But he disputed Dr. Kummerow’s contention that saturated fats are benign and that polyunsaturated vegetable oils promote heart disease. “There are studies that clearly show a substitution of saturated fats with polyunsaturated fats leads to a reduction in cardiovascular disease,” said Dr. Eckel, a professor at the University of Colorado.

Robert L. Collette, the president of the Institute of Shortening and Edible Oils, a trade association, says oil manufacturers work with their customers to take precautions against oxidation.

“Oxidation is something that consumers can detect,” he said. “Therefore, it is in everyone’s best interest to control it.”

The long arc of Fred Kummerow’s life and career illustrates the frustratingly slow pace of science and the ways in which scientific conformity can hinder the search for answers. Born in Germany just after World War I broke out, he moved to Milwaukee with his family when he was 9. His father, who worked at a cement block factory, did not have the money to send him to college, so Dr. Kummerow worked full time at a drug distribution company while attending the University of Wisconsin in the evenings. After he earned a Ph.D. in biochemistry, his first job was at Clemson University in South Carolina, where he helped prevent thousands of deaths in the South from pellagra, a disease resulting from a deficiency of vitamin B3.

His early research on trans fats was “resoundingly criticized and dismissed,” said Dr. Walter Willett, the chairman of the nutrition department at the Harvard School of Public Health, who credited Dr. Kummerow with prompting his desire to include trans fats in the Nurses’ Health Study. A 1993 finding from that study, which showed a direct link between the consumption of foods containing trans fats and heart disease in women, was a turning point in scientific and medical thinking about trans fats.

“He had great difficulty getting funding because the heart disease prevention world strongly resisted the idea that trans fats were the problem,” Dr. Willett continued. “In their view, saturated fats were the big culprit in heart disease. Anything else was a distraction from that.”

At an age when life itself is an accomplishment, Dr. Kummerow said he had no intention of stepping away from the work that has consumed him for six decades. He continues to work from home and talks daily to the two scientists who work in his lab, which receives funding from the Weston A. Price Foundation.