As the basic substance of life, 95% of choline in the human body is derived from lecithin. Therefore, lecithin is an indispensable nutrient. The human liver can secrete lecithin, but the secretion capacity gradually declines after the age of 30. Therefore, it is necessary to obtain sufficient lecithin from the diet. There is no clear recommended value for the intake of lecithin. Generally speaking, a reasonable diet can meet the needs of the human body (400-500 mg/day). But for some special groups, including children. Pregnant women, the elderly, students and other mental workers, diabetic patients, gallstone patients, smokers, long-term drinking or fatty liver patients, etc., need to increase the intake of lecithin in an appropriate amount.