I've been looking for help topics about methanol in metabolism. Specifically, I wish to know what is a common dietary component that generates methanol following metabolism and comment on its toxicity? I cannot seem to find any relevant data and i'm seeking to know if anyone here has any experience and knowledge of this.
This is an old question by now, but I found it interesting, so here's my two cents :)
Methanol has long been known to normally occur in humans; one study from 1963 demonstrates its presence in breath.
One major source for methanol in humans is breakdown of pectin by bacteria in the gut. Pectin is a complex carbohydrate found in many fruits and other non-woody parts of plants. Pectin is not well metabolized by humans, and so has low nutritional value and counts as dietary fiber. Still, some species of bacteria in the gut are able to degrade pectin, and this process produces methanol.
This article reports measurements of methanol levels in the breath of subjects consuming pectin. Here, 10--15 grams of pectin (equivalent to ~1 kg of apples) was estimate to yield about 0.4--1.4 grams of methanol. The authors also state that there is a basal production of methanol in humans as well, of about 0.3 grams per day; the origin of this methanol seems unclear.
There are also pathways in human cells capable of forming methanol. This study demonstrates this fact by showing that infusion of ethanol (bypassing the gut) leads to a rise in methanol levels.
A recent review of metanol metabolism in humans can be found here.
I can't comment on dietary components or toxicity, but the Kegg database has an entry for methanol with links to the pathways in which it is an intermediate. You might find it useful to check that if you haven't already done so.