Sunday, June 12, 2011

98.6 Degrees Fahrenheit Ideal Temperature for Keeping Fungi Away and Food at Bay

The core or normal body temperature for a human being is 98.6 degrees Fahrenheit or 37 degrees Celsius. Body temperature based on an individual may vary but each person's core temperature remains fairly consistent. Metabolism rate fluctuates a human's body temperature. The slower the metabolic rate the lower the normal body temperature and the faster the metabolic rate the higher the normal body temperature. Our body temperatures are always lowest in the morning because of the long period of rest and of course the highest late at night from the day's activities and caloric intake.

Two researchers at Albert Einstein College of Medicine of Yeshiva University found that our 98.6° F (37° C) body temperature strikes a near perfect balance: warm enough to ward off fungal infection but not so hot that we need to eat nonstop throughout the day to maintain our metabolism. "One of the mysteries about humans and other advanced mammals has been why they are so hot compared with other animals," said study co-author Arturo Casadevall, M.D., Ph.D., professor and chair of microbiology & immunology at Einstein. "This study helps to explain why mammalian temperatures are all around 37° C." Dr. Casadevall also holds the Leo and Julia Forchheimer Chair in Microbiology and Immunology. Thousands of fungal species infect reptiles, amphibians and other cold-blooded animals. Mammals like ourselves are only infected by a few hundred from this fungal species. The warmer the core temperature, the harder it is for fungal species to thrive and therefore infect an animal or human. Dating back millions of years ago, this could be one of the reasons why mammals survived and dinosaurs didn't.

In this study, Dr. Casadevall and his Einstein coauthor, Aviv Bergman, Ph.D., professor and founding chair of systems & computational biology, devised a mathematical model that analyzed the benefits gained by body temperatures that protect against fungi versus the costs (in terms of extra food consumption) required to maintain body temperatures between 30° and 40° C. The optimal temperature for maximizing benefits while minimizing costs was found to be 36.7° C, which closely approximates normal body temperature (98.06° F).

Being able to protect yourself or at least be less susceptible to fungal infections carries with it a lot of benefits. Some fungi can cause serious diseases in humans, several of which may be fatal if untreated. These include aspergilloses, candidoses, coccidioidomycosis, histoplasmosis and mycetomas. Other fungi can attack your eyes, nails, hair. Some fungi infections that you may be sound familiar are ringworm and athlete's foot which are skin infections.

"This study is a good example of how mammalian evolution has been driven by both external biological factors and internal physiological constraints," said Dr. Bergman.


A. Bergman, A. Casadevall. Mammalian Endothermy Optimally Restricts Fungi and Metabolic Costs. mBio, 2010; 1 (5): e00212-10 DOI: 10.1128/mBio.00212-10

Cook GC; Zumla AI (2008). Manson's Tropical Diseases: Expert Consult. Saunders Ltd. p. 347.

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