Background and Purpose: The food-grade (fg) SiO2 is used as anticaking and antifoaming agent in powdered food (e.g., sugar, salt, milk, instant soup, infant formulae), with chronic dietary exposure in Humans (0.8-74 mg/kg bw/day). This food additive is composed of aggregated nanoparticles (NPs) that cross biological barriers, like the intestine and placenta, and accumulate in systemic organs raising public health issues. Following ingestion, SiO2-NPs could also alter the intricate dialogue linking the intestinal microbiota to various functions under its control, including the intestinal barrier, immune functions, and host metabolism, with health consequences. Through a longitudinal study from in utero life to adulthood in mice, the aim of this study is to explore the consequences of chronic oral exposure to fg-SiO2 on the microbiota-intestine-immune system axis, and on metabolic functions of the descendants. Methods: Female mice were exposed to a control or fg-SiO2-enriched diet at a human relevant level (10 mg/kg bw/day) during pregnancy and lactation until weaning of pups, then the descendants (F1) were fed the same diet as their mother until postnatal day (PND) 150. Intestinal permeability to macromolecules (oral FITC-Dextran 4kD) was determined in vivo at PND136 while oral glucose tolerance was assessed at PND143. At PND150, intestinal and systemic production of pro- and anti-inflammatory cytokines was measured by ELISA, and gut microbiota composition was assessed by 16S gene sequencing. All animal experiments were approved by the Local Animal Care and Use Committee. Results: Chronic fg-SiO2 exposure starting in utero increased the intestinal permeability and the production of the pro-inflammatory cytokines TNF-α and IL-6 and of the anti-inflammatory cytokine IL-10 in the colon of adult F1 males. In F1 females exposed to fg-SiO2 a decrease in TGF-β and an increase in IFN-γ secretion were observed in gut mucosa without intestinal permeability alteration. The systemic immune response following exposure to the food additive also differed between the sexes, with a decreased production of TNF-α, IL-6, IFN-γ, IL-17, IL-10 and TGF-β in males, while an increase in the secretion of IL-17 and TGF-β was found in females only. Changes in gut microbiota composition occurred in fg-SiO2-exposed males only, exhibiting increased β-diversity and decreased proportion of the Actinobacteria and of the species Akkermansia muciniphila and Bifidobacterium pseudolongum, both known to alleviate metabolic disorders. Accordingly, an increased glucose intolerance was observed in F1 males exposed to fg-SiO2, while no alteration of glucose metabolism was reported in fg-SiO2- exposed F1 females. Conclusions: These results showed that long-term exposure to fg-SiO2 from in utero life until adulthood initiate the development of metabolic disorders in a sexdependent manner via an alteration of the gut microbiota and of systemic immune response associated with gut inflammation and permeability in males only. This study provides new data relevant for risk assessment in pregnant women exposed to fg-SiO2 through their diet, and supports the establishment of toxic reference values for the safe use of SiO2 as food additive.