Benefits
Traditional use as a digestive and carminative spice
Chinese star anise is used around the world to flavor cooking and is brewed as a warm tea. In traditional practice the fruit is taken to ease gas and digestive discomfort and to warm the body, and European pharmacopoeia material lists spasmolytic and expectorant activity for the fruit and its oil. These are traditional and laboratory descriptions, not results from controlled trials in people.
Industrial source of shikimic acid, a drug manufacturing precursor
Star anise is the main commercial source of shikimic acid, the chemical that pharmaceutical factories use as a raw starting material to synthesize the prescription antiviral oseltamivir. Turning shikimic acid into the finished medicine takes many chemical steps. The spice is not itself an antiviral drug, and consuming it does not deliver oseltamivir or any antiviral effect in the body.
Antioxidant and antimicrobial activity in laboratory tests
In laboratory assays, star anise essential oil and extracts, which are rich in trans-anethole, show antioxidant, antibacterial and antifungal activity against isolated microbes and in chemical tests. This is test-tube activity on isolated organisms and samples. It has not been shown to produce these effects in people and is not evidence that the spice fights infection in the body.
Food use tied to correct Chinese star anise identity
The fruit eaten as a spice is Chinese star anise, Illicium verum. Its close relative Japanese star anise, Illicium anisatum, looks similar but carries neurotoxic sesquiterpene compounds and is not food safe. Using only clearly identified, properly labeled Chinese star anise from a reputable source is central to safe culinary use. This is a sourcing and safety point rather than a health benefit.
Mechanism of action
Trans-anethole, the main aromatic oil compound
The fruit yields an essential oil in which trans-anethole is the dominant constituent, responsible for the sweet, licorice-like aroma and flavor. In laboratory studies this oil shows smooth-muscle relaxing (spasmolytic) and antimicrobial activity, which is the basis for the traditional culinary and digestive use of the spice.
Shikimic acid as a chemical building block, not an active drug
Shikimic acid is an intermediate of the plant shikimate pathway and accumulates in the fruit, which is why star anise is harvested as a commercial source of it. Chemists extract the acid and run a multi-step synthesis to build oseltamivir. Eaten in the spice, shikimic acid has no established antiviral action of its own; it is a raw material, not a medicine.
Neurotoxic sesquiterpenes in Japanese star anise
Japanese star anise and some other Illicium species contain neurotoxic sesquiterpene compounds that can affect the nervous system and provoke seizures and gastrointestinal upset. Chinese star anise is low in these compounds, so the botanical identity and purity of the product are what determine whether it is safe to consume.
Clinical trials
Case series reporting adverse neurologic reactions in infants after home administration of star anise tea, with chemical analysis showing Chinese star anise contaminated with Japanese star anise (Ize-Ludlow et al. 2004, Pediatrics).
7 infants given home-prepared star anise tea, commonly used as a remedy for colic.
The infants developed adverse neurologic reactions after drinking star anise tea, and testing found Chinese star anise contaminated with toxic Japanese star anise. The authors concluded that star anise tea should no longer be given to infants because of its potential danger in this group, and called for stricter regulation of star anise imports.
Epidemiological investigation and matched case-control study of infants under 3 months with gastrointestinal and neurological symptoms after star anise infusion used as a carminative, with laboratory testing of the products (Garzo Fernandez et al. 2002, An Esp Pediatr).
23 infants with symptoms were studied; 18 cases and 36 controls entered the case-control analysis.
Symptoms were irritability, abnormal movements, vomiting and nystagmus. Consuming anise infusion was strongly associated with symptoms (Mantel-Haenszel odds ratio 18.0), with a dose-response relationship, and laboratory analysis found Illicium verum contaminated with Illicium anisatum. The authors advised against anise infusions for infants and recommended destroying the contaminated products.
Single case report of a previously healthy neonate evaluated for seizures and other symptoms after ingesting star anise tea given for colic (Donner et al. 2021, R I Med J).
A previously healthy 2-week-old boy given star anise tea for colic.
The infant was seen in the emergency department with abnormal movements, irritability and vomiting after ingesting star anise tea. The report notes that Chinese star anise is often contaminated with Japanese star anise or used in high doses, producing neurotoxicity and gastrointestinal disturbance, and reinforces that the tea should not be used in infants.
Case report of intoxication with Japanese star anise presenting as an epileptic seizure after drinking a herbal tea (Biessels et al. 2002, Ned Tijdschr Geneeskd).
An adult who had an epileptic seizure after drinking a cup of star anise tea.
The seizure was attributed to intoxication with toxic Japanese star anise (Illicium anisatum). The case accompanied a report of a cluster of seizures after consumption of a herbal tea, illustrating that the toxic look-alike species can trigger seizures in adults as well as infants when it reaches the consumer in place of the food-grade spice.
Case series describing star anise poisoning in infants, framed as a caution against the traditional use of the spice as an infant remedy (Minodier et al. 2003, Arch Pediatr).
Infants given star anise preparations.
The report describes poisoning in infants given star anise, consistent with the neurological and gastrointestinal toxicity reported elsewhere and with contamination by toxic Japanese star anise. It adds to the body of case reports advising that star anise preparations should not be given to infants.