My impression is that high intake of metals — iron, potassium, sodium, magnesium, selenium — bring some risk. The problems of excess sodium intake — through the "supplement" of eating heavily salted food is well known. I was take a daily potassium supplement because I had the impression that my diet was low in potassium, and I was also keeping sodium intake low. (I mention sodium because perhaps sodium/potassium balance is important.) After some months of taking potassium, I started having brief petit mal seizures, and I learned that potassium can indeed trigger seizures: https://www.sciencedirect.com/science/article/abs/pii/S0920121118300664

While I do take some supplements — B12, vitamin D, calcium, fish oil — I have abandoned most and look for good food sources — for example, 1 brazil nut a day for selenium.

Thanks for the article. Supplements should be treated with caution.