4.5. Limitation and Strength
IBS, sucrase-isomaltase deficiency
SUCRASE-ISOMALTASE DEFICIENCY
This trial has several limitations. The intervention periods were of relatively short duration, and the effects on the microbiota and metabolites could have been more pronounced with longer durations. However, the intervention periods were decided on to enhance participation for the primary endpoint of investigating IBS symptoms and the microbiota investigation was exploratory. Regardless, the effect after one week of intervention are still of high interest. Similarly, the one-week washouts might not have been sufficient to eliminate carry-over. However, analysis of the sequence order did not show any indications of systematic differences. We therefore assume that one week of washout was sufficient. Furthermore, a hydrogen breath test was not used, which would have given a direct measure of fermentation. The use of sucrose as a placebo can be questioned, due to reported sucrase-isomaltase deficiency in IBS [A particular strength of this study was the double-blind study design, which reduced the risk of bias, combined with a large sample size and a three-way placebo-controlled cross-over design, which should limit the contribution of individual variability to treatment effects. Another strength is the elimination-exposure character of the study, making the molecular responses specific to the exposures, not confounded by the treatment effect. Furthermore, the joint analysis of gut microbiota and metabolites added knowledge about the physiological effect of FODMAP intake, both regarding gut microbiota composition and functionality, which may be of relevance to health, although more research is needed.