A Sour Note on Sour Power
Vinegar is an acid and if placed in metal goblets, even for a short time will begin to dissolve many metals. Lead, copper and aluminum, iron are common examples. While the body needs iron, it can do without most other metals that dissolve in vinegar.
There have been reports of several unintentional vinegar related poisonings in San Diego. It seems that tourists often purchase the beautiful pottery when they visit Tijuana, Mexico. The bright colored glazes that are used on those products contain lead. Failure to fire the pottery at a high enough temperature leaves lead oxides and salts on the surface. The vinegar in foods like salads and salsa mixes will leach out the lead if the food is served in those dishes.
Ingestion of this lead will cause a mild case of heavy metal poisoning. Long term ingestion of lead will not only cause you to gain weight, it could drive you so nuts you might start enjoying heavy metal music.
It you cook with vinegar, or other acids, in aluminum you will likely notice that the pots develop small holes. You may want to ask, "where did the disappeared metal go?"