Longevity studies find ‘cool’ mice have edge

Q: Does a lower body temperature mean a longer life?

A: Some studies show a correlation between lower body temperatures and greater longevity, although there is no proof of a cause-and-effect relationship in humans.

The first such major study in warmblooded animals, reported in the journal Science in 2006, was an experiment involving mice at the Scripps Research Institute.

Genetically engineered mice with extra-sensitive temperature control switches in the hypothalamus were raised with core body temperatures just a fraction of a degree cooler than those of their litter mates; caloric intake was the same. The researchers found the median life span was 12 percent greater in the cooler males, 20 percent greater in the females.

As for humans, not enough research has been done to establish persuasive evidence that being colder helps people live to be older. But some research suggests that being older inclines people to be colder.

For instance, a large study published in 2011 in The Journals of Gerontology compared the ages and body temperatures of 18,630 people from 20 to 98 years old who had oral temperature readings as part of a standardized health appraisal at a health maintenance organization. It found that women, in general, tended to be cooler than men. Also, mean temperature decreased with age, with a difference of 0.3 degree Fahrenheit between the oldest and youngest groups, even after controlling for sex, body mass index and white-blood-cell count.

Also, this study found that mean body temperature of the population overall was 97.3 degrees. Researchers Jill Waalen and Joel N. Buxbaum wrote, “This observation is consistent with other studies in a variety of populations that have found that normal body temperature defined as the population mean is lower than the long-standing accepted norm of 98.6 degrees F.” Celia Storey added information to this report.