[jerf]

GP may have had a "heart on the edge"; just because your heart is currently beating correctly doesn't mean that it may not be just a wee bit of disruption away from beating incorrectly. Or you could have a lot of safety margin. I don't know whether medical tests could distinguish the two but just in day-to-day life there's very little way for you to tell the difference. (I wish I could; it would help me a lot.)

It is completely possible for "more of a good thing" to have a negative impact on you because it pushes something out of balance beyond what homeostatis can maintain. In principle the best solution is to go get more of what you need to balance it, but that can be easier said than done. Between the things that science still just plain doesn't know and the chaff of all kinds of garbage information about nutrition on the internet it can be very hard to figure out what you need.