Positives

• A meta-analysis of 8 trials demonstrated red clover isoflavones produced a statistically significant reduction in daily hot flush incidence in postmenopausal women (weighted mean difference -1.73 hot flushes/day) — relevant for the Long COVID patients whose symptoms overlap with menopausal vasomotor instability Maturitas.
  
  
• A randomized study found red clover isoflavone supplementation in postmenopausal women significantly decreased menopausal symptoms and produced positive effects on vaginal cytology and triglyceride levels compared with placebo PubMed.
  
  
• A 2022 trial of fermented red clover extract in early post-menopausal women showed reduced vascular inflammation markers, suggesting potential cardiovascular relevance for Long COVID patients with overlapping endothelial dysfunction Frontiers in Cardiovascular Medicine.
  
  

Negatives

• Other studies have shown red clover supplementation produced no significant difference from placebo on quality-of-life measures, and a 2021 systematic review concluded effects on hot flushes are clinically modest at best PMC.
  
  

Hurdles & Side Effects

• Doses providing up to 80 mg of isoflavones daily for up to 2 years are considered possibly safe; common mild side effects are nausea, bloating, and headache, but the effects on long-term breast tissue have not been fully characterized WebMD.