Perhaps in the case of fiber and bowel health – The RDA for fiber does at least reference bowel health, though not optimal bowel health. On the other hand, however, the nutritional requirement for fiber is perhaps bogus (as a fiber-free diet is workable – if indeed the Masai tribe studied by Weston Price was healthier and fitter than we fiber- eaters). At any rate, fiber is a mixed blessing even in bowel health; yes, soluble fiber feeds the flora somewhat selectively and can help optimize its composition and yes, the insoluble fiber bulks stool, but the more bulk there is, the more hydration and motility is needed to push it through. Sadly, Americans are generally poorly hydrated and deficient in nutrients that promote good motility (like magnesium), and because of this, more fiber per se is self-defeating in Americans. Proper hydration and proper motility are the really important things in bowel health; fiber is of secondary importance.
But for all other nutrients:
No – firstly, because RDAs are not determined with any optimal health parameter in mind. Secondly, the government scientists tend to look at anything passing to waste as purely and simply waste, when it is far from it, until it actually passes through. Obviously even something circulating through the body (think of uric acid, bilirubin, vitamin C) on the way to being urinated out can do a world of good, and obviously colonic contents contain nutrition for the flora and the intestinal epithelium long before they becomes waste. Waste cannot even be called “waste” until it is actually excreted, and up to that point the concentration of nutrients and their biological activity could have been important for something even if the majority of these nutrients are going to end up being excreted.
And an acidic urine, including urine made acidic by high levels of vitamin C supplementation, by virtue of harming resident bacteria in the ureter, cannot even be called waste while it is passing through. It is not tarnal waste until it enters the toilet, if then!
Besides fiber, I doubt the government scientists factor bowel or urinary system health into the equation, because I do not think that such matters are even a consideration, unless some nutrient deficiency was actually correlated to an increased incidence of some type of bowel or urinary tract disease.
Yet the bowel does not have to be diseased to be dysfunctional and it does not even have to be dysfunctional to be far short of optimal performance.
For example, constipation is the most common problem in which the bowel is not at optimal performance; for some constipated people, constipation is not necessarily even a bowel dysfunction, and only rarely is constipation a consequence of disease.
As an example of an RDA that may be set too low because bowel health is not even considered, consider magnesium.
The RDA for Mg is about 350 mg. Of this about about 100 mg is absorbed by the intestines and 100 milligrams is excreted by the kidneys each day, maintaining bodily balance. Is 250 mg of magnesium, some free, some complexed with various counterions, passing through the gut enough even for optimal intestinal motility? Could that low an unabsorbed level of magnesium, depending on complexation and other critical factors, be somewhat constipating? It is possible, but I am not aware of anyone even looking at it. The effect of a higher plasma magnesium concentration on the prevention of kidney stones has been looked at peripherally.
If this analysis is correct, provided there are no toxicities associated with these levels, the proper RDA for nutrients is given by the sum of at least 3 terms:
- the amount necessary to maintain optimal body balance
- The amount necessary for optimal bowel health
- The optimal amount that needs to circulate through the body and then be excreted by the kidneys.
For Mg = the RDA for the bowel + the RDA for the urinary system + the RDA for the rest of the body. The last term is given by the amount to maintain bodily pools at functional levels. The first term has to provide proper bowel motility and contribute to proper hydration, and no doubt more magnesium is needed, the higher the diet is in bulking (insoluble) fiber and the lower it is in water.
For vitamin C, the same is true – the vast majority of the total requirement may be for #2 and #3, that is, for bowel health (including the anti-constipation effect of excess bowel vitamin C, the anti-oxidative effect of vitamin C, especially in a higher fat diets) and urinary system health, which would explain why the government sees only 60 mg as necessary and why Pauling saw many grams as required.