Why We Bother Checking
Anyone can print a badge on a jar. What ISO 22000 tells us is that a third party actually went and checked, not just once, but on an ongoing basis, because certification needs to be maintained and re-audited. For a supplement you're putting into your body regularly, that's a genuinely different level of assurance compared to a brand's own marketing claims.
It also matters because manufacturing is where a lot can quietly go wrong, contamination, incorrect dosing, mislabelled batches, even when the ingredient list itself looks perfectly fine on paper. ISO 22000 is specifically aimed at catching that stuff before it reaches you.
You can read more about how ISO standards work generally on the official ISO 22000 standard page, and the UK's Food Standards Agency covers how food safety is regulated more broadly here.