There's a popular theory (hormesis I think it's called) that says this. It's also just something that's popular among people that are "just logically thinking"

There's a popular theory (hormesis I think it's called) that says this. It's also just something that's popular among people that are "just logically thinking" / "using common sense", I've heard it for as long as I've had glasses (decades). Not a single doctor has agreed with this sentiment and I've never found any significant studies conducted that support this claim. If it were true you would expect it to have a lot more actual backing than it does, especially given how long the theory has been around now.