Antihypertensive Effect of Salt‐Free Soy Sauce, a New Fermented Seasoning, in Spontaneously Hypertensive Rats

  In this study, we focused on the antihypertensive effect of newly fermented salt‐free soy sauce (SFS) in spontaneously hypertensive rats (SHRs). A 13‐wk oral administration of SFS was performed daily in 8‐ to 21‐wk‐old SHRs with a dose of 200 mg/kg of body weight/d. The systolic (SBP) and diastolic (DBP) blood pressures were measured for each week during the experimental period. As a result, a significant ( P  < 0.01) BP lowering effect was observed from the 5th d to the end of the experiment in the SFS group compared with the control group (ΔSBP 21‐wk : 27 mmHg, ΔDBP 21‐wk : 20 mmHg). In contrast to such substantial effect by SFS intake, angiotensin I‐converting enzyme activities in blood and local organs as well as pharmaceutical parameters such as serum Na + or K + level did not show any significant difference between in both SFS and control groups. Vasoconstriction experiment using thoracic aorta rings from 21‐wk SHRs provided an interesting result that the rings from the SFS group evoked a >2‐fold higher increase in the angiotensin II‐stimulated constrictive response compared with the rings from the control group ( P  = 0.012), which suggested that the SFS‐intake would be effective in possessing a higher vessel tone. Practical Application: In this study, we investigated the antihypertensive effect of newly fermented SFS in SHRs. As a result of 13‐wk SFS‐administration, we found a significant antihypertensive effect of the SFS. This finding strongly demonstrates that the developed SFS would be greatly beneficial for health and useful for health‐related industries.