Disclaimer: I am not endorsing any company listed in the following, nor any supplement mentioned in here. The questions for Huel are in the past paragraph.
I came across this reddit post that contains an interesting video on laboratory setup and methods, and discussing purity of various products in the supplement industry.
The feeling I get from it is that lots of supplement providers don’t use testing from reputable labs, or unintentionally (or perhaps even intentionally) use testing methods that don’t end up properly separating the desired substance from others.
Huel uses many different suppliers for the various micronutrients (vitamins, minerals, lutein, lycopene, …) that need to be topped off in the powder due to not being contained in sufficient quantities in the oats/flax/… Does Huel simply trust the supplier provided certificates on testing, or does Huel send each supplier’s product for independent testing? Does it get tested in a properly certified and accredited laboratory? Has Huel verified that the laboratory is using the correct methods for testing (such as the difference between liquid chromatography vs UV spectroscopy as discussed in the reddit post)? Would Huel be willing to regularly share these lab results (possibly censoring the supplier name to protect Huel secrets)?