Dietary supplements of the metal chromium can extend the life span of rats by more than one-third and may have similar effects in humans, a Minnesota researcher said yesterday.
Biochemist Gary W. Evans of Bemidji State University in Minnesota gave a special chromium supplement to 10 rats and compared them to 20 rats that received chromium in a form less readily absorbed. After 41 months, he reported yesterday at a San Francisco meeting of the American Aging Association, 80 percent of the rats that received chromium picolinate were still alive, while all the others were dead. The rats getting the supplements lived an average of one year longer.
"That's a real departure from the usual life expectancy patterns," said gerontologist Caleb E. Finch of the University of Southern California. Mr. Evans seems to have found "a new and unexpected potential variable in life span that deserves serious consideration in longer-lived species," Mr. Finch said.
Previous research has found that the only factor that could produce substantial increases in life span in animals is a significant reduction in caloric intake. But the chromium supplements can produce an equally large increase without any such restrictions, Mr. Evans said.
More than 90 percent of U.S. adults have a dietary deficiency of chromium, in part because it is not readily absorbed from many foods, according to biochemist Richard Anderson of the U.S. Department of Agriculture in Beltsville, Md. USDA researchers have developed and patented a form of chromium, called chromium picolinate, that is more easily absorbed by the body. That is the form used by Mr. Evans.
"This could potentially be a major finding," said Mr. Anderson, "but whether it is reproducible remains to be established . . . There's no reason not to believe it, however."
Because chromium has other beneficial effects as well, Mr. Evans said that he would "very definitely suggest that people take a multivita
min-multimineral supplement containing chromium picolinate" on a regular basis.
Researchers have been searching for centuries for a magic elixir that would extend human life span. They have found no such elixir, but 60 years ago researchers observed that rats fed a diet containing only 60 to 65 percent of their normal caloric intake lives as much as 50 percent longer.
Over ensuing decades, researchers have observed similar results in other species ranging from one-celled protozoa to fish and perhaps even to primates. One proponent of the theory, University of California pathologist Roy L. Walford, has nearly doubled the life span of laboratory mice.
Physiologist Edward Masoro of the University of Texas Health Sciences Center in San Antonio has argued that restricted calorie intake works because it reduces the amount of the sugar glucose circulating in the animals' bloodstreams -- a theory that is now becoming widely accepted.