Ancel Keys, the Minnesota physiologist who put saturated fat on the map as a major cause of heart disease and was the first scientist to champion the health value of a Mediterranean-style diet, died on Saturday in Minneapolis. He was 100 and had remained intellectually active through his 97th year. His death was announced by the University of Minnesota, where he had long worked.

From humble beginnings -- he was born on Jan. 26, 1904, in Colorado Springs to teenagers who soon after moved to Berkeley, Calif., to find work -- Dr. Keys built a career that changed the thinking on many aspects of physiology and health, including the effects of starvation and the factors responsible for the most devastating epidemic in the industrialized world, coronary heart disease.

He was the founder in 1939 of what became a world-famous research facility, the Laboratory of Physiological Hygiene at the University of Minnesota School of Public Health, and he was its director for 33 years.

In the 1940's, a serendipitous event made his name known to millions. Because he had performed blood tests on himself in the Andes to determine the body's response to high altitudes, the War Department asked him to develop pocket-size food rations for World War II paratroopers. The result was the infamous K ration, named for its developer and distributed to hundreds of thousands of American troops during the war. Though complaints about the small nutrition-packed meals abounded, grateful recipients included 25 soldiers who were stranded for 10 days in a half-submerged transport plane in the South Pacific with nothing but 25 K rations and a gallon of water.