Nutrition Science and Everyday Application - beta v 0.1

44 ALICE CALLAHAN, PHD, HEATHER LEONARD, MED, RDN, AND TAMBERLY POWELL, MS, RDN
automatically mean that your body is deficient in calcium and that you’ll definitely end up
with osteoporosis, because your individual calcium requirement may be less than the RDA.
However, since you probably don’t know your individual calcium requirement, the RDA is a
good target amount for consumption, and the more your intake drops below the RDA, the
greater your risk of later developing osteoporosis. The RDA is meant as a recommendation,
and meeting the RDA means it is very likely that you are meeting your actual requirement for
that nutrient.
It’s interesting to compare and contrast the EER (for energy or calorie intake) and the RDA
(for nutrient intake). In practice, both types of recommendations serve as a daily target for
intake. However, the EER is set to meet the average caloric needs of a person, while the
RDA is set to meet the needs of the vast majority of the population. Imagine if the EER was
set to ensure that it met the caloric needs of the vast majority of a population. It would
end up being a dramatic overestimate of caloric needs for most people. If everyone actually
followed this recommendation, the majority of them would consume far more calories than
they actually needed, resulting in weight gain. For nutrients, we have more flexibility in our
intake, because we have ways of storing or metabolizing and excreting excess nutrients, so
consuming somewhat more than our body needs is just fine.
Adequate Intake
When there is insufficient scientific evidence to set an EAR and RDA for the entire population,
then the National Academies committee can decide to set an Adequate Intake (AI) level
instead. The AI is based on observing healthy people and seeing how much of the
nutrient in question they are consuming. An AI is less precise than an RDA, but in the
absence of an RDA, the AI is our best guess of how much of a given nutrient is needed. If
there is not an RDA for a nutrient, than the AI is used as the nutrient-intake goal.
For example, there has not been sufficient scientific research into the exact nutritional
requirements for infants. Consequently, all of the DRI values for infants are AIs derived from
nutrient values in human breast milk. For older babies and young children, AI values are
derived from human milk coupled with data on adults. The AI is meant for a healthy target
group and is not meant to be sufficient for certain at-risk groups, such as premature infants.
Tolerable Upper Intake Levels
Consuming inadequate amount of nutrients can cause health problems, and we use the RDA
or AI values as targets to ensure that we’re getting enough. However, consuming too much
of many nutrients can also cause health problems. This is where the Tolerable Upper Intake
Level (UL) is helpful. ULs indicate the highest level of continuous intake of a particular
nutrient that may be taken without causing health problems.
It’s rare to find amounts of a nutrient exceeding the UL in a balanced diet based on whole
foods. However, a person who consumes dietary supplements, foods fortified with high
levels of additional nutrients (protein bars, for example) or a diet based on only a few foods,
might exceed the UL, and this could cause problems with nutrient toxicity. If you’re selecting
a supplement, be sure to choose one that does not exceed the UL for any nutrient, unless
this is under specific instructions from your doctor or a registered dietitian.
When a nutrient does not have any known issue if taken in excessive doses, it is not assigned