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Biographical Article

Walter Mertz (1923–2002)¹

² Retired, Beltsville Human Nutrition Research Center, USDA, Beltsville, MD 20705-2350 and ³ Departments of Preventive Medicine and Community Health and Anesthesiology, The University of Texas Medical Branch, Galveston, TX 77555-1109

^* To whom correspondence should be addressed. E-mail: zincdr{at}aol.com.

Walter Mertz was a scientist whose research advanced our knowledge of the metabolic aspects of trace elements. He was a leading international authority on human nutrition and, as a member of numerous national and international committees, he contributed to nutrition recommendations. He was a fellow of the AIN and after his retirement was inducted into the USDA Agricultural Research Division's Hall of Fame "for contributions and leadership in elucidating the importance to health of several trace elements and promoting research on dietary risk factors for chronic disease."

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	Early Years

TOP Early Years NIH Years Walter Reed Years Beltsville Years Contributions to Advancing... Awards and Retirement/Later... LITERATURE CITED

	NIH Years

TOP Early Years NIH Years Walter Reed Years Beltsville Years Contributions to Advancing... Awards and Retirement/Later... LITERATURE CITED

 
Fortunately, Dr. Mertz received an award from the U.S. Brewers' Yeast Council to be a Research Fellow at the National Institute of Arthritis and Metabolic Diseases, NIH, Bethesda, MD. Thus, in October 1953, 6 weeks following their wedding, he departed for America with the hope to be reunited with his wife in the near future. Unfortunately, her voyage to the U.S. was delayed, because she could not obtain a visa in the Saar region, a protectorate of France after WWII with its own government and constitution. The confusion concerned whether the Germans or the French were responsible for issuing her travel documents. In December 1954, Dr. Mertz returned to France to take matters in his own hands and personally went to meet the U.S. Consul in Paris. He declared that he would not return to the U.S. without his wife, because they had been separated for more than one year. The visa was finally granted after 10 days; triumphantly, they sailed together to the U.S. on the Queen Elizabeth, the same ship that transported him to America as a prisoner 13 years earlier.

Dr. Mertz's tenure at NIH (1953–1961) was the beginning of a long, successful, and productive research career. He worked with Dr. Klaus Schwarz whom he first met at the University of Mainz in 1948. Upon the invitation of Floyd Daft, Director of the National Institute of Arthritis and Metabolic Diseases (now NIDDK), Dr. Schwarz had begun work at NIH in 1949. Soon after arriving, Dr. Mertz met the director of NIH, the eminent nutritionist, W. Henry Sebrell Jr, who said to him "Go out there and make a difference." Dr. Mertz took Dr. Sebrell's admonition seriously.

Schwarz and Mertz focused on the nutritional aspects of liver disease. Vitamin E- and sulfur-containing amino acids were already known to prevent liver necrosis induced by a Torula yeast-based diet, but a third component, Factor 3, was also protective. This factor had been isolated from pig liver and had the aroma of garlic. In 1957, Schwarz and Foltz reported that the active ingredient of Factor 3 is selenium. This discovery prompted research regarding its biochemistry that ultimately clarified the nutritional essentiality of selenium.

Schwarz and Mertz found that the above diet also impaired glucose uptake and that Factor 3 was not protective, but another factor, which they named glucose tolerance factor, was (1). They found that brewers' yeast and pork kidney prevented the condition. In 1959, they identified glucose tolerance factor as an organic compound containing trivalent chromium and demonstrated the effect of chromium (III) complexes on glucose uptake by fat tissues (2,3).

	Walter Reed Years

TOP Early Years NIH Years Walter Reed Years Beltsville Years Contributions to Advancing... Awards and Retirement/Later... LITERATURE CITED

 
From 1961 to 1969, Dr. Mertz was Head of the Department of Biological Chemistry at the Walter Reed Army Institute of Research (Washington, DC) where he and his colleagues showed that chromium nutriture affects glucose metabolism in humans (4). His studies were the first to show that chromium (III) is an essential nutrient for humans and that it potentiates the action of insulin in glucose uptake. This seminal work opened an entire new field of research that is being actively pursued even today with the goal to identify the molecular actions of chromium (III) compounds. At that time, which coincided with the race to land humans on the moon, Dr. Mertz also participated with NASA in metabolic studies of humans exposed to gravity in centrifuges and in formulating dietary recommendations for astronauts.

