Protective Effects of Japanese Soybean Paste (Miso) on Stroke in Stroke-Prone Spontaneously Hypertensive Rats (SHRSP)

Abstract BACKGROUND AND HYPOTHESIS Soybean isoflavones have been shown to reduce the risk of cerebral infarction in humans according to epidemiological studies. However, whether intake of miso can reduce the incidence of stroke in animal models remains unknown. In this study, we investigated the effects of soybean paste (miso) in an animal model of stroke. METHODS Stroke-prone spontaneously hypertensive rats (SHRSP) were fed a miso diet (normal diet 90%, miso 10%; final NaCl content 2.8%), a high salt diet (normal diet and NaCl 2.5%; final NaCl content 2.8%), or a low salt diet (normal diet; final NaCl content 0.3%). RESULTS Kaplan–Meier survival curves revealed a significantly lower survival rate in the high salt group compared to the miso group (P = 0.002) and the low salt group (P ≤ 0.001). Large hemorrhagic macules were found in the cerebrum in the high salt group, whereas none were found in the other 2 groups. There were also fewer histological and immunohistochemical changes in the brain and kidneys in the miso group compared to the high salt group. CONCLUSION Our results suggest that miso may have protective effects against stroke despite its high salt content.