The amount of potassium or sodium cyanide needed to kill an adult is around 200mg. This is like 10 grains of salt. You would die of dehydration if you only had 200mg of water every day too.

The hooey about homeopathic doses and vaccination are two examples of medical fraud. That still go on, unprosecuted. Very few things that are toxic in relatively small amounts are in any way helpful in any amount.

Fluoride is a good example. In small doses it is not toxic, but it slowly displaces iodine in the thyroid until the gland cannot produce adequate amounts of Thyroxin and other hormones. The rate of elimination of fluoride is a lot slower than several days because it sockets into every place where chloride and iodide would normally go, this is because it's smaller and electrostatically similar.