Here’s a quick definition of RDIs — or RDAs as they are called in some countries.
Optimising Diets for Chronic Disease Risk
Other Standards in Nutrient Reference Values
- EAR (Estimated Average Requirement). A daily nutrient level estimated to meet the requirements of half the healthy individuals in a particular life stage and gender group.
- RDI (Recommended Dietary Intake). The average daily dietary intake level that is sufficient to meet the nutrient requirements of nearly all (97–98 per cent) healthy individuals in a particular life stage and gender group.
- AI (Adequate Intake – used when a recommended dietary intake cannot be determined). The average daily nutrient intake level based on observed or experimentally-determined approximations or estimates of nutrient intake by a group (or groups) of apparently healthy people that are assumed to be adequate.
- EER (Estimated Energy Requirement). The average dietary energy intake that is predicted to maintain energy balance in a healthy adult of defined age, gender, weight, height and level of physical activity, consistent with good health. In children and pregnant and lactating women, the EER is taken to include the needs associated with the deposition of tissues or the secretion of milk at rates consistent with good health.
- UL (Upper Level of Intake). The highest average daily nutrient intake level likely to pose no adverse health effects to almost all individuals in the general population. As intake increases above the UL, the potential risk of adverse effects increases.
- AMDR (Acceptable Macronutrient Distribution Range). An estimate of the range of intake for each macronutrient for individuals (expressed as per cent contribution to energy), which would allow for an adequate intake of all the other nutrients whilst maximising general health outcomes.
- SDT (Suggested Dietary Target). A daily average intake from food and beverages for certain nutrients that that may help to prevent chronic disease.
Supplementation has a role to play, but it needs to be done with caution, restraint and knowledge. The bottom line is that there will be individuals and population groups that do not meet the RDIs for individual nutrients.
- This can result from poor nutrition practices or even special diets poorly implemented. Low-carbers could be short on fibre and vitamin E; vegans on zinc, iron and B12; and very low-fat dieters on long chain omega-3.
- Populations in nutrient poor regions might lack iodine and selenium; and certain cultural habits like full body clothing can result in inadequate vitamin D intake in the absence of food or supplement sources.
- Athletes and heavy exercisers may need a modest increase in some nutrients, but this is usually accounted for by increased calorie intake — as long as the extra food is nutrient dense for the most part.
- Older people absorb vitamin B12 less well and this may require supplementation. The ill or infirm who do not get adequate sun exposure may require vitamin D supplements.
- Pre- and during pregnancy, folate supplementation is a useful reassurance against neural tube abnormalities.
However, not only is it likely wasteful to take mega-doses of supplements, it may even be unsafe. The recent scientific examination of vitamin E and beta carotene in high supplement doses has not yielded promise and has suggested adverse effects. If you feel you need to take an individual supplement or a multi, first check out the excellent information at the Office of Dietary Supplements at the NIH. then try not to exceed the RDI by more than a few times for any individual nutrient, unless there are indications that it’s safe and effective to do so.