Intake of residuals from Atlantic cod attenuated blood pressure increase but did not delay development of kidney damage in obese Zucker fa/fa rats

BACKGROUND: Documentation of health effects of residuals after fish filleting may motivate both consumers and producers to increase the use of this under-utilised protein source. OBJECTIVES: The primary objective of the present study was to investigate the effects of a diet containing residuals from Atlantic cod (Gadus morhua) filleting on the development of high blood pressure in obese Zucker fa/fa rats, which spontaneously develop hypertension and proteinuria. The secondary objectives were to investigate any changes in kidney morphology, kidney function and organ damage, and to determine the potential inhibition of cod residuals on renin and angiotensin-converting enzyme (ACE) activities in vitro. METHODS: Male rats were fed diets containing protein powder prepared from head, backbone and skin fraction (HBS, n = 6) from Atlantic cod as 25% of total protein with the remaining 75% as casein, or casein as the sole protein source (Control group, n = 6) for 4 weeks. Blood pressure was measured on day 0, 14 and 26. Kidneys were analysed morphologically, and markers for renal function and organ damage were analysed biochemically. RESULTS: The HBS diet attenuated the blood pressure increase compared to the Control group, but kidney damage and dysfunction were similar between the two groups. CONCLUSION: A diet containing a protein powder consisting of HBS fraction from cod attenuated the blood pressure increase in obese Zucker fa/fa rats, without preventing kidney damage.