Acorns are nuts and they’re abundant, but most people do not consider acorns a potential source of food. However, some world cuisines have relied or continue to rely upon acorns as a staple. People can eat acorns, and many do. The acorn is particularly valued in the cuisines of some North American indigenous peoples and of Korea.

It isn’t wise, however, to eat acorns as they are found upon the sidewalk, the way a chipmunk could. Raw acorns contain high concentrations of tannic acid, so their taste is bitter, and some varieties can in their raw state be toxic to humans. Even for the animals that eat acorns raw, the tannins in them can be irritating; for this reason, few animals eat acorns exclusively, and some acorn-eaters allow the nuts to soak for a time in water before they consume them. Processing acorns removes the tannic acid and makes them palatable. This starts with ripe acorns, those that have fallen from the tree of their own accord, or that fall readily with a light tap. Native Americans blanched the tannins from acorns by putting the shelled nuts in a bag, and letting the bag sit in the waters of a fast running stream. Boiling the nuts repeatedly, until the water no longer contains any trace of the brown tannic acid, accomplishes the same thing. The acorns can then be roasted just as other tree nuts are.

Once the bitter tannins are gone, acorns have a sweet and mild taste. People eat acorns simply dried or roasted, sometimes coating them with sugar to make candy. At times during the 19th century when coffee prices were exorbitantly high, roughly ground acorn served as a coffee substitute, though its flavor — reported as not the best thing ever — prevented it from becoming popular. Most often, people eat acorns in the form of a finely ground meal used to make breads and cakes or as a thickener in liquid-based foods.

For someone who wants to see what it’s like to eat acorns, a good first stop might be a Korean restaurant. Korean food allows people to eat acorns in the form of jellies and noodles made of acorn starch, which is what remains when the fiber of the acorn nut is removed during processing. Acorn starch features prominently these days only in Korean cooking, but it is a favorite part of that cuisine, and many Asian grocery markets sell it.

Another way to make acorns edible is by pressing them for oil, which constitutes almost a third of the weight of some varieties. The acorn oil used by North American hunters to attract animals and to mask their own scent in the woods is not made for eating, but the milder acorns of Europe and North Africa can produce an oil which is comparable in some ways to that of the olive.