Low FODMAP Diet in FD (PDS)

The goal of this dietary intervention study is to assess the efficacy and mechanisms of a low-FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides and polyols) diet in functional dyspepsia patients. The main questions it aims to answer are: * If a low-FODMAP diet can reduce dyspeptic complaints * How a low-FODMAP diet can reduce dyspeptic complaints in functional dyspepsia (FD). Participants will follow a 6-week during low-FODMAP diet followed by powder reintroduction of 6 FODMAPs and 1 control substance.