背景:近年来已发表了许多关于低热量甜味剂(LCS)的系统综述(SR)和荟萃分析(MA),得出LCS有益的结论,中性,或对各种健康结果的有害影响,取决于审查。
目的:本综述的目的是确定SR调查LCS消耗与体重(BW)之间的关联的方法如何影响他们的发现,以及MA结果是否可以提供一致的估计效果。
方法:PubMed的系统搜索,Scopus,和CochraneLibrary于2022年11月进行了研究,以确定研究LCS消耗与BW之间关联的随机对照试验(RCT)或非随机研究(NRS)的SR。方法,MA结果,并从每个合格的SR中提取结论。
结果:在985个搜索结果中,20SR评估了LCS和BW之间的关联,来自75RCT的出版物,42项前瞻性队列研究,和10项横断面研究。每个SR属性中包含的研究相当缺乏重叠,在某种程度上,纳入基于设计的研究;因此,每个SR合成的结果来自截然不同的研究。证据合成方法是异质的,通常是不透明的,这使得很难确定为什么某些研究的结果被排除在外,或者为什么在SR之间观察到不同的结果。
结论:SR调查LCS对BW的影响采用不同的方法来回答据称相同的问题,从一组不同的异质性研究中提取,忽略MA所需的基本假设,导致不同的结果和结论。以前的MA显示了研究设计的巨大影响,这导致RCT的MA和NRS之间LCS对BW的影响的估计不一致。鉴于长期RCT的可用性,这些研究应该是确定LCS和BW之间因果关系(或缺乏因果关系)的基础.该试验在PROSPERO注册为CRD42022351200。
BACKGROUND: Numerous systematic reviews (SR) and meta-analyses (MA) on low calorie sweeteners (LCS) have been published in recent years, concluding that LCS have beneficial, neutral, or detrimental effects on various health outcomes, depending on the review.
OBJECTIVE: The objective of this overview of reviews was to determine how the methodologies of SR investigating the association between LCS consumption and body weight (BW) influence their findings and whether MA results can provide a consistent estimated effect.
METHODS: Systematic searches of PubMed, Scopus, and Cochrane Library were conducted in November 2022 to identify SR of randomized controlled trials (RCT) or non-randomized studies (NRS) investigating the association between LCS consumption and BW. The methods, MA results, and conclusions were extracted from each eligible SR.
RESULTS: Of the 985 search results, 20 SR evaluated the association between LCS and BW, drawing from publications of 75 RCT, 42 prospective cohort studies, and 10 cross-sectional studies. There was a considerable lack of overlap of studies included within each SR attributed, in part, to the inclusion of studies based on design; thus, each SR synthesized results from distinctly different studies. Evidence synthesis methods were heterogeneous and often opaque, making it difficult to determine why results from certain studies were excluded or why disparate results were observed between SR.
CONCLUSIONS: SR investigating the effect of LCS on BW implement different methodologies to answer allegedly the same question, drawing from a different set of heterogeneous studies, ignoring the basic assumptions required for MA, resulting in disparate results and conclusions. Previous MA show the large effects of study design, which results in inconsistent estimates of the effect of LCS on BW between MA of RCT and NRS. Given the availability of long-term RCT, these studies should be the basis of determining causal relationships (or lack thereof) between LCS and BW. This trial was registered at PROSPERO as CRD42022351200.