Life Extension Magazine®

Issue: Apr 2001

Dietary Reference Intakes

Analyzing the unsubstantiated claims recently made about supplement intake.

Scientifically reviewed by: Dr. Gary Gonzalez, MD, on January 2021. Written By Charles Platt.


At the beginning of this year, the Associated Press circulated a vitamin scare story that was picked up by numerous newspapers, magazines and TV stations across the country. The story reiterated some shocking but totally unsubstantiated claims, including a warning that “more than 1,000 milligrams a day of vitamin E-or 1,500 international units-could cause uncontrolled bleeding.”1

The source of this story dated back almost a year to a series of books published by the National Academy of Sciences. The titles include Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium and the Carotenoids,2 and Dietary Reference Intakes: A Risk Assessment Model for Establishing Upper Intake Levels for Nutrients.3 As Life Extension Foundation reported in August, 2000, the purpose of these books was to establish a complex new set of guidelines replacing the old RDA (Recommended Daily Allowance) for vitamins. The books summarized work by the Food and Nutrition Board, a unit of the Institute of Medicine, which is part of the National Academy of Sciences. The Academy is a private nonprofit corporation created by an Act of Congress, with a charter signed by Abraham Lincoln in 1863. Today, it is funded largely by federal agencies such as the National Institutes of Health, the Department of Agriculture, and the FDA.4

While many magazine buyers and TV viewers may have assumed that they could trust such a prestigious institution, Life Extension readers knew better. We meticulously rebutted each of these attacks against dietary supplements in the August 2000 issue of Life Extension magazine. Our conclusion was that “the government is still committed to disseminating false and misleading information against dietary supplements.”

This is no exaggeration. Government-funded bodies such as the Academy have mounted a persistent campaign using scare tactics to discredit the beneficial properties of vitamins, minerals and other supplements.

Seemingly, this makes no sense. Why would scientists with impressive credentials try to alarm the public if there is no valid reason for doing so? Why would agencies that were established to protect us try to prevent us from enhancing our health? And why should journalists be so willing to believe establishment “health authorities” and circulate scare stories, with little or no supporting evidence?

RDAs were established many decades ago, in 1941, when the Food and Nutrition Board set a minimum daily intake that would prevent serious conditions such as scurvy and rickets.5,6 Thus, the initial purpose of RDAs was important and valid: To educate the public about terrible diseases and lifelong deformities caused by severe malnutrition.

Decades passed. Americans became more prosperous and diet-conscious, and vitamins were mixed into basic foods such as bread, milk and breakfast cereal. Consequently, ailments such as scurvy and rickets started to disappear. Today, as virtually no Americans suffer the terrible conditions that existed half a century ago, RDAs are far less important than they used to be.

The concept of an RDA also is less relevant because we’ve learned that people’s needs may vary. Elderly people and cigarette smokers may benefit from a higher vitamin intake than, say, college students. Exposure to sunlight can reduce your need for vitamin D, while oral contraceptives decrease serum levels of vitamin C. Such diversity invalidates the “one size fits all” approach of a single, minimum daily vitamin requirement.

Like any large, old, conservative institution, the National Academy of Sciences is slow to change. It tinkered with RDA numbers over the years, grudgingly upgrading some of them from time to time. Finally, soon after 1994, it started rethinking the whole system.

The year 1994 just happened to be when Congress passed the Dietary Supplement Health and Education Act, which guaranteed freedom of choice for consumers and restricted the FDA’s regulatory power. Possibly, the National Academy of Sciences felt a need to be more active in protecting consumers from themselves, since the FDA had been prevented from doing so.

The Food and Nutrition Board (which, you will recall, reports to the Institute of Medicine, which is a part of the National Academy of Sciences) set to work. To its credit, it recognized that “one size fits all” didn’t make sense anymore, and it defined as many as twenty-two different social groups needing different levels of nutrition, mainly determined by age and gender.7Then it created three new dietary measurements: the Estimated Average Requirement (EAR), Adequate Intake (AI), and Tolerable Upper Intake Level (UL). These bewildering acronyms were added to the RDA under one all-embracing term: Dietary Reference Intakes.8


Certainly, establishing different RDAs for people with differing needs was a step in the right direction. However, if we cut through the jargon and take a hard look at the measurement methods, we find that they are archaic, inaccurate and misleading.

First, the Board selects a group of people, such as males aged 19 to 50. Then it looks at just one vitamin and finds a minimum level which is so low, it will cause half of this group to suffer deficiencies. This minimum level is defined as the EAR-the Estimated Average Requirement.

Next, the Board uses a formula to calculate the RDA from the EAR. It can be as simple as: RDA = 1.3 x EAR.

This may seem arbitrary, but the system makes even less sense in cases where the Board cannot measure the EAR. Remember, the EAR is so low, half the people consuming vitamins at that level will suffer deficiencies. How do you establish this in modern America? In some cases, you can’t.

