Although a specific UL was not set for water, potassium, or sulfate, the absence of definitive data does not indicate that all people can tolerate chronic intakes of these substances at high levels. Like all chemical agents, nutrients and other food components can produce adverse effects if intakes are excessive. Therefore, when data are extremely limited or conflicting, extra caution may be warranted in consuming levels significantly above that found in typical food-based diets.
Suggested uses of Dietary Reference Intakes (DRIs) appear in Box S-2. For statistical reasons that were addressed in the reports Dietary Reference Intakes: Applications in Dietary Assessment (IOM, 2000) and Dietary Reference Intakes: Applications in Dietary Planning (IOM, 2003) and described briefly in Chapter 8, when a Recommended Dietary Allowance (RDA) is not available for a nutrient, the Adequate Intake (AI) is the appropriate reference intake value to use in assessing and planning the nutrient intake of individuals. Usual intake at or above the AI has a low probability of inadequacy.
When the median intake of a population group is equal to or exceeds the AI, the prevalence of inadequacy is likely to be low, especially when the AI is set at the median intake of a healthy group. This is the case for total water, in which the AI was based on median intakes of a population with little evidence of chronic dehydration. In the case of potassium, where the AI is set at a level much higher than the median intake, it is not possible to estimate the prevalence of inadequacy from survey data. It is only possible to assume that those whose intakes from food are above the AI are consuming sufficient potassium. It isn’t possible to speculate on the extent of inadequacy in those whose intakes are below the AI for potassium.
Chronic consumption above the UL may place an individual or group at risk of adverse effects. Therefore, the percent of survey individuals whose intakes exceeded the UL equals the percent of individuals whose diets would be considered excessive in that particular nutrient. For example, sodium intake data from the NHANES III (Appendix D), which collected 24-hour diet recalls for 1 or 2 days, indicate that: