A very dear long time friend of mine suddenly passed away at age 67 a little over two years ago while taking an afternoon nap. It was quite a shock as she was very active and apparently physically and mentally healthy. An autopsy was conducted to determine the cause of death. She had suffered no heart attack or stroke; it was quite mysterious. Many samples were taken and sent away for laboratory analysis. It turned out she had so much potassium in her blood it had stopped her heart. She was keen on supplements and thought she had enough medical knowledge to self prescribe as she had been a veterinarian's assistant at one time. That was a deadly misjudgment.
I knew that potassium has been used in lethal injections to stop a subject's heart but I was shocked that potassium taken orally as a supplement could stop a heart. My physician confirmed this fact to me.
Medicowesome: Why does heart stop in diastole when plasma potassium level rises?
As I lived in Los Alamos, NM at the time I knew or knew of some of the women taking significant amounts of L-tryptophan who suffered the repercussions enumerated in the following links. My former wife had been involved with them and was pushing me to take numerous supplements which I refused to do. The lead woman was a nurse. As a pharmaceutical grade was apparently not approved or unavailable in the USA, she was buying it in large tins from Japan of a purity level used for administration to animals, but not humans. The women were manually loading it into capsules to be taken orally. The results were disastrous. These self prescribing women all thought they knew more than their physicians about supplements.
https://pdfs.semanticscholar.org/b54...76d4f0b274.pdf
THE DOCTOR'''S WORLD; How Medical Detectives Identified The Culprit Behind a Rare Disorder - The New York Times
Evidence Links Japanese Firm to Epidemic in 1989 : Research: A potentially fatal blood and muscle ailment has been tied to impurities in the manufacturer'''s supply of the dietary supplement L-tryptophan. - Los Angeles Times