L dopa content in supplements

[realk]

This article says that the supplement labels show different l dopa content than the values measured... Some less, but what is strange, many of them more...Does anyone know the brand you can rely, ideally regularly tested by independent lab and published results?

newatlas.com/health-wellbei...

[Boscoejean]

this article suggests that these supplements are tested but is it credible?

candystore.com/blogs/guides....

[Buckholt]

By definition, anyone taking supplements is concerned for their health and the competition is fierce between suppliers. Companies spend a fortune on marketing, packaging and endorsements but that’s not really what people want. If a company had each batch of its products tested by a third party and published the results, I think it would generate many sales and build trust and loyalty.