All About the Foods We Eat / Why You Should NOT Depend on the RDA

submitted by Dr. Gary Farr Last Updated October, 15, 2002

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The first Recommended Dietary Allowances were established in the United States in the 1940s to provide standards for good nutrition. The allowances were not considered permanent, but rather recommendations based on the best available scientific knowledge. Since 1943 the RDAs have been revised approximately every five years as new data became available. In 1985, the RDAs came under attack by segments of the scientific and medical community as not serving the needs for establishing optimal nutrition.

What are the RDAs? They are defined as "the level of intake of essential nutrients considered in the judgment of a government nutrition board on the basis of available scientific knowledge to be adequate to meet the known nutritional needs of practically all healthy persons." What adequate means is a point of contention surrounding the RDAs. Does adequate mean a margin of protection against the nutritional deficiency diseases like scurvy in the absence of vitamin C, beri-beri in the absence of vitamin B1 or B2, or pellagra in the absence of vitamin B3? Or does adequate imply good health? These are questions which have framed the basis of the debate today that swirls around the RDAs.

Secondly, questions have been raised as to who "practically all healthy persons" are. Individuals who do not fall into this category include:

1. People engaged in heavy work or physical exercise which increases their energy and nutrient needs.
2. People who live in very warm or cold climates who may require special levels of certain nutrients.
3. People who are aging and as a consequence have specific nutrient requirements.
4. People with specific kinds of health problems such as metabolic disorders, chronic diseases and injuries.
5. People consuming drugs or alcohol, people who have undergone recent surgery, people suffering from illnesses, trauma, burns, intestinal diseases or other unique genetic requirements.

What is meant by optimal versus adequate nutrition? In 1985 the United States Food and Nutrition Board recommended to the National Academy of Sciences revisions for the 1980 RDAs. In 1986, however, Dr. Frank Press, chairman of the National Academy of Sciences, stunned the nutritional community by failing to accept the recommendations of the Food and Nutrition Board. In a letter from Dr. Press to Dr. Wyngaarden, then chairman of the National Research Council, Food and Nutrition Board, Dr. Press comments, "Our decision not to accept the revisions of the RDAs at this time stems primarily from an impasse that resulted from scientific differences of opinion between the committee and reviewers from the Food and Nutrition Board related to assumptions about the indications of good health." He goes on to say that "Most reviewers from the National Academy of Sciences believe that modification to the RDA are justified in the face of compelling new evidence not merely as a result of reinterpretation of existing data based on assumptions." - He also stated that, "The decision not to accept the recommendation was based upon the deepening understanding of the interplay between nutritional factors and health, especially the importance of these factors in the aging process and susceptibility of the older people to chronic diseases. Scientific developments in the past five years relating nutrition to health need be more seriously considered and a more comprehensive approach to establishing the RDAs is now warranted for assessing nutrient intake to satisfy the known nutritional needs of practically all healthy people." He concludes by stating, "The RDAs should be more than just the avoidance of nutritional deficiency diseases. More emphasis on what nutrients are important for preventing diet-related disease and promoting optimal health should be considered."

How this relates to nutritional supplementation and trying to provide a more optimal level of intake of specific nutrients has been addressed by individuals such as Dr. Edward Schneider who is director of the National Institutes of Aging in Bethesda, Maryland. In his article on Recommended Dietary Allowances and the elderly (E.L. Schneider, E. M. Vining, E. C. Hadley, S. A. Farnham, "Recommended Dietary Allowances and the Health of the Elderly,"NEW ENGLAND JOURNAL OF MEDICINE, 314:157; 1/16/86) he advises that the RDA should be seriously reconsidered as it relates to nutrient need of the older-aged segment of our population to help promote disease resistance. Dr. Schneider points out we are a population of people who have vastly different nutritional needs depending on genetic uniqueness. He suggests that the RDAs are too constraining and do not properly reflect this array of biochemical uniqueness,

This point is most important as it relates to the demographic transition that is now occurring in the developed world. The post World War II baby boomers are now growing up to become mid-life individuals and soon to become older-aged individuals. Within the next twenty years, many more people will be in hospitals and institutions due to poor health associated with the aging process. Dr. Gio Gori, ex-director of the National Cancer Institute in the United States has pointed out that we must implement preventive nutrition now to help prevent the diseases of the aged not only to improve the quality of life of older-aged population, but also to reduce the tremendous cost and expenditures that come with hospitalization (G. B. Gori, B. J. Richter, "Macroeconomics of Disease Prevention in the United States," SCIENCE, 200:1124; June 1978).

Suboptimal nutrient intake results in suboptimal health which then increases the risk of many degenerative diseases. Early warning precursor markers of later-stage disease may be such things as fatigue, muscle weakness, insomnia, anxiety, reoccurring bad dreams, intestinal complaints of unknown origin and maybe even depression or other psychological or behavior changes. The work of Dr. Myron Brin has indicated that the early warning signs of suboptimal vitamin intake are these chronic health complaints, many of which may be psychological in origin. (M. Brin, "Erythrocyte as a Biopsy Tissue for Functional Evaluation of Thiamine Adequacy," JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION, 187:762; March 1964)

It is now recognized that there are a number of conditions or lifestyle habits which may further indicate the need for high levels of intake of specific nutrients. For example, Dr. Daphne Roe of Cornell University has found that female athletes have higher needs for vitamin B2 to promote optimal nutrition in women of the same age who are not heavy exercisers. In the absence of increased intake of vitamin B2, these athletic women may be suboptimally nourished and have more fatigue or poor recovery after exercise. (Daphne A. Roe, "Reply to Letter by Horwitt, " AMERICAN JOURNAL OF CLINICAL NUTRITION, 39/1:159-163; Jan. 1984)

Dr. Karl Folkers, an internationally known biochemist who has studied vitamin B6 for over forty years, has recently indicated that many of the muscle aches and pains associated with older age may be manifestations of suboptimal vitamin B6 intake. He considers suboptimal intake of B6 in the older age population to be equivalent to the 2 mg per day RDA. He suggests that a range of 25 to 50 mg per day of vitamin B6 would be considered an improvement in overall nutritional status which could result in improved physiological performance, (K. Folkers, "Perspectives from Research on Vitamins and Hormones," JOURNAL OF CHEMICAL EDUCATION, 61:747; 1984). Twenty-five milligrams a day is twelve-fold the RDA, but is certainly within the safe range of vitamin B6 intake. Therefore the benefit to risk ratio is far on the side of benefit.