	Beltsville Years

TOP Early Years NIH Years Walter Reed Years Beltsville Years Contributions to Advancing... Awards and Retirement/Later... LITERATURE CITED

 
In 1969, Dr. Mertz was appointed Chief of the Vitamin and Mineral Nutrition Laboratory of the Human Nutrition Research Division, Agricultural Research Service, USDA. He became the first director of the newly formed Nutrition Institute, later renamed Beltsville Human Nutrition Research Center (BHNRC), Beltsville, MD, and served in this capacity for 21 years. The initial core laboratories were: Vitamin and Mineral, Protein, Lipid, and Carbohydrate. Later, Dr. Mertz added the Human Studies Facility and Food Composition Laboratory. He and his colleagues continued work that further described the role of chromium in human nutrition and advanced the BHNRC to one of the leading research institutions in the world in trace element research (5,6). He also directed research concerning discrepancies between reported energy intakes in dietary histories and actual energy intakes and on many other topics regarding the role of nutritionally essential trace elements. During Dr. Mertz's tenure as director of the BHNRC, scientists from all over the world sought an opportunity to come to Beltsville for the latest training in analytical techniques and/or to learn how to organize and execute large human studies. At Beltsville, they experienced a congenial atmosphere, a condition that Walter Mertz deemed a prerequisite for creative research. Numerous others would visit informally to obtain advice from the director who had an open door policy.

	Contributions to Advancing Nutritional Sciences

TOP Early Years NIH Years Walter Reed Years Beltsville Years Contributions to Advancing... Awards and Retirement/Later... LITERATURE CITED

 
Prior to his retirement as director of the BHNRC on December 15, 1992, Dr. Mertz presented a farewell address entitled "A Century of Human Nutrition Research and Beyond." It was recorded by C-SPAN and televised three times. Excerpts are given here because they describe his personality and remarkable vision and, retrospectively, the impact of his teachings. He was introduced by Dr. K. Darwin Murrell, Director of USDA's Beltsville Agricultural Research Center who indicated that a noted nutritionist confided to him that Dr. Mertz was "One, if not the most important research scientist in the field of trace minerals and vitamins, worldwide." Dr. Mertz began his lecture by stating that 40 years ago, as a junior resident in surgery, the three major surgeries then were appendectomy, thyroidectomy, and surgical removal of cancers. Now, the first two surgeries are somewhat rare. Specifically, removal of the appendix is relatively rare due to a better diet higher in fiber. Goiter, which can result in Cretinism, was a major problem in southern Germany when he was born but now has been nearly eradicated due to the iodinization of salt. For cancer, a strong nutritional association is presently recognized. As a result, an emphasis is now on dietary prevention of cancer, with some success.

Dr. Mertz then showed his favorite slide, based on Bertrand's law, that every essential nutrient is potentially also a poison if ingested in excess or can cause death if deficient in the diet. He stated that it would be "unscientific" to recommend a single number for daily intake because a range of intake can support life, not a single value.

After providing a historic perspective on the discoveries of macronutrients and micronutrients (vitamins and trace elements) in the 19th and 20th centuries, he addressed the Future Challenges of Nutrition Research. As the first challenge, he envisioned the importance of identifying the genes that determine our life-long nutritional status and indeed our general health, giving hypercholesterolemia as an example. From a practical point of view, we need to identify the 15–20% of the population who are salt-sensitive in order to reduce hypertension in these populations. The practical aspects of using a genomic profile (an area now called nutrigenomics) to identify individuals at high risk for specific deficiencies or chronic health conditions would be obviating the need to treat the entire population as a preventive measure.

As the second challenge, Dr. Mertz saw an understanding of the relation of nutrition and longevity, an area that he predicted will receive increased research attention in the future. He noted that it has been demonstrated in animals "many, many times" that longevity can be increased by decreasing caloric intake by one-third to one-half. The third challenge that he addressed gains specific significance in terms of the present state of nutrition science: we need to do a better job of interacting with the public, who are influenced by too many "non-scientific" sources or poorly proven facts. We must stress, "There are no easy cures for anything." As professional nutritionists, we should promote a greater daily consumption of a variety of whole foods.

