Which lab test you use as your starter marker is up to you. They are all accurate. We know some Facebook groups and some RDs only use Monash and caution folks away from FODMAP Friendly. I have never heard one convincing argument as to why. If you read the articles linked above, you can certainly draw your own conclusions.   To those who say it makes things more confusing, here is my take: your patients, or you yourself, will find conflicting information online and elsewhere. If you do not know the sources of the differences of opinion, or how they came to those conclusions, you truly cannot make a judgement or a decision.    Once you do know that all the labs used are reputable, that lab results will vary regardless due to variety of produce, ripeness, handling, storage and country of origin, then you begin to understand that all these results are just what were detected in a snapshot in time.