Is there any scientific research available on the dietary requirements of gold(if any at all)? The motivation for my question comes from the Edgar Cayce readings(holistic medicine). According to Cayce, several diseases are caused by a lack of gold in the diet or the body's inability to metabolize the gold. As to what foods contain trace elements of gold, that is another topic altogether. As to whether or not you believe in Cayce's supposed psychic abilities is also irrelevant to my question, humor me and assume that there may be some scientific validity to his claim.
There's no established lower or upper intake level, but there's data showing that the average human body contains around 3ppb of gold, mostly in the form of nanoparticles.
Here's a long review of the academic literature on medical uses of gold nanoparticles: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3347577/
In particular, it has a lot of effects on the immune system and it has been used as an adjuvant.