Laver (gim)

Gim is laver, a red seaweed of the family Bangiaceae. Its blades are only one cell thick, shaped like a bamboo leaf or a rounded sheet, and they appear on the rocks in the cool water of autumn through spring. The Encyclopedia of Korean Culture counts around ten species in Korean waters. Older texts call it haeui or jachae; the term haetae is a Japanese-influenced usage.

Laver appears in Korean records as a local product in the 15th-century Gyeongsang-do jiriji and, by the 1530 Sinjeung dongguk yeoji seungnam, it was listed as a specialty of dozens of districts. Cultivation is the oldest form of aquaculture in Korea. Several stories credit its start to the 17th century; the best known names Kim Yeo-ik (1606–1660), who settled on Taein Island near Gwangyang in 1640 and is said to have noticed laver growing on driftwood branches and begun planting stakes in the tidal flats. Local tradition even holds that the name gim comes from his family name. His story survives in a family genealogy, and the site was designated a South Jeolla provincial monument in 1987.

Farming spread along the south coast in the late Joseon period, first on stakes and brushwood, then on bamboo screens first developed in Wando, and later on floating nets, which greatly raised yields. The industry grew rapidly in the colonial era, driven partly by strong Japanese demand, and today serves a large domestic market as well as overseas buyers.

Plain sheets are toasted and used for gimbap and for wrapping rice at the table. Brushed with sesame or perilla oil, salted and toasted, they become gim-gui; laver is also made into jaban and fried bugak. Folk custom held that wrapping rice in gim on Jeongwol Daeboreum, the first full moon of the lunar year, would keep the eyes bright.

• Concentrated nutrients in a light food: Because it is dried, laver is dense in protein, fiber, vitamin A and folate by weight, although a typical serving is only a sheet or two.
• A source of iodine — mind the total: The Korean Food Composition Table lists about 3,800 µg of iodine per 100 g of dried gimbap laver. MedlinePlus notes that iodine is needed for thyroid hormones but that very high intakes can reduce thyroid function; people with thyroid conditions, or who take thyroid medicine, should ask a clinician how much seaweed is right for them.
• Vitamin B12 is under study: The table lists substantial vitamin B12, and a small 2024 trial in 30 vegetarians found that 5 g of nori a day for four weeks improved blood markers of B12 status. The evidence is still limited, so it should not replace medical advice on B12 for people who eat no animal foods.
• Vitamin K and blood thinners: Dried laver is rich in vitamin K. MedlinePlus advises people taking warfarin to eat consistent amounts of vitamin K–containing foods from week to week.
• Seasoned gim adds salt and oil: Snack-style and gim-gui sheets are brushed with oil and salt, so they contribute more sodium and fat than plain laver.