"Rita" <[email protected]> schrieb im Newsbeitrag news:[email protected] >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).