Limited evidenceJoints & skin

Drynaria (Gu Sui Bu)

A fern rhizome used in Chinese medicine for fractures and bone loss. Standardized flavonoid extracts have been tested in Chinese trials with effects on bone turnover markers, but the trials are small, mostly published in Chinese databases, and no fracture outcome has been shown.

Evidence last reviewed: August 2026

What the science says

Bone metabolism markers Limited evidence
A systematic review and meta-analysis of nine randomized trials of total flavonoids of Rhizoma Drynariae reported higher bone formation markers (osteocalcin, P1NP, alkaline phosphatase) and lower bone resorption marker TRACP compared with control therapies. These are biochemical surrogates, and most included trials were small and from a single country's literature.
Postmenopausal osteoporosis Limited evidence
A randomized trial in elderly women with postmenopausal osteoporosis reported improvements in lipid profile and inflammatory markers with Drynaria fortunei alongside standard care. It was a single small trial with mechanistic rather than clinical endpoints.
Fracture healing Limited evidence
The traditional indication — speeding fracture repair — rests on animal models and clinical impression. No adequately powered randomized trial has measured fracture healing time or refracture rates.

Dosage & safety

Studied doseTraditional decoctions use 9–15 g of dried rhizome per day. The trials used standardized total-flavonoid extracts, whose dosing is not interchangeable with raw powdered rhizome sold in capsules.

SafetyLimited safety data outside traditional use. Reported adverse effects are mainly mild gastrointestinal. Avoid in pregnancy and breastfeeding for lack of data. Because trial products were standardized extracts made to pharmaceutical specification, the quality and content of consumer capsules may differ substantially. It should not replace evaluated treatment for osteoporosis.

Scientific references

Effects of total flavonoids of Rhizoma Drynariae on biochemical indicators of bone metabolism: a systematic review and meta-analysis
Li W, Zhang Z, Li Y, Wu Z, Wang C, Huang Z — Front Pharmacol, 2024
Drynaria fortunei improves lipid profiles of elderly patients with postmenopausal osteoporosis via regulation of Notch1-NLRP3 inflammasome-mediated inflammation
Lu L, Wang Z, Zhang H, Liu T, Fang H — Gynecol Endocrinol, 2022

Where to buy

View on iHerb

Referral link — this site may earn a commission on purchases.

Related in Joints & skin

Curcumin (Turmeric extract) Moderate evidence
Collagen Peptides Moderate evidence
Glucosamine Limited evidence
Biotin (Vitamin B7) Limited evidence
MSM (Methylsulfonylmethane) Limited evidence
Chondroitin Sulfate Moderate evidence