Eating less red meat and seafood while consuming more low-fat dairy products cuts the risk of developing the painful joint condition gout by about half, according to researchers who studied the diets of thousands of men.
Eating lots of vegetables and fruit, shunning alcohol use and maintaining a normal body weight also significantly reduced the chances of getting gout, the most common form of inflammatory arthritis in men.
"Every single seafood type we looked at was associated with increased risk of gout," said Dr. Hyon K. Choi, a rheumatologist at Massachusetts General Hospital in Boston.
"This is the first evidence that dairy products can be strongly protective," he added, and the first confirmation that gout can be triggered by foods rich in a substance called purine that's often associated with high protein levels.
Gout affects about 3.4 million American men, causing sometimes-excruciating episodes of pain in feet and joints, but is less common in women, occurring only after menopause.
The link between gout and rich foods and alcohol has been conventional wisdom for centuries, leading to its reputation as a disease of middle-aged rich man. Famous sufferers included Charlemagne, Henry VIII, Benjamin Franklin and Leonardo da Vinci.
Researchers at Massachusetts General, Brigham and Women's Hospital and Harvard's medical and public health schools followed 47,150 men with no history of gout for 12 years to pinpoint exactly how diet contributes to gout. The men were part of a long-running health study of doctors and male health professionals.
They were questioned periodically about how much of 130 foods and beverages they consumed the previous year, and about their weight, medication use and medical conditions. When the study ended in 1998, new cases of gout had been documented in 730 men, or nearly 2 percent.
The study was reported in Thursday's edition of the New England Journal of Medicine.
"This study says diet may be one of the most effective means of actually preventing (and controlling) gout," said Dr. John Klippel, president of the Arthritis Foundation. "People have become rather cavalier" about diet.
Purine is a compound in the genetic material in each cell, but the amount inside cells varies from food to food. Digestion breaks purine down into uric acid.
Gout is caused by too much uric acid in the blood. The excess uric acid forms crystal deposits in joints, particularly in the big toe, feet and ankles.
The men's protein intake and other data were used to estimate purine levels in their diet. The men were divided into five groups, from those with the lowest consumption of each food up to the highest.
Gout was 51 percent more likely to develop in the group with the highest seafood consumption, and 41 percent more likely in the group with the highest consumption of beef, pork and lamb. The group with the highest consumption of low-fat dairy products was 42 percent less likely to develop gout.
There was no association between gout and high intake of high-fat dairy products or vegetables rich in purine, including peas, beans, mushrooms, cauliflower and spinach. The researchers said further study is needed to see if people who already have gout could prevent attacks with a low-purine diet.
Dr. Manuela Pedra Nobre, a rheumatologist at University of Medicine and Dentistry of New Jersey in Newark, said the results confirm what she tells her patients to prevent further gout attacks - to avoid high-protein meat and seafood, particularly lobster and shrimp.
On the Net:
New England Journal of Medicine: http://www.nejm.org
Arthritis Foundation: http://www.arthritis.org