Is a Truly Gluten-Free Diet Possible?

There is no such thing as a truly gluten-free diet, says Daniel Leffler, MD, associate professor of medicine at Harvard Medical School.

Since the 1940s, doctors have prescribed a strict lifelong gluten-free diet as the only effective treatment for celiac. The cure might be too good to be true. Leffler says 30 percent of celiac patients have ongoing symptoms that compromise daily life. New research suggests patients who believe they are following a strict gluten-free diet commonly consume unsafe amounts of gluten. Accidental exposure leads many patients to avoid eating outside the home.

Leffler says, “We really mean gluten-restricted diet, but it is way too late to rebrand that.”

The level of gluten restriction that can be achieved is effective for many patients, Leffler says. However, experts have assumed that those who don’t get better must be cheating on the diet. What really prevents recovery is the near impossibility of avoiding gluten. It is invisible, hard to detect and ubiquitous in the food supply.

The 20-ppm standard

The U.S. Food and Drug Administration (FDA) requires foods labeled gluten free to contain less than 20 parts per million (ppm) gluten. This derives from a 2007 study finding people with celiac could safely consume 50 milligrams (mg) per day. No government agency in the world recommended eliminating gluten completely. It would be nearly impossible.


A recent investigation of gluten-free oat products by PepsiCo, Inc., and General Mills suggests the distribution of contamination makes it easy to underestimate under normal test protocol. While a given sample may test safe, an occasional serving is bound to contain a harmful amount of gluten.

“In reality, people are probably getting much more than 20 ppm more frequently than they think,” says Jocelyn Silvester, MD, of Boston Children’s Hospital.

New stool and urine tests can reveal how much gluten a patient consumes. Spanish company Biomedal developed the technology GlutenDetect. Consumers can buy it online, but it is not FDA approved.

Researchers have started using it to track actual gluten consumption of patients in clinical trials for new drugs. A 2018 study from California drug company ImmunogenX, Harvard University and Biomedal was published in The American Journal of Clinical Nutrition. It concludes celiac patients consume “on average, potentially unsafe levels of gluten,” averaging at least 200 mg per day while following a gluten-free diet. At the high end, between 3 and 19 percent of patients accidentally consume more than 600 mg of gluten on a given day.


Early adopters

Children appear to adopt a gluten-free diet more readily. Stool and urine studies from Spain and Harvard suggest young children on a gluten-free diet consume the least gluten, followed by teens, with adults consuming the most.

However, even children are getting glutened. A recent study from Massachusetts General Hospital found one in five pediatric patients has persistent gut damage detected by a follow-up biopsy.

Not all experts agree with the assessment emerging from research in Boston. Hilary Jericho, MD, who treats children and teens at University of Chicago, says, “85 to 90 percent of my patients, maybe more” make full recoveries and feel great on a gluten-free diet.

A University of Chicago study comparing child and adult patients confirmed what has long been suspected:


on a gluten-free diet, children are more resilient and recover faster. Jericho says all patients need a reasonable expectation about how quickly their symptoms will resolve.

“If the gut is healed and a patient is not showing signs of inflammation or malabsorption, then we are achieving our goal. I think it is possible to be gluten free to the extent that you need to,” Jericho says. “Most of the time in kids who are not recovering, it is because they are still consuming gluten and not identifying where it comes from.”

Jericho adds GlutenDetect can reveal the problem in difficult cases.

Distinguishing symptoms


Ongoing symptoms may result from other conditions co-occurring with celiac. Silvester contributed to a study of 105 new celiac patients at University of Manitoba in Winnipeg, Canada. Gastrointestinal symptoms improved but remained common one year after treatment, with 96 percent adhering to a strict diet. They reported accidental exposure less than once per month, mostly at restaurants and other people’s houses. Celiac symptoms were difficult to distinguish from functional disorders such as irritable bowel syndrome (IBS), which cause discomfort while damaging the gut lining. Follow-up data raise further concern but are not published yet.

“We are finding higher rates of persistent mucosal damage than we necessarily expected,” says Silvester. “We did a follow-up biopsy at 24 months. In these adult patients, about 40 percent have villous atrophy.”

Celiac flattens the villi, small projections on the gut lining, but they should regrow quickly on a gluten-free diet. Although ongoing symptoms can result from functional problems after the gut heals, Silvester says a key question for follow-up is whether patients are still getting gluten: “I think the answer is definitely yes.”


Unfair judgment

Leffler says, “What we have done historically, which in retrospect was completely unfair, was put 100 percent of the onus on patients: ‘If you can’t get this right, it is your fault, you are not being strict enough.’ That was never a realistic expectation. Even when people did everything they were supposed to do, they were still getting exposed.”

Patients who are sensitive to the smallest levels of gluten need something more than a doctor berating them, he adds.

The data show what everybody knows: Some adults have more restraint than others. This is as true of celiac patients as anyone else. The Spanish study revealed 60 percent of male celiac patients were eating gluten compared to 30 percent of women.


