The potential of cod hydrolyzate to inhibit blood pressure in spontaneously hypertensive rats

Hypertension is an independent yet controllable risk factor for cardiovascular diseases. Synthetic angiotensin-converting enzyme (ACE) inhibitors used to treat hypertension are often associated with adverse effects, and the interest in diet-related inhibitors is increasing. We hypothesized that North Atlantic fish hydrolysate might inhibit ACE, thus preventing hypertension. We assessed the ACE inhibitory potential of various North Atlantic fish species and evaluated the effect of dietary supplementation of fish hydrolysates on the blood pressure of spontaneously hypertensive rats. Fish samples were hydrolyzed using simulated gastrointestinal digestion, and ACE inhibitory activity was evaluated using an ACE inhibitory activity assay. In vivo anti-hypertensive effects were evaluated by administering hydrolysates of wild Atlantic cod (Gadus morhua L.), haddock (Melanogrammus aeglefinus L.), or farmed Atlantic salmon (Salmo salar L.) to 10-week-old male, spontaneously hypertensive rats for 4 weeks. The dosing was 200 mg/kg body weight for 21 days, followed by 500 mg/kg body weight for 7 days. Water and Captopril (20 mg/kg body weight) were administered as the negative and positive controls, respectively. The analyzed fish hydrolysates exhibited a 50 % ACE inhibition coefficient (IC50) of 1 to 2.7 μg/mU ACE. Fish hydrolysate supplements did not significantly inhibit the increase in blood pressure during the experimental period. The group receiving cod supplement had a lower (not significant) increase in blood pressure compared to the other groups. Although further studies are necessary to verify the antihypertensive effect of cod, the results obtained in this study indicate the potential that cod hydrolysate may have in inhibiting hypertension.