We knew that the trouble with fructose is how hard it hits our the liver and how much it raises our triglyceride levels, which increases our risks for heart attacks. High-fructose diets also lead us to secrete more insulin, which in turn leads to more insulin resistance.

Now we are learning that this deceptively low-glycemic sweetener can cause even more trouble. The trouble with fructose isn't just insulin resistance and heart attacks, as serious as they are. And it's not even just because of the massive amounts of high-fructose corn syrup that most people in the developed world added to their diets in the past 30 years or so.

The trouble is with fructose comes from even much smaller amounts. Even from the fructose in most fruit and in some vegetables.

I used to write off those relatively small amounts of fructose. Two years ago I argued here that what I considered the trivial amounts of fructose in food don't matter. The experts, like Dr. John Bantle, a professor of medicine in the division of endocrinology and diabetes at the University of Minnesota, told me so.

But we were overlooking research that shows that even these supposedly trivial amounts of fructose didn't matter. After all, the experts in the American medical establishment have been telling us for years that we need our daily servings.

The key study came out in an obscure professional journal six years ago. But I missed it until Dr. Michael Eades brought it to my attention. Dr. Eades, who with his wife Dr. Mary Dan Eades, wrote one of the low-carb bibles, Protein Power, as well as another half dozen books, also has one of the best wellness blogs, "Health & Nutrition."

His recent article, "Vegetarians AGE Faster," shows that vegetarians have significantly higher rates of advanced glycation end products (AGE) than do omnivores. It's not just a coincidence that the acronym for advanced glycation end products is AGE. As our bodies accumulate more and more glycated proteins, our bodies do grow older than our chronological years.

Glycated proteins in our bodies are simply proteins attached to sugars, but they don't work well there. I have tried to expose the problems with AGEs for years, and back in 2002 I first wrote about the trouble with AGEs for my "Diabetes Update" newsletter. More recently I wrote here about AGEs in May 2006, in June 2006, in September 2006, and in April 2007. But until now I failed to appreciate that natural fructose could be one of the devils in the AGE details.

The obscure study that Dr. Eades found finally convinced me that we need to limit not only high fructose corn syrup and other artificial fructose but also the naturally occurring fructose. My friend Joe Anderson has been arguing this case for years. But I thought that he was going too far.

He wasn't. I wasn't going far enough.

The researchers studied 19 vegetarian and 19 omnivore subjects recruited from the region around Bratislava, Slovak Republic. Three of the researchers worked at the Institute of Preventive and Clinical Medicine in Bratislava. One of them worked at the Institute of Physiological Chemistry of the University of Würzburg in Würzburg, Germany, where I happened to have studied for a year.