Vitamin A (retinol), beta-carotene The intake recommendations (D-A-CH reference values) of the German Nutrition Society (DGE) presented below are aimed at healthy people of normal weight. They do not refer to the supply of sick and convalescent people. Individual requirements may therefore be higher than the DGE recommendations (e.g. due to diet, consumption of stimulants, … Vitamin A: Intake
Function or effect of vitamin A derivatives. Substance group Function or effect Retinol Transport form, bound in serum to retinol binding protein (RBP) and transthyretin (TTR). 11-cis and all-trans retinal In the rhodopsin cycle of the eye Retinoic acid Inhibits tumor promoters and important for proliferation and differentiation of various tissues (intestinal mucosa/intestinal mucosa, respiratory … Vitamin A: Functions
Interactions of vitamin A with other micronutrients (vital substances): Zinc Zinc deficiency affects vitamin A metabolism in several ways: Decreased synthesis of retinol-binding protein (RBP). RBP is important for the transport of retinol via the bloodstream into tissues. Decreased activity of the enzyme necessary to convert the storage form of vitamin A – retinyl palmitate … Vitamin A: Interactions
According to the WHO, vitamin A deficiency is incipient at levels of 10 to 20 µg/dl and marked at levels below 10 µg/dl. Only when liver stores are depleted do plasma vitamin A levels also decrease, although there is a clear vitamin A deficiency in the tissues even before the plasma concentration is depleted. The … Vitamin A: Symptoms of Deficiency
Risk groups for vitamin A deficiency include individuals with: An extreme unbalanced diet or who practice certain diets. Maldigestion or malabsorption (in Crohn’s disease and celiac disease or indigenous sprue, respectively, ileojejunal bypass, pancreatic diseases, parenteral nutrition, chronic high alcohol consumption). Pregnant and lactating women are recommended to take 10% and 50% more vitamin A … Vitamin A: Risk Groups
The European food safety authority (EFSA) last evaluated vitamins and minerals for safety in 2006 and set a so-called Tolerable Upper Intake Level (UL) for each micronutrient, provided sufficient data were available. This UL reflects the maximum safe level of a micronutrient that will not cause adverse effects when taken daily from all sources for … Vitamin A: Safety Assessment
In the National Nutrition Survey II (NVS II, 2008), the dietary behavior of the population was investigated for Germany and it was shown how this affects the average daily nutrient intake with macro- and micronutrients (vital substances). The intake recommendations (D-A-CH reference values) of the German Nutrition Society (DGE) are used as the basis for … Vitamin A: Supply Situation
