Previous studies showed that oleic acid-rich camellia oil (Camellia oleifera Abel., CO) alleviates the cognitive impairment symptoms of Alzheimer's disease (AD). Gac oil (Momordica cochinchinensis Spreng., GO) is rich in β-carotene, lycopene, and oleic acid; no study has explored the effects of GO on AD. Accordingly, this study examined the effects of GO and CO on AD prevention in rats subjected to AlCl3 intragastric gavage. The results exhibited similar effects of GO, CO, and GO/CO supplementation on restraining AlCl3-induced brain RAGE/NF-κB signaling, proinflammatory cytokines, MDA, and AD markers by upregulating anti-inflammatory cytokines, antioxidative enzymes, and autophagy, which subsequently enhanced the clearance of Aβ1-42 and memory capacity. Gut microbiota composition increased the proportions of short-chain fatty acids (SCFAs)-producing [Eubacterium]_coprostanoligenes_group and Lactobacillus_johnsonii in the oil intake groups, which were positively correlated with anti-inflammatory, autophagy, and dementia mitigation. This compelling evidence implies that consuming GO and CO is a strategy for AD prevention.