Here the abstract of the article:
- INSERM, UMRS, Centre for Research in Epidemiology and Population Health, Institut Gustave Roussy, Université Paris Sud, Villejuif, France.
Diet composition has long been suspected to contribute to inflammatory bowel disease (IBD), but has not been thoroughly assessed, and has been assessed only in retrospective studies that are prone to recall bias. The aim of the present study was to evaluate the role of dietary macronutrients in the etiology of IBD in a large prospective cohort.
The Etude Épidémiologique des femmes de la Mutuelle Générale de l’Education Nationale cohort consists of women living in France, aged 40-65 years, and free of major diseases at inclusion. A self-administered questionnaire was used to record dietary habits at baseline. Questionnaires on disease occurrence and lifestyle factors were completed every 24 months. IBDs were assessed in each questionnaire until June 2005, and subsequently validated using clinical and pathological criteria. We estimated the association between nutrients or foods and IBD using Cox proportional hazards models adjusted for energy intake.
Among 67,581 participants (705,445 person-years, mean follow-up since completion of the baseline dietary questionnaire 10.4 years), we validated 77 incident IBD cases. High total protein intake, specifically animal protein, was associated with a significantly increased risk of IBD, (hazards ratio for the third vs. first tertile and 95% confidence interval being 3.31 and 1.41-7.77 (P trend=0.007), and 3.03 and 1.45-6.34 (P trend=0.005) for total and animal protein, respectively). Among sources of animal protein, high consumption of meat or fish but not of eggs or dairy products was associated with IBD risk.
High protein intake is associated with an increased risk of incident IBD in French middle-aged women.
- PMID: 20461067 DOI: 10.1038/ajg.2010.192
- [Indexed for MEDLINE]
Re this article:
1.Has meat and fish consumption increased dramatically in the last 50 or so years among this cohort of middle aged French women? Not likely, and so while ingestion of more protein than they can digest may be a factor in development of IBD, then how could this be the underlying problem?
2a. How well are the members of this cohort digesting the protein in meat, given the widespread consumption of antacids (including H2 blockers and acid blockers), and the lack of consumption of raw foods (containing enzymes), whole foods, and digestive enzyme supplements? What role does overall under-nutrition play? Also, if undigested protein is a problem, what are the putrefactive bacteria in the bowel doing to undigested proteins? Could bacterial overgrowth of the small bowel -a side effect of acid blockers- be producing a lot of the hydrogen sulfide from sulfur amino acids?
2b. The dairy and egg protein comment is interesting re: digestibility. Meat contains connective tissue, which must be digested away to continue the digestion of the remaining protein in meat, and which itself is tougher to digest than other proteins. While rich in protein, eggs and dairy do not have connective tissue. Undigested meat stimulates the growth of putrefactive (protein-digesting) bacteria, (competitors of beneficial bacteria), and the putrefactive bacteria produce obnoxious compounds like hydrogen sulfide from these amino acids.
3. If the odds ratios are essentially the same for meat protein consumption and total protein consumption, is not the observed correlation related to total protein consumption (and likely under-digestion of protein), and not meat consumption per se? Notice that they reveal their bias, how they use meat consumption as a popular whipping boy in the abstract (essentially throwing red meat at their vegetarian colleagues) and then backtrack to the more relevant “total protein” in their conclusion.
4. In his book, Textbook of Medical Physiology, Guyton notes that the human digestive tract can absorb up to 700 grams of protein per day. But that is only if we eat all day and successfully digest all that protein. To do the latter, we must not interfere with the operations of nature by interfering with digestion; rather, we must assist nature in the digestive phase.
5. The number of IBC cases is so small in this study, just 77, they could all be eating more protein than they can digest – in essence, interfering with their digestion of protein by various means, including taking antacids, H2 blockers, or acid blockers, not eating enough raw foods containing enzymes, not taking digestive enzyme supplements, and under-nourishing their bodies with copious quantities of processed foods, making them less able to cope with the folly of under-digesting proteins.
6. If this result is general, it would be reproduced in other studies, including studies done on other populations (compare Bradford Hill’s criteria) and with similar diseases. It has not been. See:
Clin Nutr. 2017 Oct;36(5):1259-1265. doi: 10.1016/j.clnu.2016.10.009. Epub 2016 Oct 15.
Nutrients. 2017 May 15;9(5). pii: E500. doi: 10.3390/nu9050500.
Both reviews estimate the intake of macronutrients, when what is more relevant – and much harder to measure – is the digestion and absorption of macronutrients, which will only roughly correlate to total intake, a value no one knows with any certainty because people are notoriously bad at quantitative tasks like estimating how much of any particular food they consume each day and computing weekly/monthly averages.
Both reviews are on Crohn’s, one of the two most common forms of the IBDs. If high protein intake drove IBD, we would see an association in Crohn’s, and it would likely be a stronger correlation, the more severe the form of the IBD. They do not.
This irreproducibility in biological correlations is so typical, it is a rule. Guess which study/studies those with a bias against meat consumption cite?
7. Finally, notice the dietary questionnaire. Talk about recall bias! Talk about guaranteed inaccuracy! Not to mention that some people will simply put what they think they should be doing! People are reasonably good at qualitative tasks and poor at best at quantitative tasks. A person who eats very little meat relative to the average may think himself a major consumer and vice versa.