An interventional study of rice for reducing cadmium exposure in a Chinese industrial town

Reducing cadmium (Cd) exposure in Cd-polluted areas in Asia is urgently needed given the toxic effects of Cd. The short-term and long-term benefits of lowering Cd exposure are unknown because of its long half-life in the body.

We aimed to investigate whether an intervention with low-Cd rice in a contaminated area of China reduced urinary Cd (UCd) levels and improved blood pressure and kidney function outcomes compared to no-intervention in consumers of high-Cd rice in the same region.

106 non-smoking subjects were divided into three treatment groups: the intervention group (replacing homegrown high-Cd rice with market low-Cd rice, n = 34), the non-intervention group (continue eating high-Cd rice, n = 36) and the control group (continued eating low-Cd rice they have been eating for years, n = 36). The intervention period lasted for almost 8 months, during which participants were visited on up to 4 occasions and UCd, systolic and diastolic blood pressure (SBP, DBP), kidney function biomarkers (β₂-microglobulin and N-acetyl-β-D-glucosaminidase) were measured.

After 3 months, the geometric mean UCd in the intervention (Int) group decreased significantly by 0.32 μg/g (p = 0.007), while changes were not significant in the non-intervention (non-Int) group (0.13 μg/g, p = 0.95) or the control group (-0.01 μg/g, p = 0.52). UCd in the Int group remained lower than in the non-Int group but higher than in the Control group through the end of follow up. DBP in the Int group decreased significantly from 80 mm Hg at month three (p = 0.03) and stayed around 74 mm Hg for the remainder of the study. SBP also decreased in the Int group but with variations similar to those observed in the other two groups. The two kidney biomarkers showed variations without a clear pattern.

This study suggested that UCd reflected both short-term (<3 months) and long-term Cd exposure. In addition, the low-Cd rice intervention showed initial benefits in lowering blood pressure levels, especially DBP, but not kidney biomarkers.