Effects of 90-Day Oral Administration of Fermented Soybean Extract in Rats

 

A 90-day study examined the effects of fermented soybean extract (not just isoflavones) administered orally at doses of 8, 56, and 400 mg/kg/day in male and female rats. Key findings included:

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Effects on Body Weight:

• Male rats in the 56 mg/kg and 400 mg/kg groups showed a decrease in body weight.

• Female rats in the 400 mg/kg group also experienced weight reduction.

 

Pathohistological Findings:

• Kidney abnormalities:

  • Calcium deposits were found in the kidneys of male rats in the 56 mg/kg and 400 mg/kg groups.

• Prostate gland abnormalities (male rats at 400 mg/kg):

  • Epithelial hyperplasia (excessive cell growth in the lining of the prostate).

  • Formation of cysts within the prostate tissue.

  • Depletion of secretory fluid, which may indicate dysfunction in prostate gland activity.

  • Hypersecretion of epithelial cells, suggesting increased glandular activity.

 

These findings indicate that high doses of fermented soybean extract may have negative effects on male reproductive health, particularly the ventral prostate, and could contribute to kidney dysfunction due to calcium deposition. The weight loss observed in both male and female rats suggests possible metabolic effects of prolonged soybean extract consumption.

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Citation : Sato T, Yamakoshi J, Saito M, Kikuchi M. Acute and Subchronic Toxicity studies of fermented soybean extract by Oral Administration in F344 Rats. Oyo Yakuri/Pharmacometrics (2002) 63:105-118.