Rice is a staple food in many cultures and comes in various types. But no matter if your rice is purple, wild, black, white or brown, they all share one common thing, and that’s arsenic. Compared to other foods, rice absorbs about 10 times as much toxic inorganic arsenic as other cereal crops.
This is mostly due to the way rice is grown in flooded rice fields, which makes it easier for the crop to absorb the carcinogenic compounds naturally present in the soil. And while we’ve known about arsenic toxicity thousands of years ago, there’s not much we know about the dangers of arsenic via rice consumption as it is a more recent development.
Some countries have set limits on exposure to inorganic arsenic through rice consumption, but many Asian countries (where rice consumption is high) have no such rules. Fortunately, for several years it’s been understood that the levels of inorganic arsenic in rice can be reduced in various ways, via washing or rinsing, or using different cooking methods. However, some of these can also lower the levels of nutrients in rice, which also isn’t desirable.
Now, researchers from the University of Sheffield say a new and simple way of cooking can make rice safer for consumption. To do this, a team from the school’s Institute for Sustainable Food investigated different rice-cooking methods to see which offered the best way of reducing arsenic while preserving nutrients.
They examined four processes, all of which involved cooking rice via the absorption method, using either unwashed rice, washed rice, pre-soaked rice, or parboiled rice.
Best Way to Cook Rice
When they analyzed the results, they found that the “parboiling with absorption method” (PBA) can remove over 50 percent of the naturally occurring arsenic in brown rice and 74 percent in white rice. More importantly, this simple cooking technique helped preserve the most amount of the micronutrients in rice such as phosphorous, potassium, magnesium, zinc and manganese.
To do this at home, the researchers say to bring water to a boil (four cups of fresh water for every cup of raw rice). Then, add rice and boil for another 5 minutes. Next, discard the water (which has now removed much of the arsenic that was in the rice), and add more fresh water (two cups for each cup of rice). Finally, cover the rice with a lid, and cook on a low to medium heat until the water has been absorbed.
“With our new method we are able to significantly reduce the arsenic exposure while reducing the loss of key nutrients,” says soil scientist Dr. Manoj Menon.
“We highly recommend this method while preparing rice for infants and children as they are highly vulnerable to arsenic exposure risks.”
The International Agency for Research on Cancer has classified arsenic as a Group 1 carcinogen. Arsenic exposure affects almost every organ in the body and can cause skin lesions, cancer, diabetes and lung diseases.
In rice, arsenic is usually found in the outer layer of bran, which makes it more of a problem in brown rice. White rice, which is milled and polished, contains less arsenic but also has fewer nutrients due to the milling process.
“For rice consumers, this is excellent news. There are genuine concerns amongst the population about eating rice due to arsenic. Previous studies have shown that cooking rice in excess water could remove arsenic but the problem is it also removes nutrients,” says Menon.
“Our aim was to optimize the method to remove arsenic while keeping maximum nutrients in the cooked rice. Our newly developed method, PBA, is easy and home-friendly so that everyone can use it. We don’t know the amount of arsenic in each packet rice we buy; even though brown rice is nutritionally superior to white rice as our data shows, it contains more arsenic than white rice. With our new method we are able to significantly reduce the arsenic exposure while reducing the loss of key nutrients.”
The study was published in the journal Science of the Total Environment.