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8 Health Benefits of Magnolia Bark + Dosage, Side Effects

Written by Carlos Tello, PhD (Molecular Biology) | Last updated:
Jonathan Ritter
Puya Yazdi
Medically reviewed by
Jonathan Ritter, PharmD, PhD (Pharmacology), Puya Yazdi, MD | Written by Carlos Tello, PhD (Molecular Biology) | Last updated:

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Magnolia bark is a staple of traditional Chinese medicine and is used today for a variety of potential health benefits ranging from the treatment of depression and insomnia to improving oral health. The bark possesses calming, antimicrobial, anti-inflammatory, and antioxidant effects. Read on to find out the benefits, dosage, and side effects of taking magnolia bark.

What Is Magnolia Tree/Bark?

The magnolia tree (Magnolia officinalis), known as Houpu in Chinese medicine, is found in Southeast Asia. It was traditionally used to treat gastrointestinal (GI) disorders, anxiety, depression, nervous disorders, asthma, and allergic diseases.

The magnolia tree has a fragrant aroma and bright flowers. During the summer, the root and bark from the trees are harvested, dried, slightly boiled, and let to turn a purple-brown color. After being softened by steaming and rolling, this bitter and fragrant extract is used in medicine and dietary supplements for its potential health benefits [1].

Magnolia bark extract is often used in combination with Phellodendron bark extract in a supplement called Relora that is used for anxiety [2, 1].

Components

Magnolol and honokiol are lignans that are the major active components of magnolia bark extract. Various alkaloids (aporphine and benzylisoquinoline derivatives) and volatile oils (consisting of sesquiterpenoid alcohols, α-, β-, and γ-eudesmol) make up the rest of the extract [1].

Mechanism of Action

Honokiol maintains sodium-potassium channel activity, which is vital for communications between neurons [3].

Honokiol prevents glucose intolerance, which otherwise would severely damage neuron cells because they require a high amount of energy to function [4].

Honokiol also prevented the formation of necrotic tissue in rat brains by stopping neutrophil (immune cells that kill damaged cells and harmful pathogens) activity and neutralizing reactive oxygen species such as hydrogen peroxide [4].

Honokiol prevents neurotoxicity by inhibiting the production of nitric oxide by an enzyme called nNOS. This enzyme depends on calcium, which is allowed into cells by a glutamate (a neurotransmitter) receptor called the NMDA receptor. However, if too much calcium is taken in by the cells, this leads to the production of pro-oxidants that kill cells like superoxide and peroxynitrite [5, 6, 7, 8, 4, 9].

Both honokiol and magnolol blocked glutamate receptors in mice. This prevents glutamate from binding to the NMDA receptor and activating it too much, thus preventing seizures and premature cell death. Overstimulation of NMDA receptors is associated with many neurological disorders including epilepsy, stroke, mood disorders, and Alzheimer’s [10, 11, 4].

By stimulating the GABA-A receptor, honokiol may produce a relaxing and calming effect. Honokiol also binds to the benzodiazepine site of the GABA-A receptor of neurons, possibly impacting sleep cycles and helping with insomnia [12, 4, 13].

Honokiol also activates genes controlled by the molecule Nrf2, which protects against oxidative stress [14].

Snapshot

Proponents

  • May reduce cavities, gum disease, and bad breath
  • May improve anxiety, depression, and insomnia, especially in menopausal women
  • May improve asthma and fatty liver disease
  • Few adverse effects reported

Skeptics

  • Insufficient evidence for many benefits
  • May cause bleeding and interact with anticoagulant medication

Health Benefits

Possibly Effective for:

1) Oral Health

The bacteria Streptococcus mutans can be harmful to oral health, as it creates an acidic environment that makes plaque buildup possible. This destroys enamel and leads to the formation of cavities. A sugar-free chewing gum with magnolia bark reduced the concentration of this microbe in the saliva, plaque acidity, and gum bleeding in a clinical trial on 120 people [15, 16].

Similarly, a toothpaste with magnolia bark extract reduced plaque buildup and improved gum disease in a clinical trial on 48 people after 6 months [17].

Magnolol and honokiol were possibly responsible for these effects since they had antimicrobial activity against Streptococcus mutans in a cell-based study [18].

