Gluten-Free Diet What You Need to Know

Eat no wheat.

That is the core, draconian commandment of a gluten-free diet, a prohibition that excises wide swaths of American cuisine — cupcakes, pizza, bread and macaroni and cheese, to name a few things.

For the approximately one-in-a-hundred Americans who have a serious condition called celiac disease, that is an indisputably wise medical directive.

Now medical experts largely agree that there is a condition related to gluten other than celiac. In 2011 a panel of celiac experts convened in Oslo and settled on a medical term for this malady: non-celiac gluten sensitivity.

What they still do not know: how many people have gluten sensitivity, what its long-term effects are, or even how to reliably identify it. Indeed, they do not really know what the illness is.

The definition is less a diagnosis than a description — someone who does not have celiac, but whose health improves on a gluten-free diet and worsens again if gluten is eaten. It could even be more than one illness.

“We have absolutely no clue at this point,” said Dr. Stefano, medical director of the University of Chicago’s Celiac Disease Center.

Someone you know may be gluten-sensitive. Although they do not have celiac, they adopt a gluten-free diet and they lose weight and their allergies improve. At the same time they make an effort to eat more fruits,vegetables and nuts.

Many advocates of gluten-free diets warn that non-celiac gluten sensitivity is a wide, unseen epidemic undermining the health of millions of people. They believe that avoiding gluten — a composite of starch and proteins found in certain grassy grains like wheat, barley and rye — gives them added energy and alleviates chronic ills. Oats, while gluten-free, are also avoided, because they are often contaminated with gluten-containing grains.

Others see the popularity of gluten-free foods as just the latest fad, destined to fade like the Atkins diet and avoidance of carbohydrates a decade ago.

Indeed, Americans are buying billions of dollars of food labeled gluten-free each year. And celebrities like Miley Cyrus, the actress and singer, have urged fans to give up gluten. “The change in your skin, physical and mental health is amazing!” she posted on Twitter in April.

For celiac experts, the anti-gluten zeal is a dramatic turnaround; not many years ago, they were struggling to raise awareness among doctors that bread and pasta can make some people very sick. Now they are voicing caution, tamping down the wilder claims about gluten-free diets.

The experts agree that some people who do not have celiac receive a genuine health boost from a gluten-free diet. They just cannot say how many.

As with most nutrition controversies, most everyone agrees on the underlying facts. Wheat entered the human diet only about 5,000 years ago, with the advent of agriculture.

The primary proteins in wheat gluten are glutenin and gliadin, and gliadin contains repeating patterns of amino acids that the human digestive system cannot break down. (Gluten is the only substance that contains these proteins.) People with celiac have one or two genetic mutations that somehow, when pieces of gliadin course through the gut, cause the immune system to attack the walls of the intestine in a case of mistaken identity. That, in turn, causes fingerlike structures called villi that absorb nutrients on the inside of the intestines to atrophy, and the intestines can become leaky, wreaking havoc. Symptoms, which vary widely among people with the disease, can include vomiting,chronic diarrhea or constipation and diminished growth rates in children

The vast majority of people who have celiac do not know it. And not everyone who has the genetic mutations develops celiac.

What worries doctors is that the problem seems to be growing. After testing blood samples from a century ago, researchers discovered that the rate of celiac appears to be increasing. Why is another mystery. Some blame the wheat, as some varieties now grown contain higher levels of gluten, because gluten helps provide the springy inside and crusty outside desirable in bread. (Blame the artisanal bakers.)

There are also people who are allergic to wheat (not necessarily gluten), but until recently, most experts had thought that celiac and wheat allergy were the only problems caused by eating the grain.

For 99 out of 100 people who don’t have celiac — and those who don’t have a wheat allergy — the undigested gliadin fragments usually pass harmlessly through the gut, and the possible benefits of a gluten-free diet are nebulous, perhaps nonexistent for most. But not all.

Anecdotally, some people say that gluten-free diets have improved their health. Some people with diseases like irritable bowel syndrome and arthritis also report alleviation of their symptoms, and others are grasping at gluten as a source of a host of other conditions, though there is no scientific evidence to back most of the claims. Experts have been skeptical. It does not make obvious sense, for example, that someone would lose weight on a gluten-free diet. In fact, the opposite often happens for celiac patients as their malfunctioning intestines recover.

They also worried that people could end up eating less healthfully. A gluten-free muffin generally contains less fiber than a wheat-based one and still offers the same nutritional dangers — fat and sugar. Gluten-free foods are also less likely to be fortified with vitamins.

But those views have changed. Crucial in the evolving understanding of gluten were the findings published in 2011, in The American Journal of Gastroenterology, of an experiment in Australia. In the double-blind study, people who suffered from irritable bowel syndrome, did not have celiac and were on a gluten-free diet were given bread and muffins to eat for up to six weeks. Some of them were given gluten-free baked goods; the others got muffins and bread with gluten. Thirty-four patients completed the study. Those who ate gluten reported they felt significantly worse.

That influenced many experts to acknowledge that the disease was not just in the heads of patients. “It’s not just a placebo effect,” said Dr. Marios Hadjivassiliou, a neurologist and celiac expert at the University of Sheffield in England.

Even though there was now convincing evidence that gluten sensitivity exists, that has not helped to establish what causes gluten sensitivity. The researchers of the Australian experiment noted, “No clues to the mechanism were elucidated.”

What is known is that gluten sensitivity does not correlate with the genetic mutations of celiac, so it appears to be something distinct from celiac.

How widespread gluten sensitivity may be is another point of controversy.