The architects of cell membranes and the gifts of the ocean: the research frontiers of lecithin and a brief history of seaweed consumption.

Lecithin plays a vital role in the formation of biological membranes such as cell membranes and is also crucial for enzyme activity. It is also an important source of choline. The phosphate portion of the lecithin molecule is hydrophilic, readily binding with water, while its fatty acid portion is lipophilic, thus enabling it to form stable water-oil emulsions. Therefore, egg yolks can be used to make mayonnaise and in food processing. Furthermore, it is through this emulsifying effect that cholesterol in the blood is transported to the liver, preventing cholesterol from depositing on the blood vessel walls.

A molecule that possesses both hydrophilic and lipophilic (hydrophobic) components exhibits interfacial activity. Lecithin possesses this property, which is essential for the formation of biological membranes. When lecithin is suspended in an aqueous solution, it forms lipid vesicles that act as a double membrane. Cell membranes and other biological membranes are lipid double membranes. Lecithin, cholesterol, and other components of biological membranes are all part of these membranes. Foods rich in lecithin include egg yolks and soybeans.

Soybeans contain lecithin, whose fatty acids are all unsaturated linoleic acid, which helps improve lipid metabolism. The choline in lecithin, called acetylcholine, is a "raw material" for building excitatory neurotransmitters in the brain and nervous system, and is an essential component of the nerves responsible for memory and movement. According to research from the Department of Internal Medicine, Nishikawa School of Medicine, Niigata University, and the Department of Internal Medicine, Keio University, lecithin administration can lower blood cholesterol levels. Furthermore, according to research from the Department of Internal Medicine, Katsura School of Medicine, Niigata University, lecithin administration can alleviate symptoms of kidney disease.

Research from a group at the Faculty of Medicine, University of Tokyo, also indicates that lecithin is effective for patients with kidney disease. With changing lifestyles, the number of people in Japan suffering from cholesterol gallstones (cholesterol clumping in the body) is increasing. Studies have reported that gallstones can be dissolved with continuous use of lecithin in patients with cholesterol gallstones. Lecithin can also be used as a raw material for making digestible microcapsules, thus finding applications in the medical food field. Furthermore, new applications for lecithin are being explored.

Nippon Seika Co., Ltd. uses high-purity lecithin as the main raw material to create lipid artificial membrane vesicles, intending to utilize the functions of biomembranes in the pharmaceutical, cosmetic, and food industries. In 1992, it was used in a drug delivery system (DDS) to deliver drugs only to the target organ when manufacturing sustained-release drugs (which extend the effective time due to slow dissolution). The company is also researching how to apply lecithin to create easily absorbed functional foods from some poorly absorbed functional substances. As a major component of artificial membranes, lecithin is also widely used in research fields such as biomembrane research and membrane regeneration research.

Soy lecithin, refined from soybeans, has a distinctive odor when unprocessed, which limits its culinary applications. Dai Nippon Pharmaceutical Co., Ltd. has developed medicines for treating hyperlipidemia and food additives as emulsifiers using soy lecithin. They have also collaborated with an American company to develop "Lecithin AC," a popular children's product containing apple juice powder and cinnamon, and "Lecithin PC," containing pineapple juice powder or coconut milk powder. Surrounded by sea, Japan is a nation that considers seaweed and its processed products an important part of its diet.

Among the artifacts unearthed from the Inome Cave in Shimane Prefecture dating from the Jomon and Yayoi periods, fish bones and seashells were discovered, along with seaweed such as black kelp and Sargassum. Furthermore, black kelp was also found in peat remains at Kameoka in Aomori Prefecture. These facts prove that the Japanese were already consuming seaweed as early as the Jomon period. In the Yamato period, the Taihō Code was enacted in 701.