Dietary reference intakes, report 4: Vitamins A and K

Regarding vitamin A the Estimated Average Requirement (EAR) has been based on the assurance of adequate stores. Retinol equivalents (RE) have been replaced by retinol activity equivalents (RAE). For dietary provitamin A carotenoids - only beta -carotene, alpha -carotene, and beta -cryptoxanthine may be taken into consideration - RAE have been set at 12, 24 and 24 mug. This means that, in terms of RAE, vitamin A activity of provitamin A carotenoids is half the vitamin A activity in terms of RE (i. e. Food and Nutrition Board 1989, DACH Societies for Nutrition 2000). It also means that a larger amount of pro-Vitamin A carotenoids is needed to meet the vitamin A requirement, and that in the past vitamin A intake has been overestimated. The RDA for men and women now is 900 and 700 mug of RAE/day instead of 1,000 and 800 mug of RE/day (RDA 1989, DACH reference values 2000). The Tolerable Upper Intake Level (UL) for adults is generally set at 3,000 mug preformed retinol/day. Because of the lack of data to estimate an EAR for vitamin K, an Adequate Intake (AI) is set based on representative dietary intake data from health individuals in the United States. The AI for men and women is 120 and 90 mug/day, resp. The common formula (1 mug/kg BW/day) and the prothrombin time formerly used as indicator of vitamin K status for setting RDA (1989) and recommended intakes (DACH Societies 2000) are not regarded as an adequate basis to estimate an EAR and RDA. No adverse effect has been reported for individuals consuming high amounts of vitamin K, so an UL was not established. Although observational epidemiological studies suggests that higher blood concentrations of beta -carotene and other carotenoids and higher amounts of dietary vitamin K are associated with a lower risk for several chronic diseases, evidence is not regarded as sufficient to support a required percentage of dietary vitamin A from provitamin A carotenoids and more dietary vitamin K to meet the vitamin A and K requirement.