Worried about arsenic in your rice? Try this simple kitchen hack: According to an experiment that aired this week on the BBC show Trust Me, I’m a Doctor, soaking rice overnight and cooking it with extra water can reduce levels of the carcinogen by up to 82%.
Experts say this cooking method is a simple way to limit exposure to arsenic, which may be especially dangerous for pregnant women, children, and anyone who eats a lot of rice.
Arsenic is a naturally occurring element that’s present in soil and can make its way into drinking water, wine, and food crops. Because of the way it’s grown, rice has levels of arsenic 10 times higher than any other dietary staple, says Andy Meharg, PhD, a professor of molecular biosciences at Queens University in Belfast, Northern Ireland.
A 2014 Consumer Reports study detected arsenic in every one of the 233 samples of rice and rice-based products tested. It also found that people who ate a serving of rice had 44% higher levels of arsenic in their urine than those who hadn’t.
One form of the element, inorganic arsenic, has been linked to cancer and other health problems in humans. (The other form, organic arsenic, is less toxic but still concerning.)
To see if preparation technique affected the amount of arsenic in rice, Trust Me, I’m a Doctor invited Meharg, who’s been researching arsenic in food for years, onto the show. Meharg and host Michael Mosley found that when they cooked one part rice with five parts water, only 43% of the arsenic originally detected in the rice remained. And when they soaked the rice overnight and then used the 1:5 cooking method, only 18% remained.
Soaking rice opens up the grain’s structure, and allows arsenic, which is water soluble, to permeate into the liquid, Meharg explains. Arsenic also escapes into water while cooking, but if all of the water evaporates (as it does during the usual methods of cooking rice), the arsenic is absorbed back into the grains.
After you soak the rice, it’s important to drain and rinse the grains thoroughly with fresh water, says Meharg, and to cook them with fresh (and arsenic-free) water. Then, cook until tender—making sure the rice doesn’t boil dry—and rinse one last time with hot water before serving.
In his research, Meharg has found that batsami rice tends to contain less arsenic than other types, and brown rice tends to contain more. And because arsenic occurs naturally, buying organic doesn’t generally help. Arsenic can also be found in rice milk, rice cakes, and rice crackers, at even higher levels than cooked rice, he says.
Medical groups like the World Health Organization and the United States Food and Drug Administration have concluded that people who consume high amounts or rice have reason to be concerned, says Meharg. “In any case, if you can reduce exposure to a known carcinogen, you should,” he told Health.com via email. “This is just common sense.”
Exposure is particularly concerning for pregnant women and young kids, he adds, because even small amounts of arsenic have been associated with lower IQ and impaired development in children.
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Margaret Karagas, PhD, an epidemiologist at Dartmouth University, agrees that soaking rice and cooking it with extra water is a smart strategy for consumers, but says that finding ways to keep arsenic out of rice and other food products in the first place is still an important concern.
Karagas, whose own research has reported on arsenic in rice-based baby food, says that health impacts have been associated even with relatively low concentrations, and that there “don’t appear to be safe levels.”
“So, it is important to minimize exposure,” Karagas told Health.com in an email. Besides cooking with water, she added, “testing private wells for arsenic, and eating a diverse diet are other ways of reducing exposure.”