Mercury and Arsenic Exposures in the Gluten-Free Diet: Finally A Silver Bullet for Unnecessary Use?

February 17th, 2017

Wow.  So I am rusty with blog stuff.  It’s been literally YEARS since I wrote a blog post.  When I started blogging, I wasn’t sure where I’d go with it.  I never pushed myself to make it a huge aspect of my life or career.  I figured if it was something I loved and was motivated to do, then it would organically become a part of my life. Time and interest proved I wasn’t that motivated.  That’s OK.  Tweeting and blogging are truly things I ONLY do if I really want to.  I think that’s the way most of our activities should be–why do something unless you really enjoy it?

That being said, this article came across my email this morning and I felt compelled to respond.  (It helps it’s Friday, my administrative day, where I have dedicated time for research).  The gluten-free diet is so misused, and the downsides of it are rarely highlighted, so anything that brings real pause for concern is truly important.

First off, some statistics.  About 0.7% of the U.S. population, or 1.8 million people, have Celiac Disease.  Celiac Disease is the ONLY real reason to be on a gluten-free diet.  I fully expect rants in comments regarding how “toxic” it is, but the fact is, there is no proof that gluten ingestion in the absence of celiac disease causes measurable long term harm.  Quite the opposite, in fact, are the numerous studies showing the harms of low carb diets and the benefits of whole grains (see below).  Studies showing benefit of low carb diets are almost exclusively limited to short term studies of less than a year’s duration and look at intermediate markers of health (like weight changes or blood tests) not true markers of health (like whether you live longer and get fewer diseases).

I do believe there are people who are gluten sensitive, and for those people, avoiding gluten makes them feel much better and makes sense.  However, in the absence of a proven sensitivity to wheat, there is no reason to be “going gluten free”.

There are many misleading very popular books that talk about how “evil” gluten is, but they are wrong.  They are simply factually inaccurate and misleading.  However, as our current political environment shows, people seem to respond more to drama, exaggeration and propaganda than actual facts.  For a quick, thorough, factual and medically sound rebuttal of the mis-information behind the evils of wheat, read this quick commentary by Dr. John McDougall, a physician who has studied the effects of diet on human health his entire career.

Moving on and back to my point about the significant downsides of the gluten-free diet, I know from experience that people don’t really care that the gluten free diet contains more saturated fat and sugar and less vitamins, minerals, and phytonutrients (plant nutrients) than a wheat-containing diet when consumed in the way most Americans are eating.  However, people who ~love~ the gluten-free diet MAY care if it contains more “poisons”, which is why I was really intrigued by this study in the journal Epidemiology published online this month. Here is the link to a media summary of the article:

Contrary to popular myth, the gluten-free diet is more likely to cause weight gain, not the opposite, which is ironic because so many people are “going gluten free” to lose weight.  The caveat is that the ill effects are predominantly seen in people basing most of their diet on processed gluten-free foods that use wheat flour substitutes.  That is, if you eat a lot of gluten-free cereal, cookies, muffins, etc, then you will by necessity ingest a lot of alternative refined grains, and many of those alternative refined grains have less vitamins and minerals *and possibly more toxins* than wheat itself.  Gluten-free eaters fair substantially better if they eat a gluten-free diet full of healthy fruits, vegetables, nuts, WHOLE gluten free grains (the key is WHOLE), and limited meat and dairy.

The researchers in this article were wisely concerned that the reliance on rice flour as a substitute for wheat flour in many gluten-free processed foods could represent a source of inorganic arsenic (the bad kind) and mercury.  We have known for a while that rice, particularly from certain regions like the United States, can contain higher levels of inorganic arsenic.  There is even an FDA advisory out regarding arsenic in rice, particularly in infant rice cereal.

The study referenced in the news article is well done and was conducted by researchers at universities with high integrity in science.  It was not easy to do because of the complicated statistics necessary to make it a valid and reliable study.  It is also important, VERY IMPORTANT, to know this is an OBSERVATIONAL CROSS-SECTIONAL STUDY NOT DESIGNED TO DETERMINE CAUSE AND EFFECT.  Why is that important?  Studies like this can be very helpful in looking for potential problems that need further evaluation.  Cause and effect studies like randomized trials, are EXTREMELY time consuming and expensive, so we can’t just go planning these on a whim.  Observational studies can be done with less resources and usually in a larger group of people to see if the problem is even worth looking into before we commit a lot of time and money getting to the real truth behind the story.

The study results are very simple:  Those who self-identified as eating a gluten free diet had more arsenic of all kinds, including inorganic arsenic, in their blood and urine.  Almost TWICE as much.  They also had higher mercury and cadmium levels (cadmium only in the urine).

Important things this study CANNOT show:

1. It cannot show whether eating a gluten free diet is the CAUSE of the higher levels  (see explanation above for cause/effect).

2. If the diet is causing the levels to be higher, it cannot show which aspect of the diet is the culprit (the assumption is that rice is the exposure, but they can’t know that for sure).

3. It cannot show whether the higher levels are causing or will cause health problems.

To determine those three very crucial points, we need more studies (whah whah, the disappointing but appropriate conclusion of observational research).

What do I take from this?  What I’ve always taken from the gluten-free diet:  The gluten-free diet is NECESSARY for celiac patients and POINTLESS for most everyone else.  Why would anyone choose a diet that has no measurable health benefit but is likely to cause harm?  I also think it is very important for patients with celiac disease to be aware of these issues and try to limit gluten-free processed foods.  Processed foods of all kinds are bad for health (in everyone, not just celiac patients).  Stick to veggies, fruits, nuts, and select healthy gluten-free whole grains.

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    About Me

    Professional Gastroenterology Fellow

    Amateur Martha Stewart/Bob Villa/Julia Child/Collette Peters