Other chewing gums with magnolia bark extract and antimicrobial zinc salts (zinc acetate and zinc lactate) improved bad breath (measured as volatile sulfur-containing compounds) in 2 clinical trials on over 200 people. Bad breath is mainly caused by bacterial growth on the tongue [19, 20].

Although limited, the evidence suggests that magnolia bark may help prevent cavities, gum disease, and bad breath. You may discuss with your dentist if it may be helpful as a complementary approach. Importantly, never use it as a replacement of what your dentist recommends or prescribes.

2) Menopausal Symptoms

In 2 studies of over 700 menopausal women, tablets containing a combination of magnolia extract and a soy-based supplement were given once a night for 12-24 weeks. Magnolia extract improved anxiety, insomnia, depression, and libido, while the soy isoflavones were more effective for hot flashes, vaginal dryness, nocturnal sweating, and palpitations [21, 22].

Taken together, the evidence suggests that magnolia bark extract may help with the psycho-affective symptoms of menopause. You may take this extract as an add-on to your treatment regime if your doctor determines that it may help you.

3) Anxiety

In a small trial on 28 women with eating disorders caused by stress, a dietary supplement with magnolia bark and Phellodendron extract helped prevent weight gain by reducing cortisol levels and perceived stress [23].

In another trial on 26 premenopausal women aged 20 to 50, the same supplement relieved mild transitory but not long-standing anxiety or depression [24].

As previously mentioned, another supplement with magnolia extract and soy isoflavones improved anxiety (among other menopausal symptoms) in 2 studies of over 700 postmenopausal women [21, 22].

Honokiol has been shown in animal studies to reduce anxiety with fewer side effects than diazepam, a drug commonly prescribed for anxiety disorders. Honokiol increases GABA levels, which helps decrease anxiety [4, 13].

Again, limited evidence suggests that magnolia bark may help with anxiety (especially in people with transitory anxiety and menopausal women). Discuss with your doctor if this complementary strategy is recommended in your case.

4) Depression

The above-described tablets with magnolia bark and soy isoflavones also improved depressed mood in over 700 menopausal women taking them [21, 22].

Honokiol and magnolol produced antidepressant effects and improved the energy levels in mice by increasing their serotonin and noradrenaline levels in the prefrontal cortex [25].

Serotonin is a neurotransmitter that allows for rapid signaling between neurons in the brain. Psychological disorders such as depression, mania, and anxiety are often linked to low levels of serotonin [26, 27].

Noradrenaline (norepinephrine) is a neurotransmitter that is heavily involved with the onset of depression. Low levels of noradrenaline can cause decreased energy, inability to concentrate, decreased alertness, and decreased cognitive abilities. Noradrenaline is also involved in regulating emotions [28].

Limited evidence suggests that magnolia bark may help with depression, at least in the case of menopausal women. You may discuss its potential use as an add-on to your therapy with your doctor. Never take magnolia bark in place of what your doctor recommends or prescribes.

5) Insomnia

The combination of magnolia bark and soy isoflavones mentioned above also improved insomnia in 2 studies of over 700 menopausal women [21, 22].

Honokiol promoted NREM, or dreamless sleep, in mice. Magnolol increased both NREM and REM sleep episodes by increasing the amount of GABA released from neurons in the brain. Magnolia extract overall was found to exhibit a relaxing effect [29].

Again, the evidence is limited but suggests that magnolia bark may help with insomnia (at least, if it occurs as a result of menopause). You may take magnolia bark for this purpose if your doctor determines that it may be helpful in your case.

Insufficient Evidence for:

1) Asthma

In a study of 148 mild and moderate asthma patients taking corticosteroids for their condition, magnolia extract was effective in improving asthma control and preventing extreme attacks [30].

A cell study done on immune cell production showed that magnolia extract can block the type 4 allergic reaction (delayed response type caused by the overactivity of T lymphocytes, which are involved in the adaptive immune system). Magnolol and honokiol provide a relaxing effect that may dilate bronchial vessels in the lungs, allowing for easier breathing, as seen in a study involving pig trachea contraction and relaxation [1].

A single clinical trial and a study in cells are insufficient to conclude for certain that magnolia bark improves asthma. Further clinical research is required.

2) Fatty Liver

In a clinical trial on 74 people with non-alcoholic fatty liver disease, magnolia extract tablets (400 mg/day but not 133 mg/day) taken for 12 weeks reduced liver fat content and liver damage (measured as blood ALT levels) [31].

