There is some suggestion that she was on a high fruit diet which may have raised potassium which could cause heart problems under an intensive exercise regime. But suicide is much more newsworthy, isn't it, especially with her hinterland. She always seemed like a bright young woman to me.
If this is the case then it sounds as though her diet wasn't being supervised. Unfortunately many people put themselves on strict diets without seeking medical advice first, which they really should do because of imbalances the diet could cause in their bodies. We're like finely-tuned instruments where even a slight change could be enough to upset the body's chemistry, sometimes with unpleasant results.
Of course suicide makes for sensational media headlines because, sadly, that sort of thing sells newspapers, but unfortunately being bright and intelligent, or even having a young family to consider, doesn't stop people from becoming so depressed they just want to end it all. In fact psychiatric research shows that the more intelligent the person the more likely they are to fall victim to mental health problems. It's equally possible though that, if she did indeed take an overdose, then it was an accidental one.