Sugar is under attack.

No, it's not the environmentalists this time. It's not the free-trade crowd. And it's not the South Florida Water Management District or the U.S. Army Corps of Engineers.The new foe is a best-selling diet book called "Sugar Busters!" It's raising anew all those nagging questions about the health effects of sugar - one of the nation's most lucrative agricultural products.

"Sugar Busters!" (Ballantine Books, $22) is a wildly popular tome that says a low-sugar diet will result in weight loss, reduced cholesterol, increased energy and "optimal wellness." The 270-page book follows in a long line of previous anti-sugar literature, and, like its predecessors, it thrives on many of the old beliefs about the evils of sugar.

Everyone knows sugar makes you fat, right? Everyone knows it contributes to diabetes, heart disease, premature aging and a host of other nasty medical conditions - not to mention that it makes your kids bounce off the walls. Right? Page 3 of "Sugar Busters!" boldly states, "Sugar is toxic!"

Some of these claims have become so ingrained in the American psyche that you can barely hear the faint pleas of the sugar industry: "It's not true! It's not true!"

While you'd expect the industry to protest, there is a growing consensus in the scientific community that sugar has been convicted unfairly again and again over the years - with "Sugar Busters!" being the most recent indictment.

"Sugar is always going to have a bad rap because it's a hot topic and people like to talk about how harmful it is," said Roger B. McDonald, a nutritionist at the University of California, Davis, who has studied the health effects of sugar. "But the fact is, sugar is no better or no worse than any other food. Everything is toxic if you eat too much of it."

Sugar does not cause diabetes - "that claim has been dead for over 40 years," McDonald said. And most scientists believe sugar does not cause obesity - except for the fact that people who eat too much of it tend to eat too much of everything else.

Also, there are no direct links between sugar and heart disease, premature aging, hyperactivity and many of the other ills that have been attributed to the second-most-maligned commodity in history - after tobacco, of course.

The sugar industry in Palm Beach County and South Florida - where a fourth of the nation's sugar supply is produced - has been slow to react to the negative publicity. For years, sugar farmers took a defensive posture, commenting only when criticized, if they commented at all. But that is changing.

In Washington, the Sugar Association trade group started financing scientific research in recent years, and it has begun to get the word out that sugar is not as bad as many people think.

"We would like sound science to drive opinions," said Barbara Miedema, a spokeswoman for the Belle Glade-based Sugar Cane Growers Cooperative, a member of the Sugar Association. "Facts need to rule the day."

The most recent association-sponsored study, released last year by Duke University Medical Center in North Carolina, found that "average, healthy people trying to lose weight do not necessarily have to restrict their sugar intake, as long as they lower the amount of fat and total number of calories they ingest daily."

By itself, one teaspoon of sugar contains just 16 calories.

The Duke study backed up a mantra that members of the nation's $21 billion sugar industry often repeat: "Sugar doesn't make you fat. Fat makes you fat."

Numerous government agencies have conducted their own research and determined that sugar causes no adverse health effects. Of course, those who consume sugar and don't take care of their teeth will get cavities.

The U.S. Health and Human Services Department, the U.S. Department of Agriculture and the Food and Drug Administration have issued reports in recent years stating that sugar consumption does not cause heart disease, diabetes, allergies, cancer, obesity or other health problems.

The government reports often rebutted anti-sugar studies of other organizations, many of them outside the traditional scientific research community.

"Most of the attacks on sugar are basically coming from wackos," said Judy Sanchez, a spokeswoman for Clewiston-based United States Sugar Corp., the largest raw sugar producer in the nation. "The medical community is not attacking us."

For instance, two recent reports out of the Netherlands and Italy have linked sugar with certain types of cancer. Those studies have never been replicated in the United States because, researches here say, the results are not credible.

The principal author of "Sugar Busters!" - 63-year-old H. Leighton Steward of New Orleans - readily admits that he, a businessman, and his three co-authors (medical doctors, not nutritionists) did no independent research to back up their conclusions. But he insists there is ample anecdotal evidence.

"Americans are getting fatter and fatter and more diabetic every year," Steward said in a recent interview from his vacation home in Wyoming. "And that's because our bodies were never designed to handle all this sugar we've been consuming."

Steward readily dismisses the arguments of the sugar industry and the scientific community. In his view, they are simply "defensive" reactions inspired by a "threatened" sector of the economy.