Yes - they are from the USA so some aspects need to be interpreted. We have to be careful about exact equivalents in food, weights and measures, etc. And no fact sheets - anywhere - cover everything.
But these factsheets are in my view among the best single sheet informations sources about numerous things that could be regarded as dietary supplements. If you want to go further, they have references. If you want a simpler, shorter option, their Consumer sheets provide that.
Far, far better for the purpose than the UK information such as Food Standards Agency and NHS websites. (Not being exact equivalents, I might be somewhat unfair here.)
There is a section on National Institutes of Health in my links document which has links to many of them. It was fairly complete and working when I created the document but time does tend to take its toll on websites.
helvella's Links and References document contains many links to other organisations
A single document containing numerous links to relevant websites. With a focus on the UK it nonetheless includes many non-UK sites.
Rather than a simple list of links, there is a page (or more) per site. This is intended to provide some flavour of the site before you decide whether to visit.
Content on HealthUnlocked does not replace the relationship between you and doctors or other healthcare professionals nor the advice you receive from them.
Never delay seeking advice or dialling emergency services because of something that you have read on HealthUnlocked.
Advice on my array of recommended supplements (per endocrinologist”s recommendations)
Vitamin supplements
No more T3 on prescription? 
