Re: Supplement companies and peoples information
The internet is a pretty busy place.
As said, companies may change name, close down and the owner open a new one and take migrate all the contacts. Very often supplement companies are also part of a group, all being owned by a single, far less known parent company. This also happens with fast food franchises, clothing stores, supermarket chains, etc. And often when this happens any information you give to any company in the group will be shared and accessible by all of them (and this is usually stated in the terms of agreement that nobody bothers to read when they register).
There's also companies that have the single job of picking personal information over the internet. Sometimes we're talking about stealing credit card numbers, but most often it's just getting people's mail addresses, knowing their interests or history for commercial and marketing reasons.
Hell services like google compile information on every user, the things they search for, what they buy, the sites they most often visit, what other services they use etc and cross-reference everything to get an idea of what kind of person each user is and how they could "sell" them something (even in the most abstract sense, when google provides you with a free service they're still making money off you every time you open one of their pages and see a banner from another company that pays google to advertise there).