Shogaol

Shogaol: A Comprehensive Encyclopedic Reference

1. Identity, Nomenclature, and Natural Source

Shogaols are pungent constituents of ginger, similar in chemical structure to gingerol. The parent plant is Zingiber officinale Roscoe (family Zingiberaceae), and Zingiber officinale is a member of the Zingiberaceae plant family, native to East and southern Asia. Its generic name Zingiber is derived from the Greek zingiberis, which itself comes from the Sanskrit name of the spice, singabera; the Latin name means "shaped like a horn" and refers to the roots, which resemble a deer's antlers.

The name "shogaol" is derived from the Japanese name for ginger (shōga, 生姜). While 6-gingerol is the most bioactive compound in fresh ginger, 6-shogaol represents the main bioactive principle in dried ginger. The pungent compound 6-shogaol was identified and first described by Nomura in 1918.

The recognized members of the shogaol family found in ginger are [4]-shogaol, [6]-shogaol, [8]-shogaol, [10]-shogaol, and [12]-shogaol. Among these, 6-shogaol is identified as the most potent. The bracketed number in each name refers to the length of the aliphatic side chain attached to the aromatic ring system.

The molecular structure of each shogaol contains a 3-methoxy-4-hydroxyphenyl (vanillyl) functional group. Based on variations in the hydrocarbon chain linked to this functional group, gingerol can be classified into shogaol, para-zingerone, zingerone, gingerdione, and related compounds.

Comparative studies demonstrate beneficial effects of 6-shogaol over 6-gingerol with regard to anticancer, antioxidative, and anti-inflammatory effects — effects that may be attributed to the chemical structure of 6-shogaol, which contains an α,β-unsaturated carbonyl moiety (a so-called Michael acceptor). This electrophilic moiety allows 6-shogaol to form covalent adducts with nucleophilic cysteine residues in target proteins, a property central to many of its biological activities.

Shogaol is rated 160,000 Scoville Heat Units (SHU) on the Scoville scale. When compared to other pungent compounds, shogaol is moderately more pungent than piperine, but about 100 times less pungent than capsaicin.

Formation and Relationship to Gingerol

6-Gingerol and its dehydrated analogue [6]-shogaol are the primary ginger-derived bioactive compounds. Shogaol (along with zingerone) is produced when fresh ginger is heated or cooked. More precisely, during storage, 6-gingerol is degraded in dried ginger, while the quantity of 6-shogaol increases due to dehydration processes. Shogaol (and gingerol) are converted to other constituents when heat is applied over time, which is why ginger loses its spiciness as it continues to cook.

The main ginger shogaol is 6-shogaol, whose concentration dramatically increases during the processing of ginger, primarily due to the heat-induced conversion of 6-gingerol. Chemically, this conversion involves dehydration of the β-hydroxy group present in gingerol, yielding the characteristic α,β-unsaturated ketone (enone) structure of shogaol.

Relative Abundance in Ginger

Phenolic substances represent the pungent principles in ginger and constitute a substantial part of its active compounds, among them gingerols (23–25%), paradols (5-deoxygingerols), and shogaols (18–25%). Gingerols and shogaols are the most prominent bioactive principles in ginger, among which the main components are 6-shogaol and 6-gingerol.

Common Forms and Preparations

Shogaol is not typically isolated or sold as a standalone dietary supplement ingredient but rather is consumed as a constituent of various ginger preparations. These include:

• Dried ginger powder — the form in which shogaol predominates, since drying converts gingerol to shogaol through heat-driven dehydration.
• Ginger oleoresin and standardized extracts — the oleoresin (oily resin) from the rhizomes of ginger contains many bioactive components including [6]-gingerol, which is believed to exert a variety of remarkable pharmacological and physiological activities, alongside shogaols.
• Encapsulated ginger supplements — dry ginger or extract preparations in capsule or tablet form.
• Nanoformulations (investigational) — nanotechnology approaches (polymer nanoparticles or micelles, liposomes, inorganic nanoparticles, and nanoemulsions) have shown advantages in enhancing the solubility of lipophilic compounds, oral absorption, and bioavailability, and in reducing required doses.
• Ginger teas and decoctions — traditional water-based preparations in which shogaol content depends on the form of ginger used and the temperature/duration of infusion.

