Black Cohosh vs Soy Isoflavones
for menopausal symptoms
Stronger evidence: Soy Isoflavones
Stronger effect: Soy Isoflavones
Safety: No notable interactions recorded for either.
For menopausal symptoms, Soy Isoflavones has the stronger evidence grade.
Black Cohosh
grade C low certainty
inconsistent evidence for hot-flash relief; some trials positive, larger ones null
40 mg/day, peri/post-menopausal women
Soy Isoflavones
grade B moderate certainty
modest reduction in hot-flash frequency/severity; effect builds over weeks
40–80 mg isoflavones/day, menopausal women
sources: PMID:10000004 · PMID:10000005