A recent study has found that brown rice may contain higher levels of inorganic arsenic compared with white rice, which may increase health risks for certain populations, particularly young children.
In the study, published in Risk Analysis, researchers from Michigan State University conducted a comprehensive analysis examining arsenic exposure from rice consumption in the United States, comparing brown and white rice varieties.
"Rice bran and brown rice are shown to have a higher arsenic content and inorganic arsenic concentration than the grain endosperm or white rice," reported study authors Christian Kelly Scott and Felicia Wu, of the Department of Food Science and Human Nutrition at Michigan State University.
Their analysis found that arsenic, a known carcinogen, accumulates differentially in rice plants, with higher concentrations in the outer layers (bran) retained in brown rice but removed during the processing of white rice.
The research revealed several critical points:
- In U.S.-grown rice varieties, brown rice contained an average of 48% inorganic arsenic (the more toxic type) compared with 33% in white rice.
- Children under 5 years of age were at highest risk because of their higher food consumption relative to body weight.
- Among infants aged 0 to 6 months in the “eaters only” subpopulation, estimated inorganic arsenic exposure from brown rice was 0.221 μg/kg bw per day, exceeding the previously recommended safe daily dose of 0.21 μg/kg bw per day proposed by the Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives.
- Among children aged 6 to 24 months in the same subpopulation, estimated exposure from brown rice reached 0.295 μg/kg bw per day.
"Because young children consume considerably more food relative to their body weights than adults, brown rice consumption in young children was found to more substantially increase foodborne arsenic exposures," the study authors noted.
The study compiled comprehensive data showing mean arsenic values in rice:
- U.S. white rice: 0.244 μg/kg total arsenic, 0.093 μg/kg inorganic arsenic
- U.S. brown rice: 0.278 μg/kg total arsenic, 0.138 μg/kg inorganic arsenic
- Global white rice: 0.231 μg/kg total arsenic, 0.136 μg/kg inorganic arsenic
- Global brown rice: 0.277 μg/kg total arsenic, 0.163 μg/kg inorganic arsenic
- Rice bran: 2.148 μg/kg total arsenic, 1.769 μg/kg inorganic arsenic (77% inorganic).
Rice bran, specifically, showed even higher concentrations at 2.148 μg/kg total arsenic with 1.769 μg/kg inorganic arsenic (77% inorganic).
Despite the elevated arsenic levels in brown rice, the researchers found that for most U.S. adults, daily inorganic arsenic exposure from rice consumption didn't appear to pose significant health risks.
"The daily inorganic arsenic exposure for most [U.S. adults] within the analysis did not rise to a level that was a concern to pose elevated risks of harmful health outcomes," the study authors stated.
However, they indicated the complex risk–benefit analysis involved in considering brown rice consumption, as brown rice provides higher micronutrient and fiber content compared with white rice.
The researchers called for additional research in three priority areas:
- A cost–benefit analysis of the public health implications of consuming brown vs white rice, considering both nutritional differences and food safety concerns
- Theoretical and ethical considerations around rice promotion discourse
- Analysis of policy impacts on rice farmers in response to the U.S. Food and Drug Administration's Closer to Zero action plan, which aims to reduce toxic elements in foods.
This research came at a time when brown rice has gained popularity as a “healthier” alternative to white rice, suggesting that nutritional messaging may need to incorporate potential arsenic exposure risks, particularly for vulnerable populations.
The authors have no conflicts of interest to report.