An even better option is to go to your GP and have them run your bloodwork. It's...

		Etheryte 34 days ago \| parent \| context \| favorite \| on: Vitamin D reduces incidence and duration of colds ... An even better option is to go to your GP and have them run your bloodwork. It's cheap, depending on where you're from it might even be free, and you don't have to guess or randomly pick supplements you read about online. Most people on HN will live to a very high age, there's no reason to take random gambles on what you do to your body.

For sure, you're essentially flying blind without bloodwork. I get a full panel at least 3x/year.