Gluten Sensitivity: Real Thing Or Nocebo?

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1435497_42016849Gluten, a complex protein derived from wheat, rye and barley, probably heads the list of popular foodstuffs to avoid this decade. Websites and twitter feeds abound with avowals of how much better their lives are without it from weight loss to energy levels, avoiding gluten has been a huge benefit.

Is it a smart food choice? Or is it just another fad like many weight loss miracle pills, powders and martini diets?

First, let's be clear that gluten can be destructive for some people those with celiac disease (CD), which affects about 1 percent of the American population. Celiac disease is an autoimmune condition in which anti-gluten antibodies attack the cells lining the intestinal tract, leading to serious deficits in nutrient absorption as well as GI cramps, constipation and/or diarrhea. Children who manifest the condition will also suffer from stunted growth since they won't be able to get sufficient nutrients for normal developed.

Celiac disease can be diagnosed by blood tests for antibodies as well as by intestinal biopsies that examine the status of the intestinal lining but reported "gluten sensitivity" is another issue altogether. Many people who do not have these antibodies or whose intestinal lining doesn't indicate such damage still say that gluten has negative effects on them, causing cramps and other symptoms when they consume gluten-containing foods such as cereals, breads or pasta. Because of the popularity of going gluten-free, a clinical diagnosis of non-celiac gluten sensitivity, or NCGS, was created. But most doctors have questioned whether this diagnosis refers to a real entity, or if it is just another example of the "nocebo effect," the opposite of the placebo effect. Unlike a placebo, where a fake pill makes someone feel better, a nocebo makes people feel better when they stop taking it, even though there is no effect.

To distinguish between these possibilities, Dr. B. Zanini of the University and Spedali Civili of Brescia, Italy reported the ability of people who said they had NCGS to detect the presence of the protein in their food. The experiment involved 35 people (31 women) who had been on gluten-free diets for 6 months. None had celiac disease, as determined by blood tests.

The participants were randomly assigned to receive small packets of flour that either did (packet A) or did not (packet B) contain gluten. They added the flour to their foods for ten days, after which they ate their regular diets without adding anything for 2 weeks. Then, they again were given the packets of flour in the reverse order, that is getting packet B if they used A the first time. Again, they were instructed to add the flour to their food for another 10 day period.

At the end of each diet period, participants were asked if they had been given flour with or without gluten. Only 12 (34 percent) of them were able to correctly identify the gluten-containing flour. In addition, these people also had significantly higher scores on symptom-related questions when they had been eating gluten.

Conversely, 17 people who ate the gluten-free flour thought they had indeed consumed gluten, and their reports of symptoms were greater after that flour than after the gluten one. And six people were unable to distinguish between the flours.

The authors said "our study has shown that gluten challenge leads to a recurrence of symptoms in only a third of patients fulfilling the recognised diagnostic criteria for the clinical diagnosis of NCGS. Consequently, NCGS is likely to be the correct diagnosis in only a minority of those who do not have CD, but whom themselves choose to follow a GFD [gluten-free diet]. "

This study and others like it support the validity of a NCGS diagnosis in some people. But it is also likely that for many avoidance of gluten is just following the latest fad. The danger here lies in the fact that some foods that tout the freedom from gluten are actually less healthful than the original variety because they may contain more fat or sugar and thus more calories. The bottom line is that if you don't really need to go gluten-free, don't bother. And to determine if you do, consult a gastroenterologist, not a celebrity diet guru.