Gluten and MC

[wmonique2]

Tex,

Have you seen this? Puzzling.



https://www.healio.com/gastroenterology ... ac-disease


Love,

Monique

[tex]

Hi Monique,

That's an interesting article. After reading it, I have to question the validity of their so-called "research". Here's how they obtained their data:

They estimated gluten intake using food frequency questionnaires taken every 4 years and confirmed microscopic colitis after reviewing medical records.

"Estimated"? — using food frequency questionnaires taken every 4 years? That's about as un-rigorous as medical research can get.

I must have misread and misinterpreted the article because that doesn't make much sense.

Thanks for posting. That is indeed puzzling.

Love,

Tex

[Rosie]

I took a look at the article. I have to agree with you, Tex, that it isn't a very well-designed study. What they did was compare the various amounts of gluten eaten and they found that those eating a lesser amount of gluten had the same risk of developing MC as those eating a lot more. They didn't appear to have compared those on a completely gluten-free diet with those eating any amount of gluten. And we know that if you are sensitive to gluten, a little is just as bad as a lot. Also, if someone is on a gluten-free diet, their chances of developing MC are probably much less than the gluten-eating population. They would be concealed in the vast number of people who didn't develop MC. So their research is pretty much worthless........

Rosie

[Kilt]

I have to question the validity of their so-called "research". Here's how they obtained their data:

They estimated gluten intake using food frequency questionnaires taken every 4 years and confirmed microscopic colitis after reviewing medical records.

"Estimated"? — using food frequency questionnaires taken every 4 years? That's about as un-rigorous as medical research can get.

The validity of gluten energy intake estimates would depend on the detail of the questionnaires and the method used to analyze the responses.

I can't open up the OP's linked study to see the methodology because it's behind a pay wall. However, the abstract says the data were taken from the Nurses Health Study (NHS) and the NHSII. In searching on the NHS, I found the following study, which doesn't involve microscopic colitis but which does describe in methodological detail how gluten energy intake is estimated from the NHS diet questionaires:

Long term gluten consumption in adults without celiac disease and risk of coronary heart disease: prospective cohort study

In 1986, diet in both cohorts was assessed with a validated 136 item semiquantitative food frequency questionnaire.

Energy adjusted gluten intake was estimated as follows:

In both cohorts, diet was assessed in 1986, 1990, 1994, 1998, 2002, 2006, and 2010. For each food item, participants were asked about the frequency with which they consumed a commonly used portion size for each food over the previous year; available responses ranged from never or less than once a month to six or more times a day. We calculated nutrients by using the Harvard T. H. Chan School of Public Health nutrient database, which was updated every two to four years during the period of food frequency questionnaire distribution.19 We used year specific nutrient tables for ingredient level foods. Previous validation studies have shown that the derivation of nutrient values correlates highly with nutrient intake as measured by one week food diaries in women and men.2021

For each of these two cohorts, we derived the quantity of gluten consumed. We calculated the quantity of gluten on the basis of the protein content of wheat, rye, and barley based on recipe ingredient lists from product labels provided by manufacturers or cookbooks in the case of home prepared items. Previous studies have used conversion factors of 75% or 80% when calculating the proportion of protein content that comprises gluten; we used the more conservative estimate of 75%.222324 Although gluten’s proportion of total protein may be more variable for rye and barley than for wheat,25 we used the same conversion factor for all three grains, consistent with previous studies.2223 Although trace amounts of gluten can be present in oats and in condiments (for example, soy sauce), we did not calculate gluten on the basis of these items as the quantity of gluten is much lower than that in cereals and grains and the contribution to total gluten intake would be negligible.26

In 1986 the five largest contributors to gluten in both cohorts were dark bread, pasta, cold cereal, white bread, and pizza (supplementary table A). Previous validation studies within these cohorts found that the Pearson correlation coefficients between the number of servings of these items reported on food frequency questionnaires and that reported on seven day dietary records ranged from 0.35 (pasta) to 0.79 (cold cereal) for women and from 0.37 (dark bread) to 0.86 (cold cereal) for men.2728 A separate validation study of this food frequency questionnaire found that this method of measuring vegetable (that is, plant based) protein intake, of which gluten is the major contributor, correlated highly with that measured in seven day dietary records (Spearman correlation coefficient 0.66).29

