Walter Mertz, 79; Discovered a Key to Insulin’s Efficacy

Walter Mertz, a government nutrition researcher who was one of the first to report that chromium is essential as a trace element needed to make insulin work effectively, has died. He was 79.

Mertz died of cancer June 28 at his Rockville, Md., home.

He researched vitamins and minerals for the U.S. Department of Agriculture for 21 years, retiring in 1993 as director of the Human Nutrition Research Center of the Agricultural Research Service. He conducted his early research at the National Institutes of Health and the Walter Reed Army Institute of Research.

Mertz edited the authoritative text “Trace Elements in Human and Animal Nutrition.” He was co-author of three editions of the government’s Recommended Dietary Allowances and the National Academy of Science publication “Diet, Nutrition and Cancer,” one of the first reports to associate diet with human cancers.

His early chromium research was performed at NIH, where in 1957, he and Kenneth Schwartz isolated a compound, extracted from pork kidney, that they called glucose tolerance factor. Two years later, chromium was identified as the active component of glucose tolerance factor. The compound binds insulin to cell membranes and helps regulate blood sugar metabolism.

As an authority on human nutrition, Mertz was advisor to the World Health Organization and chairman of the committee that issued recommendations for trace element nutrition.

Mertz graduated from the University of Mainz and its medical school in his native Germany. He joined the NIH as a research fellow in 1953 and was chief of the biological chemistry department of the Army institute in the 1960s. He was named chief of the USDA’s vitamin and mineral nutrition laboratory in 1969. He is survived by his wife, Marianne.