Dr. Mark Levine at the National Institutes of Health has also spoken to the difference between adequate and optimal levels of vitamin C. He points out from a number of scientific studies he has conducted on vitamin C that the RDA level will certainly be enough to prevent scurvy, but may not provide the enhanced levels of immunological functioning that are found with increased intake of vitamin C (M. Levine, "New Concepts in the Biology and Biochemistry of Ascorbic Acid," NEW ENGLAND JOURNAL OF MEDICINE, 314:892; 1986),

Supporting the view that nutritional supplementation is valuable, the work of Dr. Worthington-Roberts and Breskin, involved surveying 900 dietitians in the state of Washington. They found nearly 60 percent of dietitians reported the personal use of nutritional supplements. The most commonly used supplements were multivitamins plus individual minerals and vitamins. (B. Worthington-Roberts , M. Breskin, "Supplementation Patterns of Washington State Dietitians," JOURNAL OF THE AMERICAN DIETETIC ASSOCIATION, 84:795; 1984). Although many registered dietitians may not recommend supplementation to their patients due to professional uncertainties, it is clear that they have chosen to utilize some nutritional supplementation for their own personal use. This suggests that they must have an intuitive or professional feeling that is of value.

Dr. Paul Saltman, a professor of nutrition at the University of California at San Diego, has recently commented in his best-selling book THE CALIFORNIA NUTRITION BOOK, that the daily use of a nutritional supplement containing vitamins and minerals may be a useful nutritional insurance policy. This same theme is mirrored in the article of Drs. Jensen and Briggs from the University of California at Berkeley. When talking about dietary supplements, they comment: "Perhaps the advice the Council on Scientific Affairs of the American Medical Association and other public health policy makers should be offering is that for the many people who cannot or do not select proper, well-balanced diets, a modest multivitamin/mineral supplement can be a safe nutritious and inexpensive part of a total health plan." (C. D. Jensen, G. M. Briggs, "Dietary Supplements" Letter, JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION, 258:909; 1987)

Dr. K. F. Gey has recently found that protection against ischemic heart disease and cancer seems to be afforded to those individuals with higher blood levels of anti-oxidant vitamins such as vitamin A, C, E and beta-carotene. Those individuals at higher risk to these diseases have normal RDA intake of the nutrients. (K. F. Gey, G. B. Brubacher, H. B. Stahelin, "Plasma Levels of Antioxidant Vitamins in Relation to Ischemic Heart Disease and Cancer, " AMERICAN JOURNAL OF CLINICAL NUTRITION, 45:1368; 1987) This would suggest that enhanced intake of "protector vitamins" beyond the RDAs may provide an optimal nutritional status and help defend against diseases of the aged.

As Dr. James Fries, professor of medicine at Stanford University Medical School, notes, "The protection against diseases of the aged is related to maintaining proper reserve of function in the major organ systems. The higher the level of reserve, the lower the biological age and the more resistant the individual is to disease." (J. F. Fries, "Aging, Natural Death, and the Compression of Morbidity," NEW ENGLAND JOURNAL OF MEDICINE, 303:130; July 1980) By maintaining optimal level of nutrient intake which may be greater than the RDA, improved organ reserve results which helps to resist underlying processes associated with degenerative disease.

Dr. Ovesen has recently pointed out that vitamin therapy in the absence of obvious deficiency may have manifold benefits. (L. Ovesen, "Vitamin Therapy in the Absence of Obvious Deficiency - What is the Evidence?," DRUGS, 27:148; 1984) He points out that evidence from controlled studies reveals a beneficial therapeutic effect of vitamin E in intermittent claudication in fibrocystic disease, vitamin C in pressure sores, suggestive value of vitamin C in the common cold, asthma and enhancement in athletic capacity, pantothenic acid in osteoarthritis, and folio acid in the prevention of neural tube defects.

Taken as a whole, the scientific literature of the middle 1980s indicates that there is a difference between adequate and optimal nutrition and that optimal nutrition may mean higher plasma levels of certain vitamins and mineral factors that help defend against the degenerative diseases of the aged. Although it is not accurate to say "if a little is good, a whole lot more ought to be better," it has became apparent that levels of intake of nutrients beyond the RDAs may be considered in many instances better than adequate and more suggestive of optimal.

In the following review of the opinions of many reputable scientific and medical investigators, the question concerning vitamin supplementation is reviewed. Their opinions reflect their own value system and the history they've had in their own research with enhanced levels of micronutrients and their impact upon physiological processes. This review is not considered to be exhaustive but rather exemplary of the kind of debate and supporting information that exists concerning the value of nutrient supplementation beyond that of the Recommended Dietary Allowance. The questions still remain as to what is the difference between adequate and optimal micronutrient intake and who "practically all healthy people" are.

For more information, please contact Dr. Farr by phone at (727) 461-7354 or by e-mail at chirodoc@becomehealthynow.com.

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