Tolerable upper intake level niacin

Hypervitaminosis Niacin. Niacin is considered nontoxic, and there are no Tolerable Upper Intake Levels based on its use as a vitamin. These refer only to niacin and niaci-... 

Sources Dietary Reference Intakes for Calcium, Phosphorous, Magnesium, Vitamin D, and Huoride (1997) Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin 85, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline (1998) EHetary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids (2000) Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc (2001) Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate (2005) and EHetary Reference Intakes for Calcium and Vitamin D (2011). These reports may be accessed via www.nap.edu A Tolerable Upper Intake Level (UL) is the highest level of daily nutrient intake that is likely to pose no risk of adverse health effects to almost all individuals in the general population. Unless otherwise specified, the UL represents total intake from food, water, and supplements. Due to a lack of suitable data, ULs could not be established for vitamin K, thiamin, riboflavin, vitamin B12, pantothenic acid, biotin, and carotenoids. In the absence of a UL, extra caution may be warranted in consuming levels above recommended intakes. Members of the general population should be advised not to routinely exceed the UL. The UL is not meant to ply to individuals who are treated with the nutrient under medical supervision or to individuals with predisposing conditions that modify their sensitivity to the nutrient... 

Abnormal accumulation in tissues and overloading of normal metabolic pathways, leading to signs of toxicity and possibly irreversible lesions. Niacin (Section 8.7.1), and vitamins A (Section 2.5.1), D (Section 3.6.1), and Bg (Section 9.6.4) are all known to be toxic in excess (see Section 1.2.4.3 for a discussion of tolerable upper levels of intake). 

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