My mother told me all about scurvy when I was five and trying to resist eating pumpkin and let me tell you it’s been 35 years and I still get nervous if I go for two days without eating a green vegetable.
I told my own little picky eater about scurvy, rickets etc and now one of her most frequently requested lunch items is baby spinach, closely followed by carrots.
I’m not saying everyone should mildly traumatize their children to make them understand that vegetables are vital to ongoing possession of your teeth and organs, but.. no, that’s exactly what I’m saying. Go for it.