Notably, 6-shogaol can be metabolized into 6-paradol, a compound that lacks pungency but retains biological activity.

2. Traditional and Historical Use

While the exact origin of ginger cultivation is unknown, ginger has been cultivated for over 4,000 years in China and India, reaching the Western world around 2,000 years ago. Ginger rhizome and its essential oils are used in Traditional Chinese Medicine and Ayurveda as herbal remedies for the treatment of various diseases such as cardiovascular, inflammatory, neurological, diabetic, and nephrological disorders.

It must be emphasized that traditional preparations used whole ginger or dried ginger — not isolated shogaol. Shogaol as an isolated compound was not characterized until the early twentieth century. The traditional medicinal uses described below therefore apply to ginger preparations containing shogaol (especially in dried or cooked forms) alongside many other constituents.

Ayurveda (Indian Traditional Medicine)

Ginger is one of the most important drugs of the Ayurvedic System of Medicine, known as the "universal medicine" (Viswabhesaja), found in almost all classical formulations of Ayurveda for the treatment of different diseases; the majority of Ayurvedic prescription drugs contain ginger as one of the ingredients. In Ayurveda, Zingiber officinale is used both in fresh (Ardraka) and dry (Shunthi) forms. The dry form (Shunthi), being richer in shogaol, was traditionally considered to have more warming, stimulating, and carminative properties than fresh ginger. Traditionally, Z. officinale is used in Ayurveda, Siddha, Chinese, Arabian, African, Caribbean, and many other medicinal systems to cure a variety of diseases like pain, nausea, vomiting, asthma, cough, inflammation, dyspepsia, loss of appetite, palpitations, constipation, and indigestion.

Traditional Chinese Medicine (TCM)

In TCM, fresh ginger root (sheng jiang) and dried ginger root (gan jiang) are considered distinct medicines with very different actions. In Traditional Chinese Medicine, ginger, known as "Jiang" (姜), has been utilized for thousands of years due to its potent medicinal properties. TCM philosophy classifies ginger as a warming herb, particularly suitable for conditions characterized by cold or dampness in the body. It is commonly used to treat digestive disorders, colds, arthritis, and various inflammatory conditions. Ginger's actions in TCM include use as a diaphoretic (promotes sweating), antiemetic (reduces vomiting), mucolytic, antitussive, detoxicant, and anti-inflammatory.

Unani Medicine and Other Traditions

Ginger is an ancient remedy of Indian systems of medicine including Ayurveda, Unani, Siddha, and Homoeopathy. It is a plant used in folk medicine from Southeast Asia, in Greco-Roman traditions, in Brazil, Australia, Africa, China, India, and Bangladesh. Zingiber officinale was one of the first oriental spices grown in Europe; it was introduced to Northern Europe by the Romans, who obtained it from Arab traders, and it was one of the most popular spices in the Middle Ages.

In traditional Chinese medicine, ginger has been used since ancient times for the treatment of nausea and headaches; the active pungent constituents activating TRPV1 include gingerols, [6]-shogaol, and the degradation product zingerone.

3. Key Constituents and Established Mechanisms of Action

Structural Basis of Bioactivity

6-Shogaol has been demonstrated to exhibit anticancer, antioxidative, and anti-inflammatory actions more effectively than 6-gingerol due to the presence of an electrophilic Michael acceptor moiety. This α,β-unsaturated carbonyl system (enone) enables 6-shogaol to react with nucleophilic residues — particularly cysteine thiol groups — in a range of proteins involved in inflammation, oxidative stress sensing, and cell survival signaling. This is the unifying structural reason for much of 6-shogaol's broad bioactivity profile.

Anti-Inflammatory Mechanisms

In vivo, 6-shogaol inhibits leukocyte infiltration into inflamed tissue accompanied by reduction of edema swelling. In vitro and in vivo, 6-shogaol reduces inflammatory mediator systems such as COX-2 and iNOS, affects NF-κB and MAPK signaling, and increases levels of cytoprotective enzymes including heme oxygenase-1 (HO-1).

