Gluten-Free Diets: Healthy or Potentially Toxic?

Gluten-Free Boom May Have Serious Fallout

Hello. I'm Dr David Johnson, professor of medicine and chief of gastroenterology at Eastern Virginia Medical School in Norfolk, Virginia.

Is a gluten-free diet healthy or not? The answer is, perhaps not. In fact, a recent analysis^[1] from researchers at the Mayo Clinic in Rochester, Minnesota, suggests that there may be an accumulation of heavy metals, which is well known to have a related risk for toxicity.

Let's explore this a little further. The gluten-free market has become very much of a wave, if not a craze, in the United States. In 2006, the gluten-free market was estimated to be approximately $0.9 billion, whereas in 2020 'it's expected to be closer to $24 billion.^[2] It is also estimated that approximately 1% or less of the US population has celiac disease,^[3] so clearly that group alone is not responsible for why this market has grown so exponentially.

A sizable number of people come into my practice and tell me that they feel better on a gluten-free diet, or they think that it is healthy. This is in line with most Americans who, when surveyed, feel that gluten-free is a healthier diet.^[4]

We have recent evidence to suggest, at least from a cardiovascular standpoint,^[5] that this is not the case. It is no healthier than a standard diet, and it may in fact be somewhat harmful for other reasons, including the removal of a lot of dietary fibers that you would otherwise consume and the reliance on things like rice and seafood-type products. There is evidence to suggest that the latter group of foods potentially has higher levels of heavy metals.

A Toxic Diet?

Let's look at the recent study from the Mayo Clinic.^[1]

They used a national database and a health examination survey that is administered every year to focus on population data from 2009 to 2012. They took a dietary survey as well, finding that 11,000-plus patients were not following a gluten-free diet and 115 were. Interestingly, only 11 of those 115 actually had the diagnosis of celiac disease. This underlines what I said previously, that a lot of people following gluten-free diets do not necessarily need to due to celiac disease. They were not able to assess gluten-intolerant patients.

They looked at serologic testing and blood level testing of heavy metals. Patients following the gluten-free diet had significantly higher levels of cadmium, mercury, and, in particular, lead, which are all particularly related to heavy metal toxicity. These levels were not in the toxic range, though they were clearly different from the non–gluten-free-diet patients. They then assessed a randomly selected group (3901 not following a gluten-free diet and 32 who were) for urinary arsenic levels, which again were significantly higher. These were in the toxic range for patients following a gluten-free diet. Remember, arsenic goes back thousands of years as a component of traditional Chinese treatments and other types of medicines, but it is also well recognized as a poison. Arsenic level accumulation and heavy metal accumulation are potentially sequential.

Discussions With Our Patients

We have no idea what's going to happen with these over time. For the time being, though, I think we ought to have a healthy discussion with our patients on gluten-free diets that it may not be the best thing for them. Simply asking, "Why are you doing this?" may be a great foray into a conversation. We can ask them, "Do you really need this? It's not for health, and there may be some attributable harm."

These results certainly open our eyes to potentially new monitoring requirements in patients who require gluten-free diets, such as our celiac [disease] population, especially for arsenic.

The potential bioaccumulation of these heavy metals and toxins over time, and lifelong adherence to gluten-free diets, may have consequences. We just don't know what yet, but it's something we must be aware of.

Perhaps this is a caveat emptor ("buyer beware") situation, in that gluten-free may not necessarily be healthy. I would certainly involve a dietician in the discussions to make sure you have all of the micronutrients and vitamins balanced across the population of these gluten-free patients.

Again, this is an opportunity to ask our patients why they're doing this and whether they really need to. It is certainly not for good health. The bioaccumulation of heavy metals may be something that is a wake-up call for a lot of people. It certainly was for me. This opens up a lot of questions going forward, which I will leave for you to best address in discussions with your patients.

I'm Dr David Johnson. Thank you again for listening.

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