We are told to follow the RDI for a variety of nutrients. This is repeated over and over by teachers, guides, nutritionists, medical doctors and so on. However, when asked, no one can provide me with the actual source of how they came to this conclusion about RDI.

Who calculated this and using what scientific method exactly? Looks like a shot in the dark to me.

Where can I look at a study that proves that a human eating less than RDI will become deficient (showing clinical symptoms of deficiency of a certain vitamin or mineral)?

1 Answer 1


Assuming that you are asking about the US, the documents explaining the RDA (recommended dietary allowance), AI (adequate intake), and UL (tolerable upper intake level) are available on the website of the National Institutes of Health. They are written by "The Food and Nutrition Board, Institute of Medicine, National Academy of Sciences".

Going into these in detail is way too broad because these are long - for example, there is a 1000 page document on the RDI of calcium and vitamin D. Far from being "a shot in the dark", this details a lot of the research those values are based on.

It also says when insufficient data is available to establish these values (for example RDA for calcium for infants). Far from being only the value you might see on the label of your food, the recommendations are are actually different for different age groups, sexes, and life stages (for example pregnancy), as can be seen in the detailed recommendations for vitamin D and calcium, for example. The quality needs to be judged for each individual recommendation, there is no single definitive answer.

Where can I look at a study that proves that a human eating less than RDI will become deficient

The reasoning behind the AI should be listed in the documents I linked to. For calcium in adults, for example, the AI is based on Calcium requirements: new estimations for men and women by cross-sectional statistical analyses of calcium balance data from metabolic studies.

Be aware, though, that "proving" this isn't as straight forward as you might think it is. You can't just deprive people of a nutrient and look at what happens - a study like that will usually be considered unethical. Instead, researchers look at what people with existing symptoms of malnutrition are ingesting, for example.

  • I do not want the details on stack exchange, I would like a link to those documents so I can see for myself. Making a 1000 page document about something doesn't make it right, I'd like to see for myself, especially after reading this: en.wikipedia.org/wiki/… which indicates there is something significantly lacking there. We are being told "as fact, every day you must" and I'm quite suspicious of that, having seen people thrive on diets that have about half the calcium required according to those guidelines.
    – U0001
    Commented Mar 30, 2016 at 2:19
  • And I definitely agree with you, because of ethical reasons we cannot test on twins and therefore cannot get a definitive answer. I think what I'm really after is some way of building an argument where micronutrient requirements should be looked at on a longer basis, say monthly, instead of creating something that is almost impossible to achieve daily without overeating. I'm finding that hitting 100% target on daily values is just unrealistic and the human race wouldn't have survived if that was the case.
    – U0001
    Commented Mar 30, 2016 at 2:27
  • 2
    " I would like a link to those documents so I can see for myself." Which I gave you. Is there anything missing? "and the human race wouldn't have survived if that was the case." malnutrition does not mean people die. Lots of people have a vitamin D deficiency, for example. And iron deficiencies. That means their health isn't optimal, that they may be more tired than the would be otherwise, maybe get sick more often, not that they die....
    – YviDe
    Commented Mar 30, 2016 at 5:05
  • Some of your links are 404, others lead to paywalled articles when they are open-access'ible elsewhere.
    – user10901
    Commented Mar 12, 2021 at 18:13

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