S778 Elemental Diets Do Not Induce Fungal Overgrowth in Vitro and Reduce Fecal Candida albicans in Humans

Introduction: Elemental diets (EDs) are complete sources of nutrition used in several gastrointestinal disorders, characterized by low fat content, free amino acids, and carbohydrates as the primary source of energy. Although EDs beneficially modulate the gut bacteriome with associated symptom improvement, their effect on gut mycobiome remains unknown. We assessed the potential for in vitro overgrowth of common pathogenic fungi when exposed to elemental diets and their key fat and carbohydrate macronutrient components. Additionally, we assessed changes in the Candida albicans before and after 2 weeks of exclusive ED from a human clinical trial (NCT05978973). Methods: C. albicans and Nakaseomyces glabratus were cultured in Sabouraud dextrose broth (SDB) at 37°C for ∼16 hours, then standardized to 10⁶ CFU/mL in phosphate-buffered saline (PBS). 100 uL of this suspension was incubated with a 100 uL of 2 commercial elemental diets (Vivonex Plus and mBiota Elemental), a dextrose-free ED, SDB+ maltodextrin (64%), SDB+ dextrose (13%), SDB+ maltodextrin+ dextrose, SDB+MCTs and SDB alone (+control). After incubation for 24 hours, samples were diluted, plated on SD agar and incubated at 37°C for 24–48 hrs. Colony forming units (CFUs) were then counted. Adult subjects with microbial overgrowth (n = 30) consumed 2 weeks of exclusive eucaloric oral palatable ED (mBIOTA Elemental) and were followed for 2 weeks upon reintroduction of regular diet. Stool DNA was extracted, sequenced and analyzed after PED. Results: Neither of the EDs tested induced overgrowth of C. albicans or N. glabratus (Vivonex Plus P = 0.20, P = 0.64 and mBiota Elemental P = 0.39, P = 0.64). Similar results were observed when C. albicans and N. glabratus were incubated with SDB supplemented with dextrose (P > 0.99 and P > 0.99, respectively) maltodextrin (P > 0.99 and P > 0.99, respectively), combination of these 2 sugars (P > 0.99 and P = 0.43, respectively) and dextrose-free ED (P = 0.22, and P > 0.99) when compared to the positive control. SDB+ MCT oil also appeared to modestly reduce the C. albicans growth (P = 0.009). In the human trial with PED, fecal C. albicans absolute load decreased by 3.3-fold (P = 0.04) after 2 weeks of the palatable ED. Conclusion: EDs and their macronutrient components do not promote fungal overgrowth in vitro and may reduce Candida burden in vivo. Further studies are needed to evaluate host-specific factors in diverse patient populations.