Like other ktard said, they being around for decades. I remember back in school guardian was already selling them.

But you are not the only 1, even my mother & aunt also wary cause the price is cheaper.

To be fair, unless you have a very serious vitamin deficiency & need exact dosage every day. There's no harm in trying 21st century or house brand to save money. Read the labels content to see if the vitamin content is sufficient.