"Rita" <[email hidden]> schrieb im Newsbeitrag
news:[email hidden]...
Quoted message said:I have been wondering how those producing the nutrition
guidelines determine certain recommendations, such as
the grams of fiber one should strive for each day.
Can this vary by age and weight and other factors as well?
Eating say, x number of servings of vegetables each day
is recommended, but how large need those servings be?
Is there individual variation on this?Just how are these nutrition guidelines determined?
Are they tested and with what population? Or are they
simply a "best guess"? I'd really like to have some
information on exactly what the process is of
determining these guidelines before they are released
to the public?
Apart from various conspicion theories: recommendations come from available
scientific material, local particularities and political decisions.
Some RDI's are derived from plasma levels of vitamins in healthy people,
others from known deficiencies and toxicity levels of a certain
micronutrient, and others are estimated by looking at the average intake and
at the incidence of deficiency and so on. This means that for some vitamins
the RDI's are well established because the scientific material is dense
while others are just "best guesses" as you said.
The RDI's are a political issue as well.. this covers mostly health politics
and prevention.
RDI's are valid for the healthy average human being (average in terms of
activity etc) for a certain age group and sex per definition. This means the
RDI's are average recommendations for groups- not exact numbers for
individuals- unfortunately this is often overlooked.
If I am not mistaken the detailed description of each nutrient and the
studies that its RDI is based on is published with the RDI's and should be
available. At least it is so for most other industrialized countries.. i
guess it should be the same in the US (assuming you are from there).