Again, a single clinical trial cannot be considered sufficient evidence that magnolia bark helps with fatty liver disease. More clinical trials on larger populations are needed to validate these promising results.

3) Weight Loss

In a clinical trial on 28 people with eating disorders caused by stress, a dietary supplement with magnolia bark and Phellodendron extract prevented weight gain by reducing anxiety [23].

However, the supplement had no effect on appetite and weight in another trial on 26 non-stressed women [24].

Magnolia bark extract decreased body fat mass in mice. Honokiol significantly lowered triglyceride and cholesterol levels and decreased insulin resistance, preventing fat storage [32].

Two small trials (with opposite results) and an animal study are clearly insufficient to support the use of magnolia bark in weight loss. Larger, more robust clinical trials are needed to shed some light on this potential benefit.

Animal and Cell Research (Lack of Evidence)

No clinical evidence supports the use of magnolia bark for any of the conditions listed in this section. Below is a summary of the existing animal and cell-based research, which should guide further investigational efforts. However, the studies should not be interpreted as supportive of any health benefit.

Brain Function

Scopolamine is an anti-nausea drug that causes memory and learning impairments. Honokiol improved spatial learning and memory function in mice given scopolamine and reduced levels of the proinflammatory cytokines IL-1β while increasing levels of the anti-inflammatory cytokine IL-10 [33].

An alcohol extract of magnolia bark helped prevent memory loss caused by bacterial lipopolysaccharides in mice. Lipopolysaccharides are a toxin found in Gram-negative bacteria that activates the cells that protect the brain from attack from pathogens (microglia) by triggering the release of cytokines.

Magnolol and honokiol decreased brain cell death by protecting them from high calcium levels and inhibiting caspase, an enzyme that breaks down muscle-specific proteins and causes cell death. They also limited the activity of the B-secretase enzyme, which is overactive in Alzheimer’s disease patients and leads to the buildup of amyloid plaque [34, 1].

Inflammation and Pain

Cytokines are the signaling molecules of the immune system that impact the severity of inflammation, which contributes to swelling, pain, and other typical side effects of inflammation.

In a study in which magnolia bark extract was administered to cells involved in the initial immune response (activated fibroblasts and monocytes), the extract effectively lowered the number of proinflammatory cytokines IL-6, IL-8, MMP-2, and MMP-9 [35].

Honokiol and magnolol reduced pain caused by drug-induced inflammation in mice but did not reduce pain caused by heat or force [36].

Glutamate and glutamate receptors, as well as the inflammatory molecules substance P and prostaglandin E2, are known to increase the sensitivity to pain. One study found that honokiol and magnolol prevented inflammatory pain in mice injected with glutamate [11].

Diabetes

Magnolol and honokiol reduced fasting blood sugar levels, increased sugar tolerance of cells, and increased insulin levels all without causing weight gain in type 2 diabetic rats [1].

Seizures

Honokiol helped prevent and reduce the severity of seizures and reduced movement impairments in mice by blocking NMDA receptors [37].

High Blood Pressure

Honokiol significantly relaxed aortas and reduced blood pressure in rats with high blood pressure [38].

Enlarged Prostate

In a cell study, prostate gland tissue treated with honokiol reduced smooth muscle contraction and excessive cell growth [39].

Cancer

Below, we will discuss some preliminary research on magnolia bark’s potential anticancer effects. It’s still in the animal and cell stage and further clinical studies have yet to determine if its extract may be useful in cancer therapies.

Do not under any circumstances attempt to replace conventional cancer therapies with magnolia bark or any other supplements. If you want to use it as a supportive measure, talk to your doctor to avoid any unexpected interactions.

Honokiol inhibits the activity of the proteins Nf-kB and STAT3 (transcription factors), which prevent cancer cell communication and tumor spread and growth. Also, by preventing the activation of STAT3, honokiol decreases the activation of the signaling molecules c-Src and EFGR, which are often abundant in cancer cells [40].

Honokiol applied to the skin of mice resulted in an 80% decrease in benign tumor size and a 62% decrease in the progression of benign tumors to malignant tumors [40].

Mice with lung cancer treated with honokiol and radiation saw a 78% reduction in tumor volume. This combination was more effective than either honokiol or radiation alone [41].