Since the EAR must be measured before the RDA can be calculated from it, if the Board can’t measure the EAR, they’re stuck. To get around this, the Board invented a different number: The Adequate Intake (AI). This is a guesstimate derived by examining healthy people and noting their vitamin consumption.9

On this flimsy foundation, the National Academy of Sciences published its supposedly authoritative books advising hundreds of millions of consumers about their vitamin intake. In reality, the “minimum needs” cited in these books are hopelessly out of step with modern America, because they are still based on the 1940s concept that we need just enough vitamins to avoid serious deficiencies. Clearly, this is an obsolete concept. To take just one example, we don’t need to know the minimum amount of vitamin C to avoid scurvy; we need to know the higher dose that may be effective as an antioxidant, especially in combination with other supplements, to reduce our long-term risk of age-related diseases.

Because the Academy’s publications are filled with charts, tables, and citations, readers may not even understand the underlying, primitive system that has been used to “calculate” minimum requirements. Consumers also may be misled by the Tolerable Upper Intake Level (UL) cited for each supplement. Supposedly, this is the maximum level to avoid side effects; yet the number takes no account of real-world variables.

Niacin, for instance, is assigned a UL of 12 to 18 mg for adults of various ages,9 to avoid the “flushing and itching” side effect. Yet anyone who uses niacin knows that some people are far more susceptible to the “niacin flush” than others, and the effect can be reduced or eliminated if you take the supplement with food. Also, regular users can find that their initial reaction to niacin diminishes over a period of time, as they become accustomed to it. There is no scientific basis to suggest that one Tolerable Upper Intake Level can be established for any age group.

The Food and Nutrition Board, and its various subcommittees, took five years to complete its federally-subsidized overhaul of the RDA. Originally the project was budgeted at $5.4 million; the final figure is not yet available.10

This money has been wasted. The new RDA numbers are still pegged at levels so low, they barely protect consumers against serious consequences of malnutrition. For 99% of the American population, this information is worthless. Moreover, even if the RDA levels were raised somewhat, they would still have little relevance, since each minimum requirement is established separately for each vitamin. This ignores the synergistic effects that occur when several different supplements are taken at one time.

The National Academy of Sciences does admit, in its publications, that some research suggests therapeutic effects from elevated doses of vitamins. For instance, the Academy cites research showing that vitamin E can reduce the risk of heart disease. But the Academy still refuses to recommend that you increase your intake of vitamin E, because that would conflict with its basic mission, setting the absolute bare minimum level to avoid the consequence of a major deficiency-in this case, peripheral neuropathy, which the authors admit is virtually unknown.11


How can a respected scientific institution persist in denying reality? Perhaps the National Academy, and its sponsors such as the FDA, are reluctant to admit that they may not be the ultimate authorities on nutrition anymore. The use of supplements has been a grass-roots movement, in which a small minority of health professionals, a few independent manufacturers, and a vast army of consumers have led the way. Large institutions and regulatory agencies prefer to see themselves as advising consumers, not receiving advice from consumers. The idea that we may be better informed than they are must be hard for them to accept.

Meanwhile, in the mass media, journalists often lack information about supplements, and they work under deadline pressure which doesn’t allow enough time to dig up the facts. Journalists rely on advice from “health authorities,” and they base their stories on press releases from institutions with impressive names. Worse still, a journalist often is writing for an editor who wants a scare story, because magazines sell more copies, and TV stations attract more viewers, when they scare people instead of reassuring them. This explains how a trusted organization such as the Associated Press ends up distributing a warning about the dangers of vitamins, unsupported by any references.

But a scare story doesn’t just help the media to grab audience share. It also helps institutions and regulators who have to justify their continuing existence. Suppose, for a moment, that those of us who use supplements really do know what we’re doing, and we aren’t being duped by an unholy alliance of corporations and radical health advocates. If this is true-do we really need the National Academy of Sciences and the FDA to look after us?

Clearly, regulators and “health authorities” have a powerful incentive to make us feel fearful, so that we will continue to want their protection. This ulterior motive is worth considering the next time you see a news agency quoting a venerable institution that is trying to warn us about “the dangers of vitamins.”

To review The Life Extension Foundation’s meticulous rebuttal to The National Academy of Sciences’s attack on dietary supplements, refer to the August 2000 issue of Life Extension magazine.


  1. The claim was uncritically reproduced, for example, in “First, Vitamins Were our Saviors; Then the Real Truth Came Out” by Rowland Nethaway, Cox News Service, April 15th, 2000, archived at
  2. National Academy Publications at
  3. National Academy Publications at
  4. See
  5. Norman I. Krinsky, Chair, Panel on Dietary Antioxidants and Related Compounds, quoted in
  6. Johns Hopkins Magazine, April, 1998, archived at
  7. National Academy Publications at
  8. Standing Committee on the Scientific Evaluation of Dietary Reference Intakes, Food and Nutrition Board, Institute of Medicine, at
  9. National Academy Publications at
  11. National Academy Publications at