Meta Information
ID:phytoestrogens-soy-isoflavones
Name:Phytoestrogens (Soy Isoflavones)
Schema Version:2.4_uniform_evidence_2026_06_18
Created
2026-07-02T07:04:56Z
Model
phase-b-newfiles-claude-opus-4.8
Interactions
Target id:
/class/serms
Target name:
SERMs (tamoxifen, raloxifene)
Severity:
moderate
Interaction type:
diminishing
Nature:
relative
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Soy isoflavones bind estrogen receptors and could theoretically interfere with the anti-estrogen action of SERMs like tamoxifen.
Actionable advice:
High-dose soy isoflavone supplements are best avoided when taking tamoxifen for breast cancer; it is a good idea to discuss this with an oncologist.
Validation status:
validated_via_class_inference
Evidence tier:
tier_c
Evidence basis:
class_inference_summary
Evidence anchors:
Source url:
Established mechanism / class pharmacology (no single primary source quoted)
Exact phrase from label:
Isoflavones are ER ligands; may oppose SERM anti-estrogen effect. Theoretical, debated.
Label source:
Class inference
Action type:
avoid
Target id:
/intervention/levothyroxine
Target name:
Levothyroxine
Severity:
moderate
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
4
Hours after target:
4
Description:
Soy reduces the absorption of levothyroxine, potentially undertreating hypothyroidism.
Actionable advice:
Soy/isoflavone products and levothyroxine should be separated by at least 4 hours.
Validation status:
validated_via_class_inference
Evidence tier:
tier_c
Evidence basis:
class_inference_summary
Evidence anchors:
Source url:
Established mechanism / class pharmacology (no single primary source quoted)
Exact phrase from label:
Soy reduces levothyroxine absorption (documented); separate dosing. Established.
Label source:
Class inference
Action type:
separate
Target id:
/condition/hormone-sensitive-cancer
Target name:
Hormone-sensitive cancers
Severity:
moderate
Interaction type:
adverse
Nature:
conditional
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
High-dose isoflavones have estrogenic activity that is of theoretical concern in hormone-sensitive cancers (evidence is mixed).
Actionable advice:
It is important to talk to an oncologist about high-dose soy isoflavone supplements with a hormone-sensitive cancer.
Validation status:
validated_via_class_inference
Evidence tier:
tier_c
Evidence basis:
class_inference_summary
Evidence anchors:
Source url:
Established mechanism / class pharmacology (no single primary source quoted)
Exact phrase from label:
Isoflavones are weak estrogen-receptor agonists; theoretical concern in hormone-sensitive malignancy (evidence mixed).
Label source:
Class inference
Action type:
monitor