Shiso was originally used as a sedative in eastern medicine. It has calming effects on the body and in sushi,it is used to lessen the taste of some ingredients that are overpowering.
Shiso leaves, seeds, and sprouts are used extensively in Japanese cuisine. Green leaves, called aojiso are used as herb in cold noodle dishes (hiyamugi and sōmen), cold tofu (hiyayakko), as well as tataki and namerō.
Aojiso is also served fresh with sashimi. It is also used as a savory herb in a variety of dishes, even as a pizza topping (initially it was used in place of basil).
Purple leaves, called akajiso are used to dye umeboshi (pickled ume) red or combined with ume paste in sushi to make umeshiso maki. It can also be used to make a sweet, red juice to enjoy during summer.
Shiso seed pods are salted and preserved to be used as a spice, while the germinated sprouts called mejiso are used as garnish. The inflorescence of shiso, called hojiso , is used as garnish on a sashimi plate.
An inflorescence of shiso, called hojiso, is typically used as garnish on a sashimi plate; the individual flowers can be stripped off the stem using the chopstick, adding its flavor to the soy sauce dip.
The fruits of the shiso, containing fine seed (mericarp), can be preserved in salt and used as a spice or condiment. Young leaves and flower buds are used for pickling in Japan and Taiwan.
It can also be used with lighter tasting ingredients to enjoy the aromas of the shiso as well. The aromas mainly come from perillal dehyde and is often used in perfumes as well.
Some shiso cultivated outside of Japan have a high content of perilla-ketone which may cause pulmonary emphysema in some small animals. As the leaves look identical, so caution should be taken for people who have respiratory problems.