"When you give fructose to animals, they absolutely develop every feature of metabolic syndrome: they get abdominal fat, high triglycerides, low HDL, their blood pressure goes up and they get insulin resistance," Johnson said. "However, you must give massive amounts of fructose to rats to raise uric acid levels, because rats and most other animals have an enzyme that breaks down uric acid. Humans lack that enzyme. It turns out humans get gout but other animals don't."

If you inhibit the enzyme in rats that breaks down uric acid, it takes only a small amount of fructose to cause uric acid to rise and the symptoms of metabolic syndrome to appear in the animals, he said.

Abstract P237

Timing of fructose intake affects weight gain, blood pressure and behavior

Researchers found that abnormalities in blood pressure and weight gain were linked to the timing of the availability of fructose, a dietary sugar, in a study conducted in mice. When sugary liquids were consumed during the day (the usual sleeping period for mice), mice showed greater weight gain and a reversal in blood pressure rhythms.

Researchers implanted small ambulatory monitors to measure blood pressure around the clock in mice. Mice were given either continuous access to fructose water (10 percent) or restricted access for 12 hours during the day (light) or 12 hours at night (dark).

"The first thing we noticed was that the mice on restricted access rushed to their drinking bottles to load up on the sweetened beverage, similar to teenagers who drink too many soft drinks," said Mariana Morris, Ph.D., study co-author and vice president for graduate studies and chair of the Pharmacology and Toxicology Department, in the Boonshoft School of Medicine at Wright State University in Dayton, Ohio.

Researchers reported that groups consuming fructose continuously or during the dark period, showed an increase in blood pressure with a characteristic spike during the night when mice are usually active. However, in mice that consumed fructose during the day, the blood pressure pattern was reversed, high in the day and low in night. The blood pressure change was also associated with higher stress hormone levels.

"The reversal in the day/night rhythm is similar to the pattern seen in human diabetics, suggesting the timing of fructose intake may be important in cardiovascular pathologies," Morris said.

Researchers also observed increased weight gain in mice given fructose during the light period. This weight gain occurred even though total calorie consumption (fructose water and solid food) was similar.

"This model may be similar to the human condition of night time binging of fructose laden foods and beverages," Morris said. "The results indicate that consideration must be given not only to the amount of calories consumed but also the timing of intake."

Source: americanheart