Comments on: “The role of dietary sugars in health: molecular composition or just calories?”

Abstract

We read with interest the narrative review by Prinz [1] on the question whether dietary sugars per se have an unfavorable health effect, or if it is just the amount of calories that matters in the development of non-communicable diseases (NCD) and obesity. As the author is working for the German Sugar Association, his conclusion was to be expected: in his view, the scientific evidence does not support the conclusion that dietary sugars themselves are detrimental, but it is simply the excess amount of calories which is to blame [1]. Besides the fact, that narrative reviews should be in the opinion of these authors only be performed for novel topics for which evidence is just starting to arise, Prinz’ argumentation strategy has some gaps, we would like to bring the readers’ attention to. First, there is evidence from both observational studies and from trials, that the intake of (free) sugars or sugar sweetened beverages (SSB) determines body weight [2–4]. We agree, that in free living individuals this increase in body weight or body fat is mediated by an increase of total energy intake [3]. However, a recent review of 11 trials in the SACN Report on Carbohydrates and Health clearly pointed on an inadequate compensation for energy delivered as sugars [4]. Thus, under ad-libitum circumstances, a high dietary sugar intake promotes high energy intake and thus promotes weight gain. Second, in the type 2 diabetes (T2D) section, Prinz did not clearly separate between total sugar, all dietary sugars, fructose, or sucrose. In addition, he twists the interpretation of the systematic review and meta-analysis of prospective cohort studies on SSB and risk of T2D, and metabolic syndrome [5] who clearly wrote that “in addition to weight gain, higher consumption of SSBs is associated with development of metabolic syndrome and type 2 diabetes.” That a similiar association between SSB and overweight or type 2 diabetes has also been seen for fruit juices [6], as stated by Prinz [1], is not surprising, as sugar and energy contents of these groups of beverages are comparable. However, this does not mean, that SSB are discharged. Instead it emphasizes the definition of free sugars as proposed by the WHO, i.e., the sum of added sugars (incl. sugars from honey, syrup, and fruit juice concentrates) and sugars from juices [7]. Furthermore, the Prinz’ review gives good examples for cherry picking results of scientific studies as a tactical approach to support the own hypothesis. For example, he pointed out that diet rich in fats stimulate secretion of gastrointestinal peptides and appetite scores, much more than a diet rich in sucrose or SSB [1]. However, the citied crossover trial [8] also states, that total energy intake was higher after the energy-containing beverages compared with water, no matter if semi-skimmed milk or SSB were consumed. Obviously, this trial supports the increase of total energy intake by SSB instead of caloric free beverages [8]. Moreover, as in SSB all energy comes from added sugar it is a fake discussion whether energy or sugar content of SSB is responsible for their contribution to the development of overweight and obesity, as done by Prinz [1]. In conclusion, the need to restrict the intake of free sugars to avoid obesity and its comorbidities is well acknowledged [2, 4, 7]. We are surprised, that a respectable scientific Journal as The European Journal of Clinical Nutrition offers the sugar industry a stage to publish a obviously biased report to undermine effective public health policies and programs [9]. The scientific evidence is convincing enough to start action and establish public health measures to limit energy intake from free sugars. * Ute Alexy [email protected]