@WouldIBeATwat
It does happen pretty quickly. A lot of people are magnesium deficient. Transdermal absorption is fast.
@CinnamonJellyBeans
One of the main causes of IBS-D is microbiome imbalance in the aftermath of food poisoning. Basically the body continues to attack itself with the same defences it has used against the bacteria in the food poisoning. With repeated instances of food poisoning this can progress to being an autoimmune condition.
The main bacterial culprit behind IBS-D in this situation is sulphate reducing bacteria, which are healthy and actually promote a longer life span when the microbiome is in balance. However when they become too prolific this is very bad for the body as SRBs turn dietary sulphur in hydrogen sulphide (smelly gas) and sulphuric acid (causes burning, cramps, diarrhoea, bleeding etc).
This is especially difficult for people who naturally h e a high level of SRBs because they have issues with the processing of sulphur in the body anyway. This is largely genetic.
A way to help regulate this is to provide the body with sufficient levels of sulphate via a transdermal rather than a digestive route so the body doesn’t really on the sulphur content in foods, as having a diet high in sulphur is literally pouring fuel in the INS flames in these cases.
If you want more information about hydrogen sulphide and it’s role in IBS I recommend the research of Dr Mark Pimentel of Cedars-Sinai. His body of work is pretty recent, mostly in the last decade or so.