithelial cells in the gut and decrease SCFA uptake. Since SCFAs are essential to gut cell function and brain signaling via neurotransmitters such as serotonin, reducing SCFA absorption by the gut cells is expected to affect sleep duration and continuity negatively. Furthermore, we showed that higher physical activity (expressed by a higher step count) was associated with less fecal SCFAs and specific microbiota and metabolite profiles in older adults with insomnia. Findings contribute to understanding pathways along the gut-brain axis and may lead to the use of SCFAs as biomarkers of insomnia. Results on topics (1) and (3) were partially presented in international conferences, and several scientific papers are being prepared for publication.
In addition, I am involved in developing an App based on the gut microbiome results and the scientific literature, which will give food suggestions to improve sleep and mood. (5) The development of a food-based supplement to help manage insomnia and depression symptoms.
My plans for future research are to (a) Explore the role of specific dietary patterns/food ingredients in neurobiological disorders (e.g., depression, anxiety) by performing clinical trials. (b) Study the effect of specific dietary patterns/food ingredients on the microorganisms present in the gut (e.g., their abundances, their metabolite concentrations). (c) The possible mechanisms that could explain the results (e.g., associations between blood markers, urinary and fecal metabolites with neurobiological disorder measurements).