Traditional uses
Magnolia has been used for thousands of years for various ailments. Magnolia bark has been used for anxiety, depression, nervousness, gastrointestinal disorders, asthma, and allergic diseases. Magnolia flower bud has been used for sinus congestion and sinus headaches. It has been used within Chinese, Japanese, Indian, and American medicine.1
Mechanism of Action
Magnolia bark extract, particularly its active compounds honokiol and magnolol, has been shown in multiple animal studies to reduce corticosterone (the animal equivalent of cortisol) and calm the HPA axis — the body's core stress-response system.
Magnolia helps to regulate neuronal function, reduce neurotoxicity, suppress apoptosis, decrease neuroinflammation, mitigate nerve oxidation.
Neolignans are the main polyphenol constituents of Magnolia that are neuroprotective. Magnolol and honokiol, two key neolignan polyphenols within Magnolia, protect nerve cells and brain microvascular endothelial cells (BMECs), thereby addressing neurological diseases (ex. Alzheimer’s Disease [AD], Parkinson’s Disease [PD]) and psychiatric disorders (ex. anxiety, depression). These polyphenols also provide gastrointestinal and cardiovascular protection (ex. stroke), as well as anti-inflammatory, antibacterial, and antioxidant support.
Neolignans can also aid in mitigating strial degeneration and reducing α-Synuclein (αS) toxicity in order to preserve dopamine neurons. They can enhance serotonergic transmission. Studies have shown that neolignans can reduce beta-amyloid (Aβ) toxicity and regulate cholinergic nerve function, thereby preserving the neurons of patients with AD.2
Magnolia has demonstrated the ability to attenuate inflammatory responses and oxidative stress.3 Magnolol & honokiol have also exhibited positive allosteric modulation of GABA_A receptors, thus providing an anxiolytic effect.4
Magnolol has been shown to mitigate pulmonary arterial hypertension, ventricular hypertrophy, and vascular remodeling, and protecting the microvascular endothelial barrier in rats.5
Evidence-based research
In a double-blind, placebo-controlled trial, a magnolia–phellodendron blend (Relora) reduced salivary cortisol in stressed adults within 2–4 weeks. The Relora group also reported lower levels of stress, anger, confusion, fatigue, as well as improved mood and vigor.6
One cup of magnolia tea daily for three consecutive weeks was shown to reduce sleep issues and symptoms of depression in a study of 50 postnatal women.7
In a study of prehypertensive rats, administration of magnolol for 3 weeks decreased blood pressure, enhanced insulin signaling and insulin-induced aorta vasodilation, and restored nitric oxide production.8 Magnolia has also promoted improvements in depressive-like behavior in mice with induced colitis.9
Safety
No adverse events were found in a study of premenopausal women taking a dose of 250mg of a combination of Magnolia/Phellodendron.10
With the exception of transient sedation and mild nausea that resolved post-infusion, a study showed no major adverse effects in two cancer patients receiving infusions of honokiol of up to 50mg/kg per individual tolerance.11
In vitro and in vivo genotoxicitiy studies of concentrated magnolia bark extract showed no mutagenicity or genotoxicity.12 No adverse effects were reported in rats given dosages of magnolia bark extract of up to 240 mg/kg/day for 90 days.13 Further dosage increases of up to 650-2500 mg/kg/day for 14 days were also well tolerated.14
Further research is needed to assess safety in pregnancy. Though there is a need for further safety data in humans, Magnolia bark has been medicinally used in Asia for thousands of years.15
Dosage
Dosages range widely for Magnolia. Herbal preparations of the bark have ranged from 3-10 grams, while the bark extract in supplement form ranges from 200-800 mg/day, depending on the concentration of the active compounds.15