Though making up just 0.01–2% of the microbiome, gut fungi play a key role in digestion, immunity, and metabolism. Species like Candida albicans and Saccharomyces cerevisiae influence nutrient absorption, while Kazachstania slooffiae aids carbohydrate breakdown. Factors like diet and age shape these fungal communities, and imbalances are linked to conditions like inflammatory bowel disease and obesity.