6-Shogaol targets the upstream signal IKK by suppressing IKK-dependent IκBα phosphorylation and degradation, leading to a retardation of p65 nuclear translocation and subsequent inhibition of NF-κB transcriptional activation. This NF-κB inhibition is a major mechanism underlying both its anti-inflammatory and anticancer actions.

In THP-1-derived macrophages, 6-shogaol modulates the NLRP3 inflammasome pathway, reducing IL-1β, IL-18, caspase-1, and gasdermin D activation.

Antioxidant Mechanisms

Ginger and many of its constituents, particularly gingerols and shogaols, are considered potent antioxidants through scavenging various biologically relevant free radicals and modulating a range of redox signaling pathways. The induction of HO-1, which produces the cytoprotective molecules biliverdin and carbon monoxide, is a particularly well-described antioxidant mechanism of 6-shogaol. Analysis of mRNA levels revealed that inhibition of HO-1 suppressed the decreasing effect of 6-shogaol on IL-6, MCP-1, MIP-2, and KC levels in ischemia-reperfusion injury models — findings that strengthen the hypothesis of HO-1 involvement in the anti-inflammatory and protective actions of 6-shogaol.

Antiemetic Mechanisms

Ginger's gingerols and shogaols act on 5-hydroxytryptamine 3 (5-HT₃) receptor antagonism and substance P/neurokinin-1 (NK-1) inhibition as key antiemetic mechanisms. Among ginger constituents, the 5-HT3 receptor-blocking property of 6-shogaol was found to be the best among the analogs tested, followed by 8-shogaol, 8-gingerol, and 10-gingerol. The inhibition of emetic signal transmission activated by 5-HT in vagal afferent neurons by pure compound 6-shogaol was also better than by pure compound 6-gingerol. In vitro studies using HEK293 cells and human colon tissue showed that the 5-HT3R inhibition of 6-gingerol and 6-shogaol was mainly due to restriction of 5-HT-induced Ca²⁺ influx through 5-HT3R.

Using a bioassay for contractile (M)3 receptors (guinea pig ileum), 6-, 8-, and 10-gingerol and 6-shogaol could slightly but significantly depress carbachol-induced contractions. Collectively, these studies provide molecular evidence that ginger antagonizes activation of (M)3 and 5-HT3 receptors, thereby inhibiting afferent inputs to the central nervous system that are stimulated by neurotransmitters such as serotonin released from the gastrointestinal tract.

Additionally, the 6-shogaol constituent can regulate gastrointestinal sensory motor functions via its activities on cholinergic M receptors and serotonergic 5-HT receptors, which may impact the emetic reflex and related symptoms. Research demonstrated that 6-shogaol not only activated but also desensitized gastroesophageal vagal nociceptive C-fiber neurons, with TRPA1 playing an important role in mediating such effects.

Anticancer Mechanisms

The mechanism of action of 6-shogaol as an anticancer agent includes induction of paraptosis, induction of apoptosis, increase in the production of reactive oxygen species (ROS), induction of autophagy, and inhibition of AKT/mTOR signaling. More specifically, the mechanism includes: induction of paraptosis (a non-apoptotic pathway effective in cancer cell death) in breast cancer cells; induction of apoptosis in liver cancer cells via inactivation of Wnt; increase in production of ROS in human colorectal carcinoma cells; induction of autophagy in MCF-7 cancer stem cells; and modulation of Notch or inhibition of AKT/mTOR signaling in lung cancer A549 cells.

In lung and breast cancer cells, 6-shogaol inhibits the phosphorylation of STAT3 and decreases CCL2 expression, preventing the effects of tumor-associated dendritic cells on tumorigenesis and metastasis in vivo and in vitro.

Proteomic analysis revealed that endoplasmic reticulum (ER) stress was accompanied by 6-shogaol-induced apoptosis in hepatocellular carcinoma cells. 6-Shogaol affected ER stress signaling by regulating the unfolded protein response sensor PERK and its downstream target eIF2α.

Neuroprotective Mechanisms

Studies demonstrate that 6-shogaol possesses the ability to mitigate β-amyloid-induced neuroinflammation and cognitive deficits by suppressing the activation of glial cells in murine models. It shields dopaminergic neurons in Parkinson's disease models via anti-neuroinflammation.

