Nutrition research Observational studies make sense?

Uwe Knop: Nutrition Research: Observational studies bring no solutions

03/01/2014

In a recent BMJ publication, US medical professor John Ioannidis, Stanford University, sums up the dilemma of nutrition science: many study results are „completely unbelievable“ - and also one „another million observational studies“ would not provide any definitive solutions [1]. Especially for the hardest end point of study, total mortality, the effects of individual nutrients „equals zero“. The research in this area „appears hopeless“. The BMJ publication thus confirms statements by the German Cochrane Director, Professor Gerd Antes: „The nutritional sciences are in a pitiable situation.“ [2]

In Germany too, in recent years, numerous scientists have pointed to the basic problem that nutritional observation studies do not provide any proof - in addition to Professor Gerd Antes, for example, Dr. med. Klaus Koch, Head of Health Information at the IQWiG, Professor Walter Krämer, Economic and Social Statistics, University of Dortmund, Professor Peter P. Nawroth, Director of Internal Medicine and Clinical Chemistry, Heidelberg University Hospital or Professor Gabriele Meyer, Chair of the German Network on Evidence-based Medicine (DNEbM) [ 2]. „At the German Society for Nutrition DGE, however, these findings still seem unknown - which is clear in the new DGE booklet on fruit and vegetables [3]: The 5-a-day propaganda that vegetarian food promotes and protects the health´, will continue on the basis of observational studies - and although there is no basic evidence of the health benefits of fruit and vegetables, there is no evidence that the 5-a-day campaign promotes citizens' health“, explains nutritionist Uwe Knop. Therefore, no one knows if state vegetable propaganda is related to the rising numbers of clinical cases of gastrointestinal disease documented by federal health reporting since the campaign began [4]..

Doubts about dietary recommendations
Even the DGE did not make it clear until September 2013 that one could not say that fruits and vegetables protect against cancer and cardiovascular diseases - responsible are rather unspecific effects [5].. „Such contradictory statements make people doubt the general credibility of nutritional recommendations, as recently confirmed by a study from the University of Minnesota“ [6], says Knop, „and rightly so, because the 'ecotrophological Universalcredo´ is: you do not know anything specific ... “ (UK)

Sources:
[1] Implausible results in human nutrition research - Definitive solutions won´t come from another million observational papers or small randomized trials, BMJ 2013; 347
[2] „Meat red, human dead“, Frankfurter Allgemeine Sonntagszeitung, 1.4.12, p. 57 / „Food as a cure - False fruits“, SZ sueddeutsche online, 14.4.11 / „Medical studies are often based on unverified assumptions“, Mirror online: 23.7.12 / „Nutrition rules: where are the dates?“ Novo arguments, 03.04.2013
[3] Vegetables and fruits - all-rounders in the field of health protection, DGE flyer, 1st edition 2013
[5] 5-day campaign: It is fermenting, EU.L.E.N mirror, 1-2 / 2013
[5] Food without remorse, Frankfurter Rundschau, 30.09.13
[6] Adverse Outcomes Associated With Media Exposure to Contradictory Nutrition Messages, Journal of Health Communication: International Perspectives, Published online: 11/10/13
Read on topic: „Belief (s) instead of knowledge“ (Nutritional observational studies explained in the style of „Show with the mouse“, out: „Eat what you want“, rowohlt e-book, Oct. 2013, Uwe Knop)
Image: Jörg Brinckheger / pixelio.de