Benefits
Cortisol reduction in moderately stressed adults (Relora RCT)
Talbott 2013 (PMID 23924268, J Int Soc Sports Nutr) RCT in 56 subjects (35 men, 21 women) screened for moderate stress. After 4 weeks of Relora supplementation, salivary cortisol exposure was significantly LOWER (-18%) in Relora group vs placebo (p<0.05). The strongest evidence-supported claim for Relora — meaningful effect size for non-pharmaceutical stress intervention.
Mood state improvement (POMS scores)
Talbott 2013 same trial: Relora group showed significantly better Profile of Mood States (POMS) scores vs placebo: Overall Stress -11%, Tension -13%, Depression -20%, Anger -42%, Fatigue -31%, Confusion -27%, Global Mood +11%, Vigor +18%. Multi-dimensional mood improvement in moderately stressed but otherwise healthy adults — useful for everyday stress management context.
Mild transitory anxiety reduction (Kalman 2008 pilot)
Kalman 2008 (PMID 18426577, Nutr J) pilot RCT in 40 premenopausal women given Relora 250 mg 3x daily vs placebo for 6 weeks. RESULT: Relora reduced TEMPORARY/TRANSITORY anxiety (Spielberger STATE) but NOT long-standing anxiety/depression (Spielberger TRAIT). MIXED outcomes: salivary cortisol/amylase, appetite, body morphology, sleep quality NOT significantly changed vs placebo. Important nuance — Relora may help acute/situational stress but not chronic anxiety disorders.
Weight management in stress-eaters (Garrison 2006)
Garrison 2006 (PMID 16454147) pilot RCT in overweight premenopausal women (BMI 25-34.9) who eat in response to stress. After 6 weeks of Relora 250 mg 3x daily: NO significant weight gain in treatment group vs placebo group which gained 1.5 kg (p<0.01). 75% of placebo were 'gainers' (≥1 kg) vs 37% of treatment group (p<0.04). Useful for STRESS-related eating subgroup specifically, not general weight loss.
Anti-inflammatory and antimicrobial effects (TCM traditional + mechanistic)
Phellodendron bark (Huang Bai) used in TCM for inflammation, infection, joint pain — supported by berberine's well-documented antimicrobial activity (vs bacteria, fungi, parasites) and anti-inflammatory NF-κB inhibition. See Berberine entry for detailed evidence on the principal active compound. Phellodendron's berberine content (~1-2%) is substantially less than Goldenseal or Barberry concentrations.
Mechanism of action
GABAergic activity and HPA axis modulation (Relora/honokiol mediated)
The Relora cortisol-reducing effect is primarily attributed to MAGNOLIA's honokiol (GABA receptor modulator) rather than Phellodendron alone. Phellodendron contributes synergistic effects via berberine. Combined product modulates HPA axis stress response — reducing CRH/ACTH/cortisol cascade. Animal models confirm anxiolytic effect via GABA pathway.
Berberine — AMPK activation, antimicrobial, lipid effects
Berberine activates AMPK (insulin sensitivity, glucose/lipid metabolism), inhibits multiple bacteria/fungi/parasites, and reduces inflammation via NF-κB inhibition. Phellodendron is one of multiple traditional berberine sources (alongside Coptis chinensis, Goldenseal, Barberry). See Berberine entry for detailed mechanism.
Anti-inflammatory NF-κB inhibition
Berberine and obacunone inhibit NF-κB activation, reducing inflammatory cytokine production. Mechanism for traditional anti-inflammatory uses (joint pain, GI inflammation, skin conditions) and complementary to Magnolia's effects in Relora combination.
5-HT and dopamine modulation (mood effects)
Relora's mood-enhancing effects involve serotonin and dopamine modulation in addition to cortisol reduction. Animal studies show Relora components enhance neurogenesis and BDNF expression — relevant to depression/mood applications. Combined effect of multiple components likely.
Clinical trials
Randomized double-blind placebo-controlled trial (Talbott SM, Talbott JA, Pugh M 2013, J Int Soc Sports Nutr 10(1):37, doi:10.1186/1550-2783-10-37, PMID 23924268). PMC3750820.
56 subjects (35 men, 21 women) screened for moderate stress, supplemented with Relora (Magnolia officinalis + Phellodendron amurense bark extracts) or placebo for 4 weeks.
Relora group: salivary cortisol exposure -18% (p<0.05) vs placebo. Significantly better mood: Overall Stress -11%, Tension -13%, Depression -20%, Anger -42%, Fatigue -31%, Confusion -27%, Global Mood +11%, Vigor +18%. Authors concluded Relora reduces cortisol exposure and perceived daily stress while improving multiple mood parameters. Strongest single trial supporting Phellodendron-containing product for stress/mood applications.
