How to Cook Rice to Lower Arsenic Levels

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

“Cooking rice in a high water to rice ratio reduces [toxic] arsenic content”—meaning if you boil rice like pasta, and then drain off the water at the end, you can drop arsenic levels in half. 50 to 60 percent of the arsenic gets poured down the drain, whereas the typical way we make rice, boiling the water off like in a rice cooker or pot, doesn’t help. Or, may even make things worse, if the water you’re using to cook the rice has arsenic in it too—a problem that exists for about three million Americans, as about 8% of public water supplies exceed the current legal arsenic limits.

But “[c]ooking rice in excess water [and then discarding] efficiently reduces the amount of [toxic arsenic] in the cooked rice.” Yeah, but how much nutrition are you pouring down the drain when you do that? We didn’t know, until now.

“Unpolished brown rice naturally contains [nutrients] that are lost when the bran layer and germ are removed to make white rice. To compensate, since the 1940s,” white rice has had vitamins and minerals sprayed on it to quote-unquote “enrich it.” That’s why cooking instructions for white rice specifically say don’t rinse it, and cook it “in a minimal amount of water.” In other words, “the opposite” of what you’d do to get rid of some of the arsenic. But brown rice has the nutrients inside, not just sprayed on.

For example, “[r]insing [white] rice [—like putting it in a colander under running water—] removes much of the enriched vitamins sprayed onto the [white] rice…surface during manufacture,” removing most of the B vitamins, but has “almost no effect on vitamins in whole-grain brown rice,” because it’s got the nutrition inside. Same thing with iron: rinsing white rice reduces iron levels by like three-fourths, but the iron in brown rice is actually in it; and so, rinsing only reduces the iron concentration in brown rice by like 10%. But rinsing didn’t seem to affect the arsenic levels; so, why bother?

Now, if you really wash the rice, like agitate the uncooked rice in water for three minutes, and then rinse and repeat, you may be able to remove about 10% of the arsenic. And so, this research team recommends washing, as well as boiling in excess water. But I don’t know if the 10% is worth the extra wash time. But, boiling like pasta and then draining the excess water does really cut way down on the arsenic, and while that also takes a whack on the nutrition in white rice, the nutrient loss in brown rice is “significantly less,” as it is not so much enriched as it is rich in nutrition in the first place.

“Cooking brown rice in large amounts of excess water reduces the [toxic arsenic] by almost 60% and only reduces the [iron] content by 5%,” but does reduce “the vitamin content of brown rice by about half.” Here it is graphically. A quick rinse of brown rice before you cook it doesn’t lower arsenic levels, but boiling it instead of cooking to dry, and draining off the excess water drops arsenic levels 40%. That was using like six parts water to one part rice. What if you use even more water, boiling at 10:1 water to rice? A 60% drop in arsenic levels.

With white rice, you can rinse off a little arsenic, but after cooking, you end up with similar final drops in arsenic content. But the iron gets wiped out in white rice by rinsing and cooking, whereas the iron in brown rice stays strong. Similar decrements in the B vitamins with cooking for brown and unrinsed white, but once you rinse white rice, they’re mostly gone before they make it into the pot.

What about percolating rice? We know regular rice cooking doesn’t help, but boiling like pasta and draining does. Steaming doesn’t do much. What about percolating rice as a radical rethink to “optimize [arsenic] removal”? So, they tried like some mad scientist lab set-up, but also just a regular “off-the-shelf coffee percolator.” But instead of putting coffee, they put rice, percolating 20 minutes for white, 30 for brown, and got about a 60% drop in arsenic levels using a 12-to-1 water-to-rice ratio. Here’s where the arsenic levels started and ended up. The squares are the brown rice; circles are the white.

So, raw brown may start out double that of raw white, but after cooking with enough excess water and draining, they end up much closer. Though, 60%, percolating at a 12-to-1 ratio, was about what we got boiling at just 10-to-1; So, I see no reason to buy a percolator.

But, even with that 60%, what does that mean? By boiling and draining a daily serving of rice, we could cut excess cancer risk more than half, from like 165 times the acceptable cancer risk, to only like 66 times the acceptable risk.

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• Cheyns K, Waegeneers N, Van de Wiele T, Ruttens A. Arsenic Release from Foodstuffs upon Food Preparation. J Agric Food Chem. 2017 Mar 22;65(11):2443-2453.
• Raab A, Baskaran C, Feldmann J, Meharg AA. Cooking rice in a high water to rice ratio reduces inorganic arsenic content. J Environ Monit. 2009 Jan;11(1):41-4.
• Gray PJ, Conklin SD, Todorov TI, Kasko SM. Cooking rice in excess water reduces both arsenic and enriched vitamins in the cooked grain. Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2016;33(1):78-85.
• Rahman MA, Hasegawa H, Rahman MA, Rahman MM, Miah MA. Influence of cooking method on arsenic retention in cooked rice related to dietary exposure. Sci Total Environ. 2006 Oct 15;370(1):51-60.
• Islam S, Rahman MM, Islam MR, Naidu R. Arsenic accumulation in rice: Consequences of rice genotypes and management practices to reduce human health risk. Environ Int. 2016 Nov;96:139-155.
• Specific writers unnamed other than Cahill MS. U.S. Food and Drug Administration. 2016. May 13, 2014 Arsenic in Rice and Rice Products Risk Assessment Report (Revised March 2016).
• Focazio MJ, Welch AH, Watkins SA, Helsel DR, Horn MA. U.S. Department of the Interior, U.S. Geological Survey. A Retrospective Analysis on the Occurrence of Arsenicin Ground-Water Resources of the United States andLimitations in Drinking-Water-Supply Characterizations. Water-Resources Investigations Report 99–4279.
• Carey M, Jiujin X, Gomes Farias J, Meharg AA. Rethinking Rice Preparation for Highly Efficient Removal of Inorganic Arsenic Using Percolating Cooking Water. PLoS One. 2015 Jul 22;10(7):e0131608.
• Carey M, Jiujin X, Gomes farias J, Meharg AA. Rethinking Rice Preparation for Highly Efficient Removal of Inorganic Arsenic Using Percolating Cooking Water. PLoS ONE. 2015;10(7):e0131608.

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Image credit: gosheshe via Flickr. Image has been modified.

Motion graphics by Avocado Video. 

• arsenic
• cancer
• carcinogens
• cooking methods
• grains
• heavy metals
• iron
• pasta
• rice
• vitamins