In excessive amounts . . .  for rats.  The Washington Post reports on a recent study showing that

Sugar, even at moderate levels, could be toxic to your health — or at least to your sex life.  Scientists at the University of Utah looked at how sugar affected mice and found that the mouse equivalent of just three sugary sodas a day had significant negative effects on life span and competition for mates.

“That’s three sodas if the rest of your diet is pristine and sugar-free,” said lead author and biologist James S. Ruff. “And those are 12-ounce sodas, not double Big Gulps.”  Sugar-fed females died twice as quickly as control mice, which were fed the same total number of calories. While the sugar-fed males did not die more quickly, they had trouble competing against the control males for mates and were less likely to hold territory and reproduce.  For the rodents on the sweetened diet, sugar accounted for 25 percent of their total calorie intake. Up to a quarter of Americans consume that proportion of sugar as part of their diets.

Of course, humans are not rats.  But according to the study’s author, biologist Wayne Potts,

About 80 percent of substances that are toxic in mice are toxic for people as well . .  so it is likely that the effects of extra sugar could be similar in humans.

I remember first finding the sugar jar as a child.  It was a revelation to discover the essence and source of something so good.  I don’t take away from this study that we need to stop enjoying birthday cakes or pies at Thanksgiving.  Rather, sugar, like alcohol and so many of life’s pleasures must be enjoyed prudently.