In summary, he recommended: 1) the daily diet should be balanced including many different sources (variety) of foods to increase the chances of adequate but not excessive nutrient intake; 2) food/caloric intake level should be in moderation; 3) meals should be prepared and presented in an appetizing manner; and 4) most importantly, mealtime should be a time of enjoyment.

His remarks about the ambience of eating reflect Dr. Mertz's joie de vivre that pervaded all aspects of his life, not only his fondness of good food, but also his love, incredible enthusiasm, and devotion for science, philosophy, poetry, and music. He was convivial and an aficionado of beers. Forrest H. "Frosty" Nielsen of the Grand Forks Human Nutrition Center (USDA) relates that at the 3rd TEMA Symposium in Weihenstephan, Germany in 1977, he has "fond memories of Walter at the podium with a large mug of beer in one hand, leading drinking songs with the other, and decorated with a necklace of sausages draped around his neck"!

For more than thirty years, from 1968 to 2000, Dr. Mertz served on numerous committees of the National Academy of Sciences, including three terms as member of the Food and Nutrition Board. He is coauthor of three editions of the Recommended Dietary Allowances (8th–10th) and of the National Academy of Sciences' seminal publication, "Diet, Nutrition and Cancer." He was a Senior Editorial Advisor for the Surgeon General's Report on Nutrition and Health (1988). Dr. Mertz was a member of a joint FAO/IAEA/WHO Expert Consultation group that published "Trace Elements in Human Nutrition and Health" (1996). He also contributed to the WHO publication, "Vitamin and Mineral Requirements in Human Nutrition" (2004).

Dr. Mertz's research and administrative abilities made major and immeasurable contributions toward advancing the field of nutrition as well as promoting policy that continues to improve human health around the world. Indeed, his generosity and unselfishness gained the respect of nutritional scientists globally, including those in countries behind the Iron Curtain. He was elated when the Iron Curtain came down and he kept a piece of the Berlin wall on his desk. Not only did he administratively help some of the foreign scientists to attend meetings in the U.S., but he assisted them financially with personal funds.

	Awards and Retirement/Later Years

TOP Early Years NIH Years Walter Reed Years Beltsville Years Contributions to Advancing... Awards and Retirement/Later... LITERATURE CITED

 
Dr. Mertz was primarily interested in advancing the international standing of the BHNRC. He was not one to seek recognition or to promote himself. Even so, he was the recipient of numerous awards, including the AIN Osborne and Mendel Award (1971) for "outstanding recent basic research in nutrition," and the Lederle Award (1982) for his "recent investigative contributions to the basic understanding of human nutrition." While at Walter Reed, he received the Department of the Army's Research and Development Achievement Award in 1969. At the USDA, he received two Service Awards, Superior in 1972 and Distinguished in 1988. The agency recognized his dynamic leadership as evidenced by expanded international recognition of BHNRC as a center of scientific excellence and exceptional productivity of leading edge basic research concerning nutrition and its application to humans. In 1986, Dr. Mertz received the Certificate of Merit Service to Agriculture Award from the National Honor Society of Agriculture, Gamma Sigma Delta, of the University of Maryland. The citation read, in part: "Dr. Mertz may very well be the world's most prominent scientist investigating the importance of trace elements in human nutrition. He has, unquestionably, provided the strongest scientific leadership in the trace element field in the United States during the past 20 years." A prestigious "International Award for Modern Nutrition" was bestowed on him in 1987 in a ceremony at Brig, Switzerland, for his extended efforts via WHO/United Nations to improve the nutritional status of people throughout the world.

While he published 200 papers, including several important reviews following his retirement (7–10), his contributions went far beyond scientific publications. His influence on nutritional policy as a leader of national and international organizations such as the National Academy of Sciences and the WHO to improve health via good nutrition was monumental. Walter Mertz was keenly aware of the important role played by dietitians regarding disseminating nutritional information. In his later years, he recognized the need to bring together nutritionists and toxicologists to discuss the sometimes conflicting views about the beneficial and adverse effects of trace elements.