We divided cohort participants into fifths of estimated gluten consumption, according to energy adjusted grams of gluten per day. We obtained energy adjusted values by regression using the residual method, as described previously.30 To quantify long term dietary habits, we used cumulative averages through the questionnaires preceding the diagnosis of coronary heart disease, death, or the end of follow-up.31 For example, we calculated cumulative average estimated gluten intake in 1994 by averaging the daily consumption of gluten reported in 1986, 1990, and 1994. We treated cumulative average estimated gluten intake as a time varying covariate. For participants with missing dietary data, we used the most recent previous dietary response on record. Because the development of a significant illness may cause a major change in dietary habits, and so as to reduce the possibility of reverse causality, we suspended updating dietary response data for participants who developed diabetes, cardiovascular disease (including stroke, angioplasty, or coronary artery bypass graft surgery), or cancer. For such patients, the cumulative average dietary gluten value before the development of this diagnosis was carried forward until the end of follow-up.32

Further searching turned up an actual NHSII diet questionnaire for high school ages. It is quite detailed and asks about dietary intakes over a multi-year period.

The NHS, NHSII and NHS3 are conducted by clinicians, epidemiologists and statisticians at the Harvard Medical School, Harvard School of Public Health, Brigham and Women's Hospital, and other related medical institutions. I think these guys are about as rigorous as it gets.

I assume the recent MC/gluten study linked in the OP used a gluten intake estimation methodology similar to the study that I quoted above, which seems quite sophisticated. It's too bad we can't read the discussion and conclusions of the entire study. They could shed further light on the study's relevance to gluten free diets as a treatment for MC as opposed to whether gluten intake is a correlate of non-celiac MC, which seem to me to be slightly different matters.

[tex]

Rosie,

Thanks for confirming that. I was afraid that I was somehow misreading the article. My initial impression was that they don't understand MC, so they didn't realize that the GF diet has to be an all or nothing proposition (as you pointed out), and that's why they designed a worthless study. But that's a dumb assumption. I didn't realize that medical researchers could get away with such sloppy methods.

Tex

[carolm]

I’m unclear how the researcher reached their conclusion that going gluten free AFTER the onset of MC would not be helpful, if gluten wasn’t the reason for the onset of MC. That seems very concrete and over simplistic and completely ignores all of the other factors that prompt the onset of an autoimmune disease.

Just a very short-sighted, poorly conceived study.

Carol

[JFR]

This kind of so-called research is not science but propaganda. Richard Feinman, a biochemist and metabolism researcher, calls nutritional science a oxymoron since most of it is based on epidemiological studies which can't determine causation and faulty data gather like food questionaires that are notorious unreliable.

Jean

[tex]

Hi Kilt,

Sorry, I didn't notice your response before I responded to Rosie last night, but in my opinion, these comments by Carol and Jean say it all:

I’m unclear how the researcher reached their conclusion that going gluten free AFTER the onset of MC would not be helpful, if gluten wasn’t the reason for the onset of MC. That seems very concrete and over simplistic and completely ignores all of the other factors that prompt the onset of an autoimmune disease.

This kind of so-called research is not science but propaganda. Richard Feinman, a biochemist and metabolism researcher, calls nutritional science a oxymoron since most of it is based on epidemiological studies which can't determine causation and faulty data gather like food questionaires that are notorious unreliable.

Amen. I wouldn't give two bits for all the questionaires in the world. I've responded to plenty of questionaires myself, and afterward I've almost always wished that I had been able to be more accurate, but alas, my memory is only human and far from perfect.

If those guys want to do some research, why in the world don't they get off their butts and get away from their computers and at least attempt to do some "real" research, rather than wasting their time reanalyzing old data that has already been analyzed and reanalyzed to death. Of course that's just my opinion, and I could be wrong.

By the way, since that post appears to be your first, welcome to the group.

Tex