CHICAGO, May 25 (Reuters) - If men ever needed a reason to justify that extra cup of coffee, here it is: four or more cups of coffee a day appear to reduce the risk of gout, Canadian researchers said on Friday.

Gout is a painful joint disorder caused by a buildup of uric acid in the blood. It affects about 6 million people in the United States, and tends to be a bigger problem for men than women.

In the past, patients at risk for gout were advised to avoid coffee, but Dr. Hyon Choi of the University of British Columbia in Vancouver, Canada, and colleagues at Harvard Medical School in Boston wanted to see just what effect coffee might have on the condition.

Choi and colleagues analyzed data from a U.S. health and nutrition survey between 1988 and 1994.

The study is based on a survey of about 50,000 men aged 40 to 75 with no history of gout. They filled out detailed questionnaires about dietary habits, including what they drank.

Over the 12 years of the study, during which 757 men developed gout, the risk was lower for those who drank more coffee, Choi reported in the journal Arthritis & Rheumatism.

"We found that when they are drinking four to five cups of coffee, there was a 40-percent reduction. Drinking six or more cups resulted in a 50- to 60-percent reduction (in the risk for gout)," Choi said in a telephone interview.

Men who drank decaffeinated coffee also benefited, Choi said, but tea appeared to have no effect.

The researchers found significantly lower levels of uric acid in the blood of those who consumed large quantities of coffee. Uric acid is the compound that causes gout.

Choi said the findings appear to suggest that something in the coffee other than caffeine -- such as a strong antioxidant -- may be helping to reduce uric acid levels.

Coffee is one of the most widely consumed beverages in the world. More than half of Americans drink about two cups a day.

Choi said people should not rush out to the corner coffee shop to treat their gout.

But "if you are drinking coffee already and have gout or are at higher risk of developing gout ... there is no need to reduce or stop coffee consumption," he said.