“The number of people who claim to be on a strict diet decreases with time,” Silvester observes from the Manitoba cohort. “It is just recognizing that gluten is everywhere and striking a balance. You can be hypervigilant but that is not necessarily going to be good for your overall health. Lots of people lead happy, healthy lives on a good-enough gluten-free diet. We just do not really know what a good-enough gluten-free diet is.”

Silvester says she is concerned that ongoing damage from gluten could cause nutrient deficiency. She sees this in some patients. In small children, anemia may impair cognitive development. During adolescence, calcium malabsorption can hinder bone growth.

“The longer-term question is, if these patients have ongoing inflammation, are they at increased risk for lymphoma?” says Silvester. “We do not understand the consequences of chronic, intermittent, low-grade gluten exposure.”


Patient burden

Emma Clerx, 21 and entering her senior year at Harvard University, was diagnosed with celiac at age 12. She recalls how she adapted to a gluten-free diet: “My mom created this big binder with research from the internet, different books and whatnot to learn how to identify gluten, how to go to the grocery store and navigate the gluten-free options.”

Though satisfied with her treatment, Clerx agrees that no diet can be 100 percent gluten-free: “It is not reasonable to have to think about every single ingredient that you put into your mouth every day.”

Clerx shadows Leffler at Beth Israel Deaconess Medical Center. She sees a need for additional drug therapy: “Nonresponsive celiac disease exists. The gluten-free diet does not work for everyone. On a broader level, the gluten-free diet can be burdensome financially and socially.”


For patients who are meticulous about the diet, it can become too restrictive and make them obsessive. That leads to other unhealthy habits, Clerx says.

Quality of life

In a survey by Beth Israel Deaconess Medical Center, patients reported a heavier burden of treatment for celiac than any other chronic illness except end-stage kidney disease. Celiac patients complained of difficulty following the diet, concerns about food costs, trouble eating outside the home and time limitations in preparing their own food.

Celiac patients are drilled on the importance of a strict diet to avoid possible but uncertain health complications. For some people who generally feel well but get very sick when exposed to gluten, the experience can be traumatic, says Leffler. “They wind up leading reclusive lives and not having the social freedom or travel freedom that people without celiac disease enjoy.”

“It is not a benign treatment,” Silvester says. “Still, right now we need people to strive for as gluten free as possible.”

“We have a much better food supply for celiac disease than we have ever had before,” says Leffler, indicating expansion of the food industry. “I find it hard to believe that we are going to be able to make another leap forward in safe food availability.”

Doing their best

“People with celiac disease, we cannot spontaneously go to a restaurant and order whatever we want off a menu, even if it is labeled gluten free,” says Rachel Begun, RDN, based in Los Angeles. She is a member of the scientific and medical advisory council for Beyond Celiac, a nonprofit advocacy group. “We cannot rush to the airport without thinking ahead of time about what we will eat. I cannot show up to a weeklong business conference without having had multiple conversations with the person who plans our meals. There is a lot more planning involved.”

Begun, diagnosed with celiac in 2009, says, “As a dietitian, as a chef, as somebody who has a food- service background, I went into the gluten-free diet thinking, ‘I am leaps and bounds in front of everybody as far as education. It will be relatively easy for me to eat out.’ Now I am almost 10 years into living gluten free, and I actually eat out less than I ever have because I know that the likelihood for exposure to gluten is high.”

Back to basics

Begun recommends learning basic cooking skills so people can prepare their own meals and entertain friends at home.

“Our society’s way of socializing revolves around meeting people out for food,” adds Begun. “That’s great, but for people who need to be cognizant of what they eat, doing social things that do not require food can be the answer. Go for a walk. Go for a bike ride.”

Clerx says she had to become comfortable discussing her needs with waitstaff in restaurants. It turned out to be harder than explaining it to a friend or teacher.

“One of the most important parts of working out gluten-free living on the college campus was meeting with the dining hall manager at the beginning of the year, which I did during the first week of school to talk about what are the options, how can I eat safely in the dining hall, avoid cross-contamination and find what I need,” says Clerx. They were accommodating, and she has not experienced any egregious errors.

Jericho describes hypervigilant adolescents as “really good” patients; they choose colleges based on those with good gluten-free options in their cafeterias.

Empowered and gluten free

Jericho adds many of her patients cope well: “Though it is very daunting and scary at diagnosis, these teens come to feel empowered by it. I am always impressed by my patients. It makes them stronger people. I think it helps them with other challenges that they face in life.”

“It is better to have occasional gluten exposures and be out enjoying life, being social, than to be at home avoiding gluten and being safe,” says Silvester. “As a society, people do not see eating as an activity that involves nourishing themselves. It is seen as a task, not necessarily something that is valued or an investment. People prioritize other activities over food. Therefore, they are not willing to spend time. You get what you put into things. Often, having celiac disease forces people to shift that balance.”

Van Waffle is a freelance journalist in Waterloo, Canada, and research editor for Gluten-Free Living. He blogs at

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