Antiplatelet Mechanisms

6-Shogaol has been identified as the best overall antiplatelet lead among gingerol/shogaol derivatives evaluated, though formulation is required to optimize water solubility.

4. Scientific Evidence by Area of Use

4.1 Anti-Inflammatory Activity

In vitro and in vivo, 6-shogaol has been shown to exhibit anticancer, anti-inflammatory, antioxidant, and neuroprotective actions. The anti-inflammatory evidence for 6-shogaol is largely preclinical (cell culture and animal model). Numerous studies focused on the anti-inflammatory potential of 6-shogaol demonstrate the successful inhibition of inflammation. In vivo, 6-shogaol significantly reduced hallmarks of inflammation such as leukocyte infiltration and edema formation, and exhibited neuroprotective effects.

6-Shogaol significantly reduced the adhesion of leukocytes onto LPS-activated human umbilical vein endothelial cells (HUVECs), resulting in significantly reduced transmigration of THP-1 cells through an endothelial cell monolayer. At 30 µM, 6-shogaol blocked the LPS-triggered mRNA and protein expression of cell adhesion molecules. These are in vitro findings.

Evidence strength: Predominantly preclinical (in vitro and animal). No controlled human clinical trials have assessed shogaol's anti-inflammatory effects in isolation from whole ginger extract.

4.2 Antiemetic / Nausea and Vomiting

While shogaol contributes to ginger's antiemetic pharmacology, clinical trials in this area have been conducted with whole ginger or ginger extracts, not isolated shogaol. The mechanistic picture at the molecular level is better established for 6-shogaol as an individual compound.

In vitro studies using HEK293 cells and human colon tissue have demonstrated that 6-gingerol and 6-shogaol effectively inhibit 5-HT-induced calcium influx via 5-HT3 receptors. Ginger's gingerols and shogaols act on cholinergic M3 and serotonergic 5-HT3 receptors to promote gastrointestinal motility.

Both binding studies posited that since binding of ginger compounds to 5-HT receptors occurs at a site other than the orthosteric binding site of competitive 5-HT antagonists, combination therapy with known pharmaceutical 5-HT antagonists might increase antiemetic efficacy.

Evidence strength: The mechanistic evidence for 6-shogaol's contribution to antiemetic activity is in vitro and preclinical. Clinical evidence for antiemetic benefit exists for whole ginger preparations (pregnancy-related nausea, chemotherapy-induced nausea) but cannot be attributed specifically to shogaol in isolation.

4.3 Anticancer / Oncology

6-Shogaol has been characterized as a chemical compound with promising biological activity against various cancers, including leukemia, liver, lung, colon, breast, gastric, skin, kidney, ovarian, and prostate cancer. The cellular processes associated with its molecular anticancer action include the activation of cell death through apoptosis, autophagy, necrosis, and mitotic catastrophe.

In breast cancer, 6-shogaol effectively kills breast cancer stem cells, including monolayers and spheroids, at a dose that is non-toxic to non-cancerous cells. 6-Shogaol-induced cell death in breast cancer cells was suppressed in the presence of chloroquine, and a very low level of apoptosis was exhibited even after prolonged treatment of the compound, suggesting that autophagy is the major mode of cell death induced by 6-shogaol in breast cancer cells.

In colorectal cancer, 6-shogaol at a concentration of 80 µM showed high toxicity to human colon cancer cells SW480 and SW620 (at 95% and 90% reduction, respectively), whereas the viability of normal fibroblasts WI38 was only reduced by 17%.

In leukemia, 6-shogaol selectively induced apoptosis in transformed and primary leukemia cells but not in normal cells. Eukaryotic translation initiation factor 2 alpha (eIF2α), a key regulator in the apoptosis signaling pathway, was significantly affected in both Jurkat and U937 proteome profiles. Results from in vivo studies demonstrated that 6-shogaol administration significantly inhibited the tumor growth of U937 xenografts without causing side effects to the mice.

In non-small cell lung cancer (NSCLC), 6-shogaol inhibits the growth of NSCLC cells both in vitro and in vivo.

