Increased Arsenic Exposure from Rice on the Gluten-Free Diet

Learn your risks... and what you can do to lower them

uncooked rice
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Plenty of people who follow the gluten-free diet rely on rice as their staple grain for a variety of reasons: it's inexpensive, it's readily available, and (perhaps most importantly) it's an ingredient in the majority of ready-to-eat gluten-free products like bread, cereal, cookies, and mixes.

But research increasingly is showing that those who eat lots of rice—such as those with celiac disease and non-celiac gluten sensitivity—may be at risk for consuming problematic levels of arsenic, a toxic metal that tends to accumulate in rice.

Additional research indicates that other so-called "heavy" metals—including mercury—also are found in higher levels in people who eat gluten-free.

The information on arsenic in those who are gluten-free is concerning, says Tricia Thompson, a dietitian and expert on celiac disease and the gluten-free diet. Thompson, head of the food testing service Gluten-Free Watchdog, tells Verywell that she has taken "a long hard look" at the data she and other researchers have compiled.

"I am convinced that inorganic arsenic intake among the gluten-free community is a serious concern and it deserves our attention," Thompson says.

Why Does Arsenic Accumulate In Rice?

You probably know of arsenic as a poison—in fact, it has a long history as a stealth weapon. But you may not realize that arsenic, in tiny amounts, exists all around us as a naturally-occurring part of our rock and soil, our water, and even our air.

Because arsenic exists in soil, plants growing in that soil can take it up and absorb it. Once they do this, they can't get rid of it easily, and so it tends to build up in the grain, which is the part of the plant we ultimately eat. The rice plant happens to be more efficient than most plants—including gluten-containing wheat, barley, and rye—at accumulating heavy metals such as arsenic.

That's why those who eat rice, such as people who don't eat gluten grains, may have higher levels of arsenic and other heavy metals.

There are two kinds of arsenic: organic arsenic and inorganic arsenic. Scientists agree that the inorganic type is more dangerous than the organic type. Unfortunately, this is the type that tends to build up in rice. Like the rice plant, our bodies are not very efficient at getting rid of toxic substances such as arsenic, so it tends to build up in us as well, and that can cause major health problems.

Arsenic in larger amounts can poison someone, but arsenic in smaller amounts is associated with a variety of different kinds of cancer, including skin, lung, bladder, kidney, and liver cancer. It's also associated with cardiovascular and neurological problems, and in fact can affect many different body systems.

It's impossible to avoid arsenic completely—again, it's in our soil, water, and air. Therefore, the U.S. Food and Drug Administration has set safety standards for the amount of arsenic that can occur in drinking water, and has proposed standards for other foods, including apple juice.

Gluten-Free Dieters at Special Risk for Arsenic Exposure

There's no doubt that many people following the gluten-free diet eat lots and lots of rice, in a variety of forms: A quick survey of the gluten-free aisle at the supermarket shows rice, in some form, as an ingredient of about three-quarters of prepared gluten-free grain-based foods.

So with the growing popularity of eating gluten-free, researchers have begun focusing on the levels of arsenic in both the foods and the people who eat them. Thompson is one of those researchers—she and a colleague surveyed people with celiac disease to see how much rice they ate each week in an effort to estimate their arsenic exposure.

The researchers found that people with celiac get their rice from a variety of places, including plain rice, rice-based gluten-free breads, and rice-based snack foods, and higher consumption may place them at risk for excessive arsenic consumption. "A hypothetical individual consuming median amounts from each category of product would consume 10 servings of rice products each week," the study concludes.

"Based on these rice consumption patterns some individuals with celiac disease may be at risk of consuming above the EPA reference dose for chronic oral exposure to inorganic arsenic."

Another study—this one from the Mayo Clinic—looked directly at levels of arsenic in people with and without celiac disease who were following the gluten-free diet. The researchers measured arsenic in the study subjects' urine and then compared results with levels of people not eating gluten-free, and found significantly higher levels in those who were gluten-free, regardless of whether or not they had celiac disease.

Mercury: Also a Problem?

Rice isn't just efficient at accumulating arsenic: it also can contain high levels of other heavy metals, including mercury and lead.

In fact, the Mayo Clinic study also performed blood tests to determine levels of mercury, lead, and cadmium, and found higher levels of all three in people on the gluten-free diet, regardless of whether they had celiac disease or not (the higher levels of cadmium didn't reach statistical significance in those without celiac who were gluten-free). Additional studies have backed up this research.

"Persons on a gluten-free diet have significantly higher urine levels of total arsenic and blood levels of mercury, lead, and cadmium than persons not avoiding gluten," the Mayo Clinic researchers concluded. "Studies are needed to determine the long-term effects of accumulation of these elements on a gluten-free diet."

This study doesn't prove rice is the culprit in heavy metal exposure for people eating gluten-free—other foods have high levels of these elements, too. For example, apple juice can contain higher levels of arsenic, and some fish carry too much mercury. However, another group of researchers found people with celiac disease had higher levels of mercury even though their fish consumption and number of mercury fillings were similar to those in a control group. So it's becoming clearer that something in the gluten-free diet is to blame, and rice is a primary suspect.

What Can You Do to Limit Your Risk?

Not everyone who follows the gluten-free diet eats lots of rice—people who tend to shun foods like bread and pasta should be at lower risk for this problem. But there's no doubt that those who have replaced conventional, gluten-y foods like bread and pasta with gluten-free versions may be consuming a lot more rice than they realize.

Thompson lays out some common-sense ideas for people who eat gluten-free and whose diets contain a lot of rice-based foods:

Folks following a gluten-free diet should consider: determining the arsenic level in their drinking water; assessing their intake of rice grain; sourcing rice from lower arsenic areas; cooking rice like pasta (in excess amounts of water); substituting quinoa or another gluten-free grain for rice grain; assessing their intake of rice-based products; and stopping the use of rice bran, rice milk, and rice syrup.

Some of these will be easier to do than others, obviously. For example, some research shows that cooking rice in lots of water and then draining the excess water can reduce the arsenic levels by 40 percent to 60 percent. Sourcing rice from areas that are lower in arsenic may be more difficult, since arsenic levels vary widely and it's not always obvious where your rice was grown. Well water can be high in arsenic, so if you get your drinking water from a well, you can purchase test kits that will show you how much arsenic is in your particular water.

But perhaps the simplest thing you can do to protect yourself is to substitute a variety of different gluten-free whole grains, such as quinoa or buckwheat, for rice in your diet. If you'd normally cook up a pot of rice to go with a stir-fry, for example, try the dish with another grain instead.

It's also possible to find gluten-free products—including cereal, pasta, bread, and cookies—that contain little or no rice. You'll obviously need to read labels to identify these products, but that's something people with celiac disease and non-celiac gluten sensitivity already know how to do.

Sources:

Eli L et al. Increased Mercury Levels in Patients with Celiac Disease following a Gluten-Free RegimenGastroenterology Research and Practice. 2015;2015:953042.

Food and Drug Administration. Arsenic in Rice and Rice Products fact sheet.

Naujokas MF et al. The Broad Scope of Health Effects from Chronic Arsenic Exposure: Update on a Worldwide Public Health ProblemEnvironmental Health Perspectives. 2013 Mar;121(3):295-302.

Raehsler SL et al. Accumulation of Heavy Metals in People on a Gluten-Free Diet. Clinical Gastroenterology and Hepatology. 2017 Feb 18.

Thompson, T and Jackson, B. Rice Consumption among US Adults with CD: Impact on Inorganic Arsenic Intake. International Coeliac Disease Symposium 2013 poster presentation.

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