1. To assess the effect of dietary
phytosterol on
stroke and the lifespan of
salt-loaded
stroke-prone spontaneously hypertensive rats (SHRSP), we investigated the effects of the addition of
phytosterol to
soybean oil (
phytosterol content: 0.3%) on
stroke onset, lifespan following onset of
stroke and overall lifespan compared with
canola oil (
phytosterol content: 0.9%). 2. Six-week-old male SHRSP were fed a test diet prepared by the addition of
canola oil (CA diet),
soybean oil (SO diet),
soybean oil plus 0.6%
phytosterol (SO + 0.06P diet) or
soybean oil plus 4.5%
phytosterol (SO + 0.45P diet) as
a 10% fat source. 3. Systolic blood pressure (SBP) increased in the SO + 0.06P and SO + 0.45P groups compared with the SO group and the increase was dependent on the amount of
phytosterol added, indicating that the addition of
phytosterol to
soybean oil may promote an increase in SBP in
salt-loaded SHRSP. 4. The onset of
stroke was shortest in the SO + 0.45P group and survival after the onset of
stroke was shortest in the CA group. Consequently, the SO + 0.45P and CA groups showed marked lifespan shortening, indicating that a fivefold greater amount of
phytosterol was required to produce an effect equivalent to that of
canola oil. 5. Investigation of the
mRNA expression of
ATP-binding cassette (
ABC) transporters involved in intestinal
phytosterol absorption indicated significant decreases in the intestinal
mRNA expression of Abcg5 and Abcg8 in SHRSP and Wistar-Kyoto rats compared with Wistar rats. 6. In conclusion, the addition of
phytosterol to
soybean oil elevated SBP and promoted the onset of
stroke, which may cause a reduction in survival time. However, a fivefold greater amount of
phytosterol was required to produce an effect that was equivalent to the survival time-shortening effect of
canola oil. The significant decrease in the intestinal
mRNA expression of Abcg5 and Abcg8 in SHRSP may be responsible, at least in part, for the unfavourable effects observed following the addition of
phytosterol.