Vitamin health intake levels

Upper intake level (UL) of vitamins. The UL is defined as the highest level of intake of a nutrient that will not pose a risk of adverse health effects to most individuals in the general population. The UL is an important reference standard, especially with the current promotion and wide availability of vitamin preparations. A table of the DRIs for vitamins is available on the lOM s web site at http //www.nationalacademies.org/IOM/IOMHome. nsf/Pages/Ongoing+Studies FNB. 

Scientific Committee on Food (2000) Opinion of the Scientific Committee on Food on the Tolerable Upper Intake Level of Vitamin Bg. Brussels European Commission Health and Consumer Protection Directorate-General. 

In Pauling s view, the system worked well as long as the local diet provided the necessary high levels of vitamin C. But as these primates moved out of their tropical valley, their health began to suffer as their vitamin C intake went down. Their dietary intake of vitamin C was no longer enough to replenish the natural levels their bodies had once produced internally. 

The optimal dietary requirements of vitamin E for humans are not yet known, especially with the emergence of new paradigms regarding adequate levels of dietary micronutrients (Chalem, 1999). Recommendations in the United States and Canada have been reevaluated, and a new concept of Dietary Reference Intake (DRI, 2000) was issued for vitamin E and other antioxidants. The DRI recommendation should prevent specific deficiency disorders, support health in general ways and minimize the risk of toxicity, which carries more tasks than the previous recommendations (DRI, 2000). Accordingly, the recommendations for intakes were set to higher levels than previously. Estimated Average Requirements (EAR) for adults, both men and women, were set to 12 mg a-tocopherol/day, RDA to 15 mg/day and Tolerable Upper Intake Level (UL) to 1000 mg/day. Moreover, the EAR and RDA are based only on the 2R-stereoisomeric forms of a-tocopherol, because the other vitamers... 

Weber, P., Bendich, A., and Machlin, L.J. 1997. Vitamin E and Human Health Rationale for Determining Recommended Intake Levels. Nutrition. 13 450-460. 

A Tolerable Upper Intake Level (UL). The UL is the maximum intake by an individual that is unlikely to pose risks of adverse health effects in almost all (97-98%)individu-als. It includes intake of a nutrient from all sources (food, fortified food, water, and sup-dements). Water can include fluoride and minerals depending on the source of water. "Tolerable" is used to "avoid implying any possible beneficial effect." It is the amount of vitamin that can be "tolerated" without the person s exhibiting or experiencing adverse reactions. The UL should not be considered the upper dose for those who self-dose with megadoses of vitamins. 

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 individutils in the general population. Unless otherwise specified, the UL represents total intake from food, water, and supplements. Due to alack of suitable data, ULs could not be established for vitamin K, thiamin, riboflavin, vitamin B, 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 apply to individuals who are treated with the nutrient under medical supervision or to individuals with predisposing conditions that modify their sensitivity to the nutrient As preformed vitamin A only... 

In the Health Professional Follow-Up Study (Rimm et al.y 1993) vitamin C intake could not be related to CHD morbidity however, a significant inverse relationship was found with vitamin E. In a study in Finland with about 5000 men and women, dietary intake of vitamin C was inversely related to coronary mortality only among women. In this study, vitamin E intake was inversely related to coronary mortality in both men and women. A substudy of the Baltimore Longitudinal Study of Aging with 827 participants showed that high levels of vitamin C were associated with less atherogenetic lipid profiles (Hallfrisch et al., 1994). 

Recommended dietary allowances (RDA) for the US and Canada were recently revised by the Institute of Medicine (lOM). Owing to the serious, potentially irreversible, effects caused by an excess of vitamin A, guidelines were also established for a tolerable upper intake level (UL), defined as the highest intake of a nutrient that is likely to pose no risk of adverse health effects in nearly all healthy individuals. The 2001 RDA and UL for vitamin A for various life stages are listed in Table 2. 

Along with increasing evidence of health benefits from consumption of vitamins at levels much higher than RE) A recommendations comes concern over potential toxicity. This topic has been reviewed (19). Like all chemical substances, a toxic level does exist for each vitarnin. Traditionally it has been assumed that all water-soluble vitamins are safe at any level of intake and all fat-soluble vitamins are toxic, especially at intakes more than 10 times the recommended allowances. These assumptions are now known to be incorrect. Very high doses of some water-soluble vitamins, especially niacin and vitamin B, are associated with adverse effects. In contrast, evidence indicates that some fat-soluble micronutrients, especially vitamin E, are safe at doses many times higher than recommended levels of intake. Chronic intakes above the RDA for vitamins A and D especially are to be avoided, however. 

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