How much vitamin A do people need?
There is no simple answer to this question. The Institute of Medicine set the recommended dietary allowance (RDA) at 900 mcg for men and 700 for women (equivalent to 3,000 IU for men and 2,333 for women). RDAs are a minimalist approach to nutritional needs. They are designed to prevent deficiency diseases in 95% of the healthy population. However, some doctors believe the official RDA may not be enough to maintain optimal health. Dr. Elson Haas (medical director of the Preventative Medical Center of Marin in San Rafael CA, author of many books and a leading practitioner of integrative medicine) says, “Vitamin A is needed at a level of at least 5,000 IUs per day, though this may vary due to many factors. . . . Analysis of the average American diet reveals that it provides only about 4,000 units of vitamin A daily, so the many problems of vitamin A deficiency, such as visual changes, skin dryness, and increased infections, are more common than most people realize.” As pointed out in Supp
