Fried Soybean Oil Causes Systemic Low-Grade Inflammation by Disrupting the Balance of Gut Microbiota in Mice

Previous reports have mainly investigated the long-term effects (>30 d), such as gut microbiota dysbiosis and systemic low-grade inflammation, in mice fed fried oil. However, short-term intake of deep-fried oil is more likely to occur in daily life, and such studies are lacking. This study aimed to investigate the short-term effects of fried oil intake on systemic low-grade inflammation. Male Kunming mice were fed non-fried soybean oil or low (25%), medium (50%), or high (100%)-fried oil at 4.4 g/kg for 6 d. Serum and fecal samples were collected on day 7. In all groups fed fried oil, the serum levels of tumor necrosis factor (TNF-α) were significantly elevated 2-4-fold. Among the gut microbiota, the abundance of Alloprevotella significantly decreased by up to 76%, while Lactobacilli significantly increased by up to 385%. The fecal valeric acid content was significantly increased and positively correlated with TNF-α levels. Both valeric acid and TNF-α levels were positively correlated with the abundance of Lactobacilli and negatively correlated with that of Alloprevotella. In summary, a short-term ingestion of even low doses of fried oil alters the gut microbiota Alloprevotella and Lactobacilli and increases fecal valeric acid content, which correlates with increased serum TNF-α levels.