Arsenic and Mercury in Rice: New Research from Dartmouth CollegeTricia Thompson
February 28, 2018
Note: If you are a subscriber to Gluten Free Watchdog, summary test reports for both arsenic and mercury will be reposted with minor updates. Reposting these reports allows the entire community of current subscribers (and all new subscribers if they subscribe before May 28, 2018) to access this information regardless of subscription level (Watchdog or Premium). Please wait until you receive email notification that the reports have posted before trying to access them.
Updated summary test report for arsenic is available after login at https://www.glutenfreewatchdog.org/product/arsenic-summary-report-updated-2018/679
Updated summary test report for mercury is available after login at https://www.glutenfreewatchdog.org/product/mercuryricegrain-combined-data-2018-update-/680
The researchers from Dartmouth College who tested rice products for arsenic and mercury for Gluten Free Watchdog have just published a new article in the journal Food Chemistry entitled, “Essential micronutrient and toxic trace element concentrations in gluten containing and gluten-free foods” (abstract available at https://www.sciencedirect.com/science/article/pii/S0308814618301341). Among other micronutrients and trace elements, they assessed rice and rice-based products for arsenic and mercury.
Arsenic findings: Researchers found that “the total arsenic concentration in whole grain rice, rice flour and processed foods containing rice was significantly higher than non-rice flours and processed foods based on other grains.” In addition, brown rice and enriched white rice had significantly higher concentrations of total arsenic than white rice that was not enriched. The amount of inorganic arsenic was also significantly higher in brown rice than white rice—both enriched and unenriched varieties. According to the researchers, “inorganic arsenic accumulation in bran layers of the rice grain is a likely explanation for the higher inorganic arsenic concentrations measured in brown rice. However, the reason why enriched white rice grain contains higher organic arsenic concentrations than brown or non-enriched white rice is not clear and may be an artifact of the small sample size of each grain type.”
Mercury findings: Results were low for all foods tested, including rice. However, researchers found that “food containing rice had significantly higher mercury concentrations than those based on wheat or other grains.” Mercury concentrations did not differ significantly between rice types—brown, unenriched white, and enriched white.
Why does arsenic and mercury accumulate in rice? According to the researchers, “Like arsenic, the presence of methylmercury in rice is due to the practice of growing rice in flooded soils.”
Bottom line: Gluten Free Watchdog asked Tracy Punshon, one of the researchers for her main take away points from the study:
- Eat as wide a variety of gluten-free grains as possible
- Pay attention to the rice and rice ingredient content of gluten-free foods
At Gluten Free Watchdog we echo the above recommendations.
Thank you for this. I have been trying to get away from all the rice. I decided to really focus on it this year. I am doing much of what you have on your list. There are some really good recipes out there with millet flour and others that do not have rice in them. Rice seems to be the go-to flour/grain for GF products, but now that I am exploring the other options I am finding it pretty easy. Buckwheat makes a really good soup grain (try Moosewoods mushroom barley soup, substituting buckwheat and GF soy sauce). I discovered that millet is quite good; flour, grits and grain.
Also, for the crunchy crackers, I just bought Simple Mills Nut flour crackers at Costco, very good and no rice (nut flours, cassava, tapioca)
Thank you for your good work.
Joan – Be careful with too much Millet, it may not be good for your Thyroid
For folks with concerns about thyroid function, please read this article by my colleague Cheryl Harris, MPH, RD, “Thyroid Disease and Diet — Nutrition Plays a Part in Maintaining Thyroid Health” http://www.todaysdietitian.com/newarchives/070112p40.shtml
Consider Sorghum & Tapioca flour as alternatives.
Please make sure that naturally gluten-free grains, flours, and starches are labeled gluten-free.
Thank you Trisha,
After becoming gluten free, I began having nocturnal, grand mal seizures with vomiting. Long story short, it was the rice. Since cutting out rice, I no longer have the seizures except from some occasional cross contamination of rice. I don’t know if arsenic or mercury causes seizures, but whatever was in the rice sure made me sick as a dog.
A couple really good Gluten-Free, Rice-Free products:
Against the Grain Gourmet products: http://againstthegraingourmet.com/
RW Garcia 3 Seed Sweet Potato Crackers (Costco)
We need to start voting with our Gluten Free dollars by buying products that have NO rice flour!