Honokiol prevented the growth of various types of breast cancer cells and also made drug treatment more effective by blocking the production of P-glycoprotein (a protein that pumps foreign substances out of cells, thus reducing the effectiveness of chemotherapy) [40].

Mice containing human ovarian cancer cells treated twice weekly with honokiol saw an 88% inhibition in tumor growth and an increased lifespan [42].

Honokiol-containing human prostate cancer cells administered orally to mice increased the amount of cell death (apoptosis) at tumor sites and slowed the growth of cancer [43].

A cell study involving human colorectal cancer cells found that honokiol increased cell death at tumor sites and prevented tumor growth [44].

Honokiol caused cell death in human stomach cancer cells and in mice with this cancer type. It also decreased the production of key molecules involved in tumor growth (PPAR-gamma, COX-2, and 15-lipoxygenase (LOX)-1) [45].

A cell study on human pancreatic cancer cells found that honokiol caused cancer cell death and increased the effectiveness of the chemotherapeutic drug gemcitabine [46].

Limitations & Caveats

While some research supports the use of magnolia bark in benefiting multiple conditions (especially related to oral health and psycho-affective disorders), a lot of studies on potential benefits have been conducted in rodents. Caution is warranted when applying this information for use in humans.

Side Effects & Precautions

Side Effects

Keep in mind that the safety profile of magnolia bark is relatively unknown, given the lack of well-designed clinical studies. The list of side effects below is not a definite one and you should consult your doctor about other potential side effects based on your health condition and possible drug or supplement interactions.

At high doses (greater than 9 g), excessive bleeding or neurotoxicity can occur [4, 47].

Those with a bleeding disorder or clotting disorder are not recommended to take magnolia supplements. This includes those who have hemorrhages or patients with disorders such as hemophilia or von Willebrand’s deficiency [4].

Multiple animal studies reported no change in diet, appetite, weight, or other body activities. No mutations were observed and toxicity tests done over 90 days reported no mortalities [40].

Contraindications

Menopausal women taking magnolia supplements to help with insomnia, anxiety, and depression may experience constipation, breast tension, blood loss, and stomach pain [21].

Drug Interactions

Supplement/Herb/Nutrient-drug interactions can be dangerous and, in rare cases, even life-threatening. Always consult your doctor before supplementing and let them know about all drugs and supplements you are using or considering.

Patients taking anticoagulants such as Coumadin or Lovenox should not take magnolia bark extract as it reduces blood clotting [4].

Supplementation

Magnolia bark supplements have not been approved by the FDA for medical use due to the lack of solid clinical research. Regulations set manufacturing standards for them but don’t guarantee that they’re safe or effective. Speak with your doctor before supplementing with magnolia bark.

Dosage

Because magnolia bark is not approved by the FDA for any condition, there is no official dose. Users and supplement manufacturers have established unofficial doses based on trial and error. Discuss with your doctor if magnolia bark may be useful as a complementary approach in your case and which dose you should take.

Dietary supplements often contain magnolia bark extract in doses between 200 mg to 800 mg to be taken daily [1].

User Experiences

The opinions expressed in this section are solely those of magnolia bark users, who may or may not have medical or scientific training. Their reviews do not represent the opinions of SelfHacked. SelfHacked does not endorse any specific product, service, or treatment.

Do not consider user experiences as medical advice. Never delay or disregard seeking professional medical advice from your doctor or other qualified healthcare providers because of something you have read on SelfHacked. We understand that reading individual, real-life experiences can be a helpful resource, but it is never a substitute for professional medical advice, diagnosis, or treatment from a qualified healthcare provider.

One user noted that they fell asleep much quicker and had better sleep.

Another user reported experiencing better sleep and lowered anxiety levels. However, they noted that the effect diminished after a couple of days.

Some users reported headaches and drowsiness as main side effects.

About the Author

Carlos Tello

Carlos Tello

PhD (Molecular Biology)
Carlos received his PhD and MS from the Universidad de Sevilla.
Carlos spent 9 years in the laboratory investigating mineral transport in plants. He then started working as a freelancer, mainly in science writing, editing, and consulting. Carlos is passionate about learning the mechanisms behind biological processes and communicating science to both academic and non-academic audiences. He strongly believes that scientific literacy is crucial to maintain a healthy lifestyle and avoid falling for scams.

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