Is this about concentrated synthetic vitamin C or about the natural form? From a chemistry perspective the same, but the natural one comes in a different "package" of other substances (vitamin C complex). I wonder if the effect is the same.
Shameless plug: https://www.beehome.design/ I worked on an app that lets you design your own Bee Home and let it be fabricated at a local makerspace. This way you can help the population of solitary bees.
It actually isn’t. 400 IU is based on preventing disease. To obtain optimal health though, dosages should usually be much higher. Obviously this differs from person to person, but 2000 IU should lead to optimal vitamin D levels. This is an interesting video on the topic: https://www.youtube.com/watch?v=jeLC_b5gDUM
I asked a similar question some time ago: https://news.ycombinator.com/item?id=13284742 not about the experience, but more about what to keep in mind when switching. Hope it helps.
> Every day, in doctors’ offices across the US—as well as in Canada, the UK, Ireland, Amsterdam, Australia, Sweden, in 80 countries and on every continent
Amsterdam is not a country. The country is called The Netherlands. Amsterdam is the capital.