Superfood rice bran contains arsenic

China has food standards for arsenic?
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Rice bran – a so-called "superfood" – might contain dangerous amounts of a natural poison.

A new study suggests that rice bran, the shavings left over after brown rice is polished to produce white rice grains, contains "inappropriate" levels of arsenic.

Andrew Meharg at the University of Aberdeen, UK, and colleagues found that the levels of arsenic in rice bran products available on the internet and used in food-aid programmes funded by the US government would be illegal in China – the only country in the world to have standards for how much arsenic is permissible in food.

Meharg's team are calling on the European Union and the US to follow China's example and update food standards for arsenic. Arsenic is a natural carcinogen, present in drinking water around the world including in Australia, the US and many developing countries.

In previous work, Meharg has shown that brown rice contains more arsenic than polished white rice (Environmental Science and Technology, DOI: 10.1021/es702212p).
Nutritional drink

In the new study, Meharg and colleagues purchased brown rice from China and Bangladesh and polished part of it in the same way that it would be to produce commercial white rice. They found that 1 kilogramme of brown rice contained on average 0.76 mg of arsenic in its toxic inorganic form. The rice also contained some non-toxic, organic arsenic. The polished white rice grains contained 0.56 mg inorganic arsenic per kg, whereas the rice bran contained 3.3 mg per kg on average.

On the surface, this appears to be good news: the bran shavings are usually discarded except in Japan, where they are used in traditional pickling recipes. But in recent years a number of rice-bran products have come onto US and European markets, mainly targeted at health-food consumers. They are labelled "superfoods": the bran is high in antioxidants, vitamins, mineral nutrients and fibre. Producers say it is the largest wasted agricultural food resource on the planet, with 60 million metric tonnes of it discarded worldwide each year.

Some companies have produced a powdered version with a long shelf life at room temperature. Mixed with water, these "rice-bran solubles" make a nutritional drink and have been distributed as food aid to malnourished children in Malawi, Guatemala, Nicaragua and El Salvador. There are plans to further expand the aid programmes in Latin America, India and the Caribbean.
Meharg and his colleagues purchased nine commercial rice-bran products online, including rice-bran solubles from NutraCea, a company that participates in food-aid programmes, and analysed their arsenic content. The products contained between 0.48 mg/kg and 1.16 mg/kg of inorganic arsenic. China recently updated its standards, and set the limit to 0.15 mg of inorganic arsenic per kg of food.