Including fish in your diet twice a week may prevent kidney damage if you’re diabetic, British researchers found.

According to their study published in the American Journal of Kidney Diseases, people eating less than one serving of fish each week were four times more likely to have albumin in their urine than people who ate fish twice a week.

The presence of albumin in someone’s urine is one of the earliest signs of kidney disease, a serious complication of diabetes, says study co-author Amanda Adler, an epidemiologist with the Medical Research Council Epidemiology Unit at Addenbrooke’s Hospital in Cambridge.

The study had 22,300 participants, 517 of whom had diabetes, especially type 2 diabetes.

People who often include fish in their diet might also have other lifestyle factors that reduce the risk of kidney damage, Adler said. That’s why she couldn’t tell for sure whether it was the fish that improved the diabetics’ kidneys or something else in their life style. Also, the study didn’t specify what kind of fish was involved in the participants’ diet: fried or unfried fish, warm-water or cold-water fish.

Whether or not the fish benefits diabetics, the US National Kidney Foundation encourages them to keep a tight control of glucose and blood pressure, to quit smoking and to follow a diabetic diet as prescribed by a doctor in order to keep levels of albumin down.

An estimated 23.6 million Americans have diabetes, the leading cause of end-stage kidney disease. A balanced diet and lifestyle that includes regular exercise and weight loss for those who are overweight or obese slow the progression of diabetes’ complications.