Are cravings your body's way of saying you need some mineral, vitamin, or chemical in that food?

When I was pregnant I craved McDonald’s cheese burgers. Not Burger King or any one else. Only McDonald’s would do. I also craved broccoli, which I had never cared for before then. Since then I love broccoli.

Here lately I’ve been kind of craving tomatoes. I bought a jar of tomato juice and checked the label. Among other things, one serving has 30% of your suggested daily intake of salt…and my sodium levels are a little low, at 131. (I did labs yesterday because this has been an ongoing problem.)
So could that be it, the salt, or could it be something else, like iron?

Or is it all BS and doesn’t mean a thing?