Vitamin K will counter the effects of some anticoagulants, and can be used as a antidote to overdoses of things like Coumadin. But foods that have a lot of K , like kale, will prevent it from doing what it is supposed to do in people taking it.
Hydrangeas are natural pH indicators as well, showing the pH of the soil the grow in with the color of their flowers. This can result in hilarity, when someone purchases one color of hydrangea then comes back and complains to the store when they change color after being planted in their yard. They do sell soil additives to change the pH of the soil, and thus the color of the flowers, but there’s a limit as to what’s practical. If you’re soil is mostly acidic or basic trying to change one little spot in the flowerbed is going to require constant reapplication as rain and snowmelt diluted the additive over time. Also hilarity from, say, a member of the household dumping pop or lemonade or something in a pot on the porch containing a pink hydrangea and thus turning it blue (or sometimes killing it).
Yeah, I knew that about hydrangeas specifically because I’ve seen those soil add-ins if you need them to change color. As I understand it, making soil more basic is fairly straightforward, but making it acidic is a bit trickier if you have a soil with a pH higher than 7.5. My soil is around that pH (according to the soil tests I’ve had done this year), but the acidifier I used seemed to have worked well enough, as the plants grew as well as they did at the old house (which had a more neutral to slightly acidic soil pH.)