Here's this particular brand if you live in the prison hulk called Australia. I take it regularly, very acidic but mixed with a decent amount of water it goes down well.I gave some to a friend who has suffered from sinus trouble for decades, her nose runs constantly and antibiotics provided only temporary relief. It cleared in 4 days! She stopped taking it the problem returned in 5 days, resumed it, cleared up and no further problems, takes one gram per day without side effects. She takes it in powdered form and it's a brand that I can't find online but it's available at Priceline Chemists in Australia for less than $20.
I was on an extended fishing trip a couple of weeks ago. Punctured my fingers with dirty hooks, scratched and cut myself clambering over rocks and walking through the spiky Aussie bush. Got splinters too, whereas before these were taking longer to heal on my middle aged body, they all healed very quickly, seems to work.
I also haven't had any colds, flu or the dreaded plague this season, first time in years this has happened, usually get one cold.