Background: Dementia is a neuropsychiatric disorder with cognitive decline due to multiple factors. With the arrival of the aging population, the incidence of dementia has gradually increased. There is still no effective treatment for dementia, and therefore, the prevention of dementia has become crucial. Oxidative stress is considered to be one of the pathogenesis of dementia; therefore, antioxidant therapy and prevention of dementia have been gradually proposed. Objective: Our meta-analysis aimed to investigate the association of antioxidants with risk of dementia. Methods: We searched PubMed, Embase, and Web of Science databases for articles on antioxidants associated with dementia risk, and those containing cohort studies with high-dose versus low-dose controls were included in our meta-analysis. The resulting risk ratios (RR) and hazard ratios (HR) and 95% confidence intervals were statistically analyzed using Stata12.0 free software. Results: A total of 17 articles were included in this meta-analysis. Of 98,264 participants, 7,425 had dementia after 3–23 years of follow-up. The results of the meta-analysis showed a trend towards a lower incidence of dementia with high intake of antioxidants (RR = 0.84, 95% CI 0.77–1.19 I 2 = 54.6%), but this was not statistically significant. High antioxidant intake significantly reduced the incidence of Alzheimer ‘s disease (RR = 0.85, 95% CI 0.79–0.92 I 2 = 45.5%), and we additionally carried out subgroup analyses by nutrient type, diet or supplement, region, and study quality score. Conclusion: Dietary intake of antioxidants or supplements reduces both the risk of dementia and the risk of Alzheimer’s disease.