One of the newer entrants to the burgeoning sports-nutrition market, caffeinated gum promises to deliver a faster burst of energy than other ergogenic aids because it doesn't have to pass through the digestive system.

"Caffeine is a well-studied performance enhancer," said Kristina LaRue, a registered dietitian specializing in sports nutrition.

But much of the boost might be psychological, said Carl Paton, an associate professor at New Zealand's Eastern Institute of Technology, who has conducted three studies on caffeinated gum.

"Caffeine has the benefit of reducing the perception of fatigue, so you can potentially run harder with it in your system," he said.

Until 2004 the World Anti Doping Agency placed limits on caffeine intake, but it is so ubiquitous that the limit was dropped. But that doesn't mean that everyone is on board with the use of caffeine.

A recent study in the Journal of Sports Medicine revealed that those who consume large amounts of caffeine develop a tolerance to it. Someone who drinks an average of only one cup of coffee a day might get a lift from caffeine gum, but the magnitude of the boost drops as the average coffee consumption increases.

Paton said that it is essential to keep in mind that the impact of caffeine is highly individualized.

Washington Post

Claims of DNA age testing are disputed by naysayers

A new $89 test claims to calculate the age of the DNA in your cells and tell you how well you are aging. But critics of the test are skeptical.

The test, called TeloYears, measures the length of telomeres, the caps that cover the ends of chromosomes. Companies selling telomere tests say that studies show shortened telomeres are a risk factor for illness.

But critics say that what the tests tell us about the life span of a cell may not translate to the life span of an individual. As a result, they argue, it's too soon to make sense of these results.

Telomeres are often described as the biological equivalent of the plastic caps at the ends of shoestrings that prevent threads from fraying.

As we age, our telomeres shorten. That's because every time a cell divides and DNA replicates, a chunk of telomere disappears.

But how that correlates to how long someone lives is up for debate. The length of telomeres varies widely among people in the same age group, researchers report. They are yet to be convinced that there's a correlation between the length of telomeres and the length of life.

Dallas Morning News