3 replies to this topic

[blackshugar]

I just wanted to know if the RDA includes absorption rates for all the nutrients in its recommendations. For example, it recommends 1000 mg of calcium per day, so does that include the fact that we absorb on average only a third of it from our diet and hence we need only 300 - 400 mg of it considering the bioavailability? Or does it require us to absorb a total of 1000 mg? Any help is appreciated.

[Darryl]

There's public documentation of the process behind nutrient recommendations. For U.S. RDAs, the Dietary Reference Intakes series arise from subcommittees of the U. S. Institute of Medicine's Food and Nutrition Board, mostly published between 1997 to 2005. The World Health Organization has comparable (though more consise) publications on vitamins & minerals, and protein, which often rubber-stamp the US recommendations but I find more trustworthy in some cases, due to lesser food industry lobbying.

 

Where there in quantitative evidence for requirements (in some cases, still poorly defined), the studies typically come from metabolic wards where volunteers are fed nutrient deficient synthetic diets until some acute adverse physiological effect is detected. These hence would already account for oral bioavailability, but only from rather unnatural diets. Where deficiency diseases are absent in the "wild", some requirements assume even the lowest percentile intake in the general population is sufficient. And some requirements come from adverse effects seen in nutrient deficiencies in intravenous/parenteral nutrition. In all cases, there are substantial fudge factors (for example, the US RDA's are typically 20% above the 95% percentile requirement) that reflect the uncertainties.

Edited by Darryl, 02 January 2016 - 01:07 AM.

[blackshugar]

@Darryl Thanks for replying but that's not a very direct answer to my query. I'm still clueless.

[kurdishfella]

No. And women need less nutrients since their body requires less to maintain so they are generally healthier than men. (unless pregnant and older or immune defiency etc than more) . ALso the rda is different slightly everywhere. I prefer recommended every 2 day allowance as its more towards the natural way

Edited by kurdishfella, 27 October 2021 - 03:29 AM.