> The UK govt recommends a 100IU supplement [...] current understanding is that an adult needs 1000-2000IU The NHS recommends you consider taking 400IU, and no

> The UK govt recommends a 100IU supplement [...] current understanding is that an adult needs 1000-2000IU The NHS recommends you consider taking 400IU, and not more than 4,000IU: https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-d/ https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-... (That page also says 400IU is what adults need, do you have a source for your 'current understanding' by any chance?