Pilot, double-blind, placebo-controlled clinical trial (Kalman DS, Feldman S, Feldman R, Schwartz HI, Krieger DR, Garrison R 2008, Nutr J 7:11, doi:10.1186/1475-2891-7-11, PMID 18426577). PMC2359758.
40 healthy overweight (BMI 25-34.9) premenopausal women (ages 20-50) who eat more in response to stress and score above national mean for women on self-reporting anxiety. Randomized to Relora 250 mg 3x daily or placebo for 6 weeks.
Relora EFFECTIVE for reducing temporary/transitory anxiety (Spielberger STATE questionnaire) vs placebo. Relora NOT EFFECTIVE for long-standing anxiety or depression (Spielberger TRAIT). Salivary cortisol, amylase, appetite, body morphology, sleep NOT significantly changed. Mixed findings — Relora may help acute/situational anxiety but not chronic anxiety disorders. Important nuance for clinical positioning.
Randomized double-blind placebo-controlled clinical study (Garrison R, Chambliss WG 2006, Altern Ther Health Med 12(1):50-54, PMID 16454147).
Overweight (BMI 25-34.9) premenopausal female adults (ages 20-50) who typically eat more in stressful situations and scored above national mean for women on self-reported anxiety. Two 250-mg capsules or identical placebo capsules 3x daily for 6 weeks. Outcomes: salivary cortisol, weight change, psychological measures.
28 subjects completed. Significant weight gain in placebo group (+1.5 kg, p<0.01); NO significant weight gain in Relora group (+0 kg, p=0.89). 75% of placebo were 'gainers' (≥1 kg) vs 37% of treatment group (p<0.04). Useful for stress-related eating subgroup specifically — not general weight loss intervention.
About this ingredient
Phellodendron amurense (Amur cork tree, 黄柏 huang bai) is a deciduous tree of the Rutaceae family native to East Asia (China, Korea, Japan, Russian Far East). The dried inner bark has been used in TCM for over 2,000 years (catalogued in Shennong Bencaojing) for: damp heat conditions, inflammation, infection, joint pain, GI complaints, urinary disorders. PHYTOCHEMISTRY: ALKALOIDS — primarily BERBERINE (1-2% of bark — yellow color, primary bioactive); PALMATINE; JATRORRHIZINE; MAGNOFLORINE.
LIMONOIDS — obacunone (anti-inflammatory). OTHER — phenolic compounds, polysaccharides. Berberine content is substantially less than Coptis chinensis (Huang Lian, 5-8%) or Goldenseal (~5%) — Phellodendron is a 'mid-range' berberine source.
RELORA® (the principal Western product): proprietary blend of Magnolia officinalis bark + Phellodendron amurense bark extracts standardized to honokiol (Magnolia) and berberine (Phellodendron) developed by Next Pharmaceuticals. 250 mg capsules contain ~125 mg Magnolia + ~125 mg Phellodendron extract. Most published clinical evidence is for the COMBINATION rather than Phellodendron alone — challenges attribution of effects.
Used in TCM individually and in classical formulas (San Miao San, Yu Dai Wan for vaginal discharge, Yi Yi Ren Tang). EVIDENCE: 3/5 reflects: (1) Talbott 2013 PMID 23924268 RCT n=56 demonstrating significant cortisol reduction (-18%) and mood improvement, (2) Kalman 2008 PMID 18426577 pilot RCT showing benefit for transitory but not chronic anxiety, (3) Garrison 2006 PMID 16454147 weight management in stress-eaters, (4) extensive berberine evidence base (see Berberine entry), (5) 2,000+ years of TCM use. Limited by: combination product confounds attribution, industry-sponsored research, small sample sizes, and short trial durations (4-6 weeks).
SAFETY: Generally well-tolerated; pregnancy avoid. Best positioned as: (a) Relora-form (combination with Magnolia) for stress and cortisol management — particularly useful for stress-eaters and moderately stressed adults, (b) NOT recommended for chronic anxiety disorders based on Kalman 2008 negative TRAIT findings, (c) traditional Phellodendron uses (anti-inflammatory, antimicrobial) overlap heavily with berberine evidence — see Berberine entry, (d) component of TCM formulas under practitioner guidance. Honest framing: meaningful evidence base for Relora-form stress/cortisol applications; the Phellodendron-specific contribution (vs Magnolia or berberine) is harder to isolate.