Evidence strength: All anticancer evidence for isolated 6-shogaol is preclinical — in vitro (cell culture) or animal (xenograft) models. Despite this knowledge, the mechanism of action of 6-shogaol is not fully understood, and scientific data on its therapeutic dose, safety, and toxicity are not entirely described. No completed human clinical trials on isolated 6-shogaol as an anticancer agent have been published.

4.4 Neuroprotection (Neurodegenerative Disease Models)

6-Shogaol is a comparatively novel anti-Parkinson's remedy with antioxidant and anti-inflammatory characteristics. Studies have determined the role of 6-shogaol in Parkinson's disease (PD) paradigms in rotenone-induced rats. Treatment with 6-shogaol (10 and 20 mg/kg) considerably sustained the elevation of oxidative stress and inflammatory indicators and decreased acetylcholinesterase (AChE) activity and dopamine levels. In histological examination of the brain, 6-shogaol improved the neuronal structure and reduced the degeneration of neurons.

The neuroprotective effects of 6-shogaol were determined using a murine model of middle cerebral artery occlusion (MCAO)-induced brain damage. The daily oral administration of 6-shogaol (5 and 20 mg/kg) resulted in protection against transient focal cerebral ischemia, as indicated by a significant reduction of brain infarct volume and production of malondialdehyde (MDA) and ROS after MCAO induction in murine brains.

Evidence strength: Entirely preclinical (animal models of Parkinson's disease and ischemic stroke). No human clinical trials on isolated 6-shogaol for neurodegenerative conditions have been reported.

4.5 Metabolic Effects (Anti-Obesity, Antidiabetic)

Numerous in vivo studies in rodent models have substantiated the anti-obesity properties of 6-shogaol. Mice subjected to a high-fat diet and treated with 6-shogaol display significant reductions in body weight gain, visceral fat accumulation, hepatic lipid infiltration, and circulating lipid levels. These benefits are often accompanied by improved glucose tolerance, enhanced insulin sensitivity, and normalization of adipokine profiles such as adiponectin and leptin.

Some studies have shown that 6-shogaol produces biological and pharmacological properties such as antioxidant, antilipidemic, antihyperglycemic, anti-inflammatory, antimicrobial, and anticancer activities.

Evidence strength: Preclinical only (rodent diet-induced obesity models). No controlled human trials on isolated 6-shogaol for metabolic outcomes have been reported.

4.6 Renal Protective Effects

In acute kidney injury models, 6-shogaol suppressed plasma creatinine, blood urea nitrogen, and kidney neutrophil gelatinase-associated lipocalin (NGAL). It also decreased renal inflammation, proinflammatory cytokine and chemokine production, neutrophil infiltration, and apoptosis. 6-Shogaol administration after cisplatin treatment improved renal function, suppressed serum creatinine and blood urea nitrogen levels, and mitigated histological kidney damage. Additionally, 6-shogaol suppressed oxidative stress by modulating prooxidant and antioxidant enzymes.

Evidence strength: Preclinical (animal models of chemically induced kidney injury). No human clinical data available for isolated 6-shogaol in renal disease.

4.7 Pain / Analgesic Effects (Chemotherapy-Induced Neuropathy)

In mouse models of oxaliplatin-induced neuropathic pain, intrathecal injections of NAN-190 (5-HT1A receptor antagonist) and MDL-72222 (5-HT3 receptor antagonist), but not ketanserin (5-HT2A receptor antagonist), significantly blocked the analgesic effect of [6]-shogaol (10 mg/kg, i.p.). Furthermore, the gene expression of the serotonin-synthesizing enzyme tryptophan hydroxylase 2 (TPH2) and serotonin levels in the spinal cord and serum were significantly altered after oxaliplatin and [6]-shogaol administration. 6-Shogaol at 10 mg/kg (but not 1 mg/kg) could alleviate the cold and mechanical allodynia induced by oxaliplatin injections.

Evidence strength: Preclinical animal data only. Findings are mechanistically interesting but require translation into human trials.

