Laver, a type of edible seaweed (notably Porphyra species), is used to support thyroid gland function primarily due to its high iodine content. Iodine is an essential micronutrient required for the synthesis of thyroid hormones, which regulate metabolism and are critical for proper thyroid gland function. There is substantial scientific evidence that adequate dietary iodine is necessary to prevent iodine deficiency disorders, including goiter and hypothyroidism. Seaweeds, including laver, are among the richest natural sources of iodine, sometimes providing more than 100% of the recommended daily intake in a single serving.

Multiple studies have measured the iodine content in various seaweeds and confirmed that regular consumption of iodine-rich seaweeds like laver can help maintain healthy iodine status, especially in populations at risk of deficiency. However, it is also noted in scientific literature that excessive intake of seaweed can lead to excess iodine consumption, which may disrupt thyroid function in susceptible individuals. Thus, while there is strong scientific validation for the use of laver as a dietary source of iodine to support thyroid health, moderation is important.

The use of laver as a food with health benefits, particularly for thyroid support, is supported by both traditional consumption patterns in East Asia and modern nutritional science documenting its iodine content and physiological effects.