Diet and Microbiome Interactions: Application in Posttraumatic Stress Disorder in Adults Consuming Vegetable Drinks

The gut microbiome has been shown to impact various facets of human health, including mental health. Studies have shown that populations with more agrarian lifestyles tend to have fewer chronic diseases and mental health issues than industrialized populations. A possible factor in these differences is the loss of co-evolved gut microbial taxa that has occurred with Westernization. This hypothesis, termed "Old Friends Hypothesis" suggests that the loss of certain gut microbes leads to immune dysregulation and increased chronic inflammation that contributes to development of cancers, cardiometabolic diseases and even neuroinflammation that can lead to negative behavioral and mental health outcomes. Other studies have shown that increasing the intake of plant foods may help increase diversity of the microbes in the gut and that this increased diversity could lead to better health outcomes in humans. The investigators propose to evaluate daily consumption of a drink consisting of a high diversity of plants (30 plant species) for four weeks on the diversity of the gut microbiome, biological signatures of inflammation, quality of life, sleep quality, and PTSD symptoms among persons with a diagnosis of PTSD. The investigators hypothesize that four weeks of daily consumption of this high plant diversity beverage (30 plant species) will increase gut microbiome ɑ-diversity, reduce markers of systemic inflammation, and improve PTSD symptom severity relative to daily consumption of a beverage containing only three plant species.

The intervention will be a double-blind parallel arm study that consists of a four-week treatment period where participants will be randomized to either the experimental or control arm of the study. During this four-week treatment period the participants will consume either a 4 oz beverage consisting of 30 different blended vegetables (high diversity treatment) or a similar control beverage consisting of 4 oz of blended Power Greens mix, containing only 3 different plant species (low diversity F\&V treatment). The participants will be asked to provide 2-day diet records every two weeks throughout the study. Participants will also complete daily bowel movement records using the Bristol Stool Scale (BSS) and collect 3 fecal samples (baseline, mid-point and final) that will be returned to the clinic at scheduled visits. Blood samples and gut, sleep, and mental health questionnaire data will be collected at the beginning and end of the study. Primary objectives are as follows: Objective 1: To determine whether consuming a higher number of plant types, thereby increasing exposure to diverse plant-associated microbes, increases gut microbial diversity. Specifically, investigators will use fecal samples from individuals before and after 4-week consumption of a 4 oz beverage made with high (30 different plants) and low botanical diversity (3 different plants) to assess taxonomic richness (CHAO) and diversity (Shannon) using 16s rRNA and metagenomic sequencing approaches. Objective 2: To determine how differences in plant diversity consumption influence inflammation and immune signatures, specifically plasma hsCRP levels and number/type of circulating T-regulatory cells. hsCRP will be assayed using ELISA and T-cells and other immune cells will be profiled from collected peripheral blood mononucleocytes (PBMCs) via flow cytometry. Objective 3: To determine whether gut microbial diversity and inflammatory profiles correlate with PTSD symptom severity. PTSD symptoms will be evaluated at each visit using the PCL-5 assessment and changes with treatment as well as correlates with other primary outcome measures will be determined.