4.8 Cardiovascular and Endothelial Effects

Ginger has gained interest for its potential to treat various aspects of cardiovascular disease, and in vitro and animal data support anti-inflammatory, antioxidant, antiplatelet, hypotensive, and hypolipidemic effects. However, human trials are less convincing and more investigations are needed. For shogaol specifically, the evidence is primarily from in vitro studies of human endothelial cells and animal models.

5. Body Systems and Health Areas Associated with Shogaol

• Gastrointestinal system — antiemetic activity (5-HT3 antagonism, M3 receptor modulation), gastrointestinal motility, gut inflammatory conditions
• Immune / Inflammatory system — NF-κB inhibition, COX-2 and iNOS suppression, NLRP3 inflammasome modulation, HO-1 induction, leukocyte adhesion reduction
• Nervous system — neuroprotection in Parkinson's and ischemic models, TRPA1 and TRPV1 receptor modulation, analgesic effects in neuropathic pain
• Oncology — apoptosis, autophagy, paraptosis induction in multiple cancer types; AKT/mTOR, Wnt, STAT3, and Notch pathway inhibition
• Metabolic system — anti-obesity, antihyperglycemic, antilipidemic actions in animal models
• Renal system — nephroprotective effects against chemical-induced acute kidney injury in animals
• Cardiovascular system — antioxidant cardioprotection, antiplatelet activity, endothelial protection

6. Pharmacokinetics, Bioavailability, and Dosage

Human Pharmacokinetic Data

A clinical trial examined the pharmacokinetics and tolerability of 6-shogaol (along with 6-, 8-, and 10-gingerol) in healthy human volunteers given ginger at doses from 100 mg to 2.0 g (N=27), with blood samples obtained from 15 minutes to 72 hours after a single oral dose. Participants were allocated in a dose-escalation manner starting with 100 mg, with three participants at each dose except 1.0 g (N=6) and 2.0 g (N=9).

No participant had detectable free 6-shogaol (or gingerols), but 6-shogaol glucuronides were detected. No detectable 6-shogaol sulfates were found except in one participant with detectable 8-gingerol sulfate. This indicates rapid and extensive first-pass conjugation.

The pharmacokinetics and toxicity of 6-shogaol have been studied in animal models and in humans. Studies in rats show 6-shogaol is well absorbed from the gastrointestinal tract (GIT), with most (64%) excretion occurring via the fecal route through biliary excretion. Urinary excretion is on the order of 20%. 6-Shogaol was rapidly and extensively metabolized when given to healthy human subjects; its glucuronic acid conjugates were detected in plasma from 15 minutes to 72 hours post-administration.

Bioavailability Limitations

Low bioavailability alongside poor solubility of 6-shogaol hinders its clinical application, probably due to poor absorption, hydrophobicity, extreme instability, rapid metabolism, and concomitant elimination. To address this, different administration forms, such as micelles carrying 6-shogaol, have been evaluated regarding anticancer properties. According to an oral pharmacokinetic study, micelles loaded with 6-shogaol enhanced delivery efficiency, oral bioavailability, and distribution in the liver. These micelles were endocytosed by a human hepatoma cell line (HepG2), causing stronger inhibition of cell proliferation than free 6-shogaol.

Metabolite Activity

Growth inhibition assays showed that most metabolites of [6]-shogaol had measurable activities against human cancer cells HCT-116 and H-1299. In particular, metabolite M2 greatly retained the biological activities of [6]-shogaol, with an IC₅₀ of 24.43 µM in HCT-116 human colon cancer cells and an IC₅₀ of 25.82 µM in H-1299 human lung cancer cells. Toxicity evaluation of the synthetic metabolites against human normal fibroblast colon cells CCD-18Co and human normal lung cells IMR-90 demonstrated a detoxifying metabolic biotransformation of [6]-shogaol.

Dosages Reported in Preclinical Studies

The following dosages appear in the cited preclinical literature and are reported here for scholarly completeness. These are not human clinical doses.

• 6-Shogaol at 10 and 20 mg/kg was used in rotenone-induced Parkinson's disease rat models.
• Daily oral administration of 6-shogaol at 5 and 20 mg/kg resulted in protection against transient focal cerebral ischemia in murine models.
• 6-Shogaol at 10 mg/kg (i.p.) but not 1 mg/kg alleviated cold and mechanical allodynia induced by oxaliplatin in mice.

