Studies have shown the association between metal exposure and various diseases in humans. Among exposure pathways, dietary intake is an important contributor. In China, studies have shown elevated As, Cd, and Pb concentrations in dietary staples, including rice, wheat, and vegetable, threaten human health. Assessment of metal intake from food consumption is important to assess the associated health risk. However, dietary metal intake is often calculated using total concentration in foods without considering metal bioavailability. There are limited reports of metal bioavailability in foods, with the importance of incorporating metal bioavailability into human exposure assessment not being considered. In addition, the major factors that influence metal bioavailability in food matrices have not been evaluated, which help to develop mitigation strategies to decrease metal exposure in humans. We collected rice, wheat, and vegetable samples from markets across China, and from two contaminated sites of Yixing, Jiangsu and Chenzhou, Hunan. In vivo mouse bioassays were developed and applied to measure As, Cd, and Pb relative bioavailability (RBA) in food samples, which was incorporated into daily metal intake estimation and compared to internal metal exposure such as urinary and hair metals. Factors that contributed to variation in metal bioavailability among samples were identified, while the influences of mineral dietary supplements on metal relative bioavailability in rice was assessed. For rice samples from markets across China and contaminated sites, an in vivo mouse urinary As excretion method was developed to measure As-RBA. Overall, As-RBA in rice from both markets (44.5–87.5%, n=14) and contaminated sites (11–65%, n=11) varied considerably, with As speciation being the dominant contributor to the variability. As-RBA was positively correlated with inorganic As, but negatively correlated with organic As. To measure Cd and Pb RBA in food samples, an in vivo mouse liver and kidney assay was developed. Similarly, Cd-RBA varied considerably in rice (16.9–57.4%, n=10), wheat (37.4–67.6%, n=8), and vegetables (17.7–78.0%, n=6) from the Yixing site. Also, Cd- and Pb-RBA in rice (n=11) from the Chenzhou contaminated site were 41–84% and 11–59%. For residents living in the Yixing site, the predicted urinary Cd based on total Cd in rice was 3.5 times that of measured values, while incorporating Cd-RBA to assessing rice-Cd intake made the predicted and measured urinary Cd more closer, suggesting the importance of Cd-RBA in controlling Cd exposure. Subsequently, we determined the effectiveness of mineral dietary supplements to modulate Cd exposure, revealing that Ca dietary supplement was the most effective way to decrease Cd-RBA in rice, while high dietary intake of chloride could enhance Cd-RBA. Future population-based intervention studies should be conducted to show the effectiveness of dietary mineral supplement to decrease human Cd body burden. For residents living in the Chenzhou site, As, Cd, and Pb exposure via rice consumption was compared to that via housedust ingestion based on RBA. Interestingly, we observed that for adults, rice was the main As contributor, while housedust ingestion was the major As contributor to children. However, for both adults and children, rice was the main source for Cd exposure, while housedust was the predominant Pb contributor. This was confirmed by overlap of stable Pb isotopic composition between Pb in housedust and hair from residents, while Pb signals in rice was different from housedust Pb.