For those of us who had the privilege to work with him, we sorely miss him. He was our admired mentor, a gentleman in the true sense, involving all aspects of his life, friend and confidant, who enjoyed life and could generate a congenial atmosphere around him even during those scientific discussions in which different views prevailed and tensions arose. He practiced strict scientific integrity with the highest ethical standards. Contrary to the obituary published in the Washington Post on July 2, 2002, Dr. Mertz received no patents or remunerations for any chromium compounds or for any of his discoveries. His integrity earned the respect of peers throughout the world.

Perhaps Dr. Mertz's greatest gift to science and humanity was his mentoring many scientists who carry on the search for, and application of, knowledge and understanding of nutrition and related topics. For his belief in the need to foster an environment conducive to creativity, he loved to cite the anecdote of the Greek teacher Diogenes: when Alexander the Great came to see Diogenes, who was basking in the sun, he offered: "Ask any favor you choose of me." Whereupon Diogenes retorted: "Cease to shade me from the sun."

He was fortunate in his personal life to be an accomplished musician and a talented classical pianist. He was an avid and life-long learner, always interested in the latest technology. With his wife, Marianne, he was a passionate gardener, specializing in roses. Unfortunately, the deer population around their home enjoyed them also. He was fluent in at least four languages, in addition to a proficiency in reading Latin.

Walter Mertz died of lung cancer on June 28, 2002 at his home in Rockville, Maryland. On July 3, 2002, all ARS facilities throughout the United States flew the flag at half staff in honor of him. His beloved wife of 49 years, Dr. Marianne Mertz, survives him at their home in Rockville, Maryland.

	ACKNOWLEDGMENTS

 
We thank Harold H. Sandstead, Professor Emeritus, Department of Preventive Medicine and Community Health, The University of Texas Medical Branch; Orville A. Levander, retired, research chemist, BHNRC; Forrest H. Nielsen, Research Nutritionist, USDA Grand Forks Human Nutrition Center; John G. Bieri, Scientist Emeritus, NIH; Gerald F. Combs Sr, Adjunct Professor, University of Southern Mississippi; and Michael Hambidge, Professor, Department of Pediatrics, University Colorado Health Science Center for critical reading of the manuscript and for sharing their reminiscences.

	FOOTNOTES

 
¹ Author disclosures: J. C. Smith Jr, no conflicts of interest; W. Maret is the nephew of Walter Mertz.

Manuscript received 12 October 2007.

	LITERATURE CITED

TOP Early Years NIH Years Walter Reed Years Beltsville Years Contributions to Advancing... Awards and Retirement/Later... LITERATURE CITED

 

1. Schwarz K, Mertz W. A glucose tolerance factor and its differentiation from factor 3. Arch Biochem Biophys. 1957;72:515–8.[Medline]

2. Schwarz K, Mertz W. Chromium (III) and the glucose tolerance factor. Arch Biochem Biophys. 1959;85:292–5.[Medline]

3. Mertz W, Roginski EE, Schwarz K. Effect of trivalent chromium complexes on glucose uptake by epididymal fat tissue of rats. J Biol Chem. 1961;236:318–22.[Free Full Text]

4. Glinsmann WH, Feldman FJ, Mertz W. Plasma chromium after glucose administration. Science. 1966;152:1243–5.[Abstract/Free Full Text]

5. Mertz W. Chromium occurrence and function in biological systems. Physiol Rev. 1969;49:163–239.[Free Full Text]

6. Smith JC Jr. Methods of trace element research. In: Mertz W, ed. Trace elements in human and animal nutrition. 5th ed, 1st vol. New York: Academic Press; 1987. p. 21–56.

7. Mertz W. Chromium in human nutrition. J Nutr. 1993;123:626–33.[Abstract/Free Full Text]

8. Mertz W. Essential trace metals: new definitions based on new paradigms. Nutr Rev. 1993;51:287–95.[Medline]

9. Mertz W. Risk assessment of essential trace elements: new approaches to setting recommended dietary allowances and safety limits. Nutr Rev. 1995;53:179–85.[Medline]

10. Mertz W. Three decades of dietary recommendations. Nutr Rev. 2000;58:324–31.[Medline]

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