Dosages in Human Ginger Pharmacokinetic Studies

The clinical pharmacokinetic trial evaluated 6-shogaol and gingerols and their conjugate metabolites at six dose levels — 100, 250, 500, 1000, 1500, and 2000 mg — administered orally to twenty-seven healthy human volunteers. Ginger and its constituents at doses up to 2.0 g daily have demonstrated very low levels of toxicity and high levels of tolerability in both animals and humans, with only mild gastrointestinal complaints being reported.

7. Safety Considerations and Interactions

General Safety Profile

Ginger has been classified as "generally recognized as safe" (GRAS) by the U.S. Food and Drug Administration (FDA) when used in food amounts. Although ginger is generally considered to be safe, the lack of complete understanding of its mechanisms of action suggests caution in its therapeutic use.

Ginger and its constituents at doses up to 2.0 g daily have demonstrated very low levels of toxicity and high levels of tolerability in both animals and humans, with only mild gastrointestinal complaints being reported. In some people, ginger can have mild side effects such as stomach upset, heartburn, diarrhea, and gas.

Toxicity of Isolated 6-Shogaol at High Concentrations

A high concentration of 6-shogaol induces toxicity in zebrafish embryos, revealed by increased mortality and hatching inhibition. However, no toxicity effects were observed at low concentrations, suggesting a concentration-dependent toxicity profile.

Many in vitro and in vivo studies have confirmed that 6-shogaol exhibits no or little toxic effects on normal cells/tissues at doses that can significantly kill cancer cells, though this selectivity remains to be validated in human trials.

Drug Interactions: Anticoagulants and Antiplatelet Agents

A review of herb-drug interactions identified ginger (among danshen, dong quai, ginkgo, licorice, and turmeric) as contributing to increased bleeding risks due to additive anticoagulant or antiplatelet effects. Caution when taking ginger and other herbal extracts has been suggested because of an apparent association of ginger with reported incidences of increased risk of bleeding following surgery, or if taken with anticoagulant drugs such as warfarin.

However, the evidence is not uniform: the data are not conclusive, and at least one study indicates that ginger has no effect on blood pressure, heart rate, or coagulation parameters and does not interact with anticoagulant drugs such as warfarin. While there has been no direct advisory against the incorporation of ginger in the diets of patients anticoagulated with warfarin, there is a warning from the FDA advising healthcare providers to be cautious in patients on warfarin who also use ginger.

Drug Interactions: Diabetes Medications

Ginger has been studied for its ability to lower blood sugar and improve insulin sensitivity, meaning that concurrent use with antidiabetic agents may alter glycemic control. The bioactive shogaol fraction contributes to this antihyperglycemic potential observed in preclinical studies.

Bioavailability and Unpredictability of Supplemental Forms

Concentrated forms of ginger — supplements, extracts, or oils — contain higher doses of active compounds including gingerols and shogaols. These concentrated forms can sometimes influence how the body absorbs or reacts to prescription medications.

Knowledge Gaps

The mechanism of action of 6-shogaol is not fully understood, and the scientific data on its therapeutic dose, safety, and toxicity are not entirely described. The primary limitation across the field is the absence of well-designed human clinical trials on isolated 6-shogaol. Virtually all pharmacological data derives from in vitro cell culture systems or animal models, and significant translation challenges exist — most notably the compound's poor bioavailability and rapid metabolic conjugation when taken orally by humans.

