The study was the work of Dr Amanda Adler, of the Epidemiology Unit of the Medical Research Council, based at Addenbrooke's Hospital, in Cambridge, and colleagues, and is published in the November printed issue of the American Journal of Kidney Diseases, the official journal of the National Kidney Foundation in the US.
Kidney disease is a serious side effect of diabetes which causes scarring in the filtering units of the kidneys and hampers their ability to clean the blood. One sign of kidneys beginning to fail is albuminuria or protein in the urine.
Eventually when the kidneys fail completely patients need kidney dialysis or a transplant. Protein in the urine is also linked to a higher risk of heart disease.
Adler and colleagues looked at the results of urine tests and diet and lifestyle questionnaires from over 22,000 middle-aged and older men and women, which included questions about how often they ate fish. 517 of the participants had diabetes. All the participants had taken part in a 10-country European study of the links between cancer and diet that ran from 1994 to 1997.
The results showed that:
- 22.6 per cent of the participants with diabetes had microalbuminuria compared to 11.4 per cent of those without diabetes.
- The participants with diabetes who ate on average less than one serving a week of fish were four times more likely to have microalbuminuria compared to those who ate at least two servings a week.
- 18 per cent of the participants who reported low fish consumption had protein in their urine versus 4 per cent who reported eating fish on a regular basis.
"Greater fish intake was associated with a lower risk of macroalbuminuria in a self-defined diabetic population. These findings merit confirmation in prospective studies and intervention trials and suggest that fish intake may be beneficial for albuminuria in people with diabetes."
Adler said that it was possible there might be other reasons why the fish eaters had a lower risk of albuminuria that the study was not able to account for. She said that protein in the urine was one of the earliest signs of kidney disease:
"Persistent albuminuria means that the kidney has some damage and is starting to spill protein into the urine", said Adler.
"Two positive tests for protein in the urine over several weeks indicate persistent albuminuria, a first sign of diabetic kidney disease," she added.
The researchers suggested that unique nutrients in fish may work by enhancing blood glucose control and helping to regulate an appropriate balance of blood lipids (fats).
As well as a diet that contains regular portions of fish, the National Kidney Foundation said tight glucose control also reduces the risk of albuminuria, as does reducing high blood pressure, quitting smoking and following a diabetic diet prescribed by a doctor.
Senior Vice President for Scientific Activities at the National Kidney Foundation, Dr Kerry Willis said:
"Diet is a relatively simple lifestyle change to make and the benefits could be significant."
" Cross-sectional Association Between Fish Consumption and Albuminuria: The European Prospective Investigation of Cancer-Norfolk Study."
Chee-Tin Christine Lee, Amanda I. Adler, Nita G. Forouhi, Robert Luben, Ailsa Welch, Kay-Tee Khaw, Sheila Bingham, Nicholas J. Wareham.
American Journal of Kidney Diseases, November 2008, Vol. 52, Issue 5, Pages 876-886.
Click here for Abstract.
Sources: National Kidney Foundation, journal article.