The study of 22,000 adults, including 517 with diabetes, also found those with the disease who ate less than one serving of fish per week were about four times more likely to have protein in their urine than those who ate at least two servings of fish per week.

Study co-author Dr. Amanda Adler of the Medical Research Council epidemiology unit at Addenbrooke's Hospital in Cambridge, England, said protein in the urine is one of the earliest signs of kidney disease.

Adler and colleagues suggest one possibility is that the "unique nutrient composition of fish" may benefit kidney function by enhancing blood glucose control and improving plasma lipid profiles. Or, they said, people who consume fish may have other lifestyle factors that reduce their risk of having protein in the urine.

In addition to eating fish, people can reduce the risk of albuminuria -- protein in the urine -- by controlling glucose, lowering blood pressure, smoking cessation and following a diabetic diet as prescribed by a doctor, HealthDay News reported.

The study was published in the American Journal of Kidney Diseases.