References

• Wikipedia — Shogaol
• Babu et al. (2015). Gingerols and shogaols: Important nutraceutical principles from ginger. Phytochemistry. PubMed PMID: 26228533
• ScienceDirect Topics — Shogaol Overview
• Ling et al. (2010). 6-Shogaol inhibits breast cancer cell invasion by reducing MMP-9 expression via blockade of NF-κB activation. British Journal of Pharmacology. PubMed PMID: 20718733
• American Chemical Society — Gingerol, Shogaol, and Zingerone (Molecule of the Week)
• Semwal et al. — Benefits of Ginger and Its Constituent 6-Shogaol in Inhibiting Inflammatory Processes (Semantic Scholar PDF)
• Aller et al. (2022). Ginger Constituent 6-Shogaol Inhibits Inflammation- and Angiogenesis-Related Cell Functions in Primary Human Endothelial Cells. Frontiers in Pharmacology.
• Figueroa-González et al. (2024). Review of the anticancer properties of 6-shogaol: Mechanisms of action in cancer cells and future research opportunities. Food Science & Nutrition. PMC11266911
• Attallah et al. (2025). The therapeutic potential of naturally occurring 6-shogaol: an updated comprehensive review. Inflammopharmacology.
• Ballester et al. (2021). Benefits of Ginger and Its Constituent 6-Shogaol in Inhibiting Inflammatory Processes. International Journal of Molecular Sciences. PMC8232759
• Ahmad et al. (2024). 6-Shogaol Abrogates Parkinson's Disease in Rotenone-Induced Rodents: Based on In Silico Study and Inhibiting TNF-α/NF-κB/IL-1β/MAO-B. PMC11510247
• Medicinal Plants for Chemotherapy-Induced Nausea and Vomiting: A Systematic Review. PMC12325115
• The Antiemetic Mechanisms of Gingerols against Chemotherapy-Induced Nausea and Vomiting. PMC8893993
• Rudd et al. (2016). The involvement of TRPV1 in emesis and anti-emesis. Experimental Brain Research. PMC4843889
• Thomson et al. (2014). The Effectiveness of Ginger in the Prevention of Nausea and Vomiting during Pregnancy and Chemotherapy. Integrative Medicine Insights. PMC4818021
• Involvement of the Spinal Serotonergic System in the Analgesic Effect of [6]-Shogaol in Oxaliplatin-Induced Neuropathic Pain in Mice. PMC10610466
• Ginger Constituent 6-Shogaol Attenuates Vincristine-Induced Activation of Mouse Gastroesophageal Vagal Afferent C-Fibers. PMC9654566
• Zick et al. (2010). Pharmacokinetics of 6-, 8-, 10-Gingerols and 6-Shogaol and Conjugate Metabolites in Healthy Human Subjects. PMC2676573
• Zhu et al. (2013). Metabolites of Ginger Component [6]-Shogaol Remain Bioactive in Cancer Cells and Have Low Toxicity in Normal Cells. PMC3559867
• Is 6-Shogaol an Effective Phytochemical for Patients With Lower-risk Myelodysplastic Syndrome? A Narrative Review. PMC8728773
• Zhang et al. (2019). Enhanced Oral Bioavailability, Anti-Tumor Activity and Hepatoprotective Effect of 6-Shogaol Loaded in Novel Micelles. PMC6470752
• Anticancer perspective of 6-shogaol: anticancer properties, mechanism of action, synergism and delivery system. PMC10594701
• 6-Shogaol induces apoptosis in human leukemia cells through a process involving caspase-mediated cleavage of eIF2α. PMC4176122
• Hu et al. (2012). 6-Shogaol Induces Apoptosis in Human Hepatocellular Carcinoma Cells and Exhibits Anti-Tumor Activity In Vivo through Endoplasmic Reticulum Stress. PMC3387266
• Ray et al. (2015). 6-Shogaol Inhibits Breast Cancer Cells and Stem Cell-Like Spheroids by Modulation of Notch Signaling Pathway and Induction of Autophagic Cell Death. PMC4565635
• Bode AM, Dong Z. The Amazing and Mighty Ginger. In: Herbal Medicine: Biomolecular and Clinical Aspects. NIH/NCBI Bookshelf. NBK92775
• Effects of Oral Ginger Supplementation on the INR. PMC6594244
• A Review of Potential Harmful Interactions between Anticoagulant/Antiplatelet Agents and Chinese Herbal Medicines. PMC3650066
• Preparation and Evaluation of 6-Gingerol Derivatives as Novel Antioxidants and Antiplatelet Agents. PMC10045534
• Aller et al. (2022). Ginger Constituent 6-Shogaol Inhibits Inflammation- and Angiogenesis-Related Cell Functions in Primary Human Endothelial Cells. PMC8914105
• NIH National Center for Complementary and Integrative Health (NCCIH) — Complementary Health Approaches for Travelers (Ginger section)