Here’s the short answer: I wouldn’t give it to them. None of my sources gives a safe amount for a backyard flock, and the one safety level I found for laying hens is tiny. Four of the five chicken trials I read fed only its oil, weighed into the feed. Europe’s food safety agency, EFSA, has a feed panel that looked at that oil. It considered the oil of low concern for laying hens at just 0.6 mg per kg of complete feed. That’s because of a compound in it called estragole. And a pod from the store could be Japanese star anise, which is toxic. According to the FDA, Japanese star anise “in its dried or processed form cannot be distinguished from Chinese star anise through visual examination”. So my call is to keep star anise in your kitchen and out of your coop.
I rewrote this page from 14 sources, all listed at the bottom. At its core is the FDA’s 2003 advisory on star anise teas, which I read through the Internet Archive’s copy. A 2004 paper in Pediatrics and a 2002 report from the Netherlands describe the poisonings. Two papers from the University of Mississippi show how a lab tells the two kinds apart. For the feed safety levels I used the 2023 opinion of EFSA’s FEEDAP Panel on star anise oil in feed for all animal species. A 2023 review in Molecules covers the tree and what’s in the fruit. Five chicken trials, all with authors at Shandong Agricultural University in China, fed star anise or its oil. I read four of them as PubMed abstracts and the 2020 broiler trial in full. Colorado State University Extension gave me the treat rules, and I looked for star anise in USDA’s FoodData Central.
A word on the photos. Yana Gorbunova’s star anise in front of a cinnamon stick went up on Unsplash in December 2020. Walter Grassroot shot the loose pods on white in January 2020, and the photo is on Wikimedia Commons. That file’s name is Chinese for star anise from Nanning, in Guangxi, and Commons files it under Illicium verum. Daderot’s tree is from September 2015. Commons files it under Illicium verum too, as a botanical specimen in the Chengdu Botanical Garden in China. Isasza’s hen is on Flickr, taken in February 2017. Its page says she is “A hen removed from the miserable existence of an egg production plant”. Tamsin Cooper’s hen settled in straw is on Flickr too, from La Chiffetière in Normandy in December 2018. The spinach is from Shutter Sphere Collective, on Unsplash, from November 2019. None of the star anise photos says it is Japanese star anise.
The old page opened with a story I can’t back up. Henrietta the Buff Orpington and her pod in the corner are gone. So is the soup pot from “making soup stock the other day”, and so is “little Becky the Brahma”. I cut the tree-growing part too, starting with the planting “right here on the farm”. Out went the seeds that sprouted “Within a couple weeks”, and so did the wait of “3-5 years to reach maturity”. I also cut “Ever since I first started offering star anise to my flock a few years ago”. I can’t show you any of that happened.
Most of the facts didn’t hold up either. Star anise was “packed full of important minerals”, the old page said, and it named four. I searched USDA’s FoodData Central for star anise, and the only spice it turned up was anise seed, which is a different plant. So that line is out, and so is “high in antioxidants that support the immune system”. I found no source for the minerals. For antioxidants, the 2018 hen trial below found the oil, weighed into feed, raised the hens’ antioxidant markers, but its abstract says nothing about their immune systems. The old page also said the oils “have been shown to improve digestion and gut health in poultry”. Yes, the trials below found better nutrient use in hens and taller gut villi in broilers. But that was on measured doses of the oil, or of ground star anise at 5 g per kg, mixed into feed, not a pod in your run. “Experts suggest starting with 1/8 to 1/4 teaspoon per 3-5 birds” named no expert. None of my sources gives a treat dose of whole star anise, so that’s out. So is “toxic to liver function over many months”. None of my sources says that of star anise in chickens. EFSA’s two reference doses do come from rodents fed methyleugenol, a related compound. One is liver tumors in rats, used for long-lived animals like laying hens. The other is non-cancer damage to the liver and stomach in a 90-day mouse study, used for meat animals. More on that below. I didn’t check “700psi” or the “2 hour digestion cycle” this time, so those are gone too. And the old height of “15-30 feet tall” was off. Per the 2023 review it’s 10 to 15 meters, or about 33 to 49 feet by my math.
The short version.
- None of my sources gives a safe amount of star anise for a backyard flock, and our food checker doesn’t rate it. My call: skip it as a treat.
- A store pod could be Japanese star anise. It’s toxic, and the FDA says you can’t tell it from the spice by looking.
- Star anise teas were tied to illnesses in about 40 people by 2003, about 15 of them infants (FDA). In 2001, one herbal tea sent 22 people to the hospital in the Netherlands.
- Chicken trials fed star anise oil at 200 to 600 mg per kg of feed, or ground star anise at 5 g per kg to broilers.
- EFSA’s feed panel put the oil’s low-concern level for laying hens at 0.6 mg per kg of complete feed, because of estragole. By my math, the trials’ lowest oil dose is about 333 times that.
- Treats should stay at no more than 10% of the daily diet (Colorado State).
A Store Pod Could Be Japanese Star Anise, and You Can’t Tell by Looking
You’ve got two plants to know. Chinese star anise, Illicium verum, is the spice. Japanese star anise, Illicium anisatum, is the trouble. Its fruits “are well known as neurotoxic and contain the convulsants anisatin and neoanisatin”, says the 2023 review.
In 2003 the FDA put out an advisory after brewed star anise teas were tied to illnesses in about 40 people, about 15 of them infants. They ranged from seizures to vomiting and jitteriness. At the time, the FDA hadn’t pinned down which kind of star anise was in those teas. But it was concerned that commonly available Chinese star anise “may contain Japanese star anise (Illicium anisatum), which has long been recognized as toxic in many countries”. That kind, it said, “should be used for decorative purposes only”. It also said “Japanese star anise in its dried or processed form cannot be distinguished from Chinese star anise through visual examination”.
So the FDA treats the two kinds differently. “FDA considers Chinese star anise to be GRAS when used as a spice or flavoring; Japanese star anise is not GRAS.” GRAS means generally recognized as safe. Everyone in those reports, infants too, “recovered without complications”, the advisory adds.
Doctors had seen it too. A 2004 paper in Pediatrics, from Miami Children’s Hospital, reported 7 infants with neurologic reactions after star anise tea given at home. Its authors wrote “we have found evidence that Chinese star anise has been contaminated with Japanese star anise”. Their advice was plain: “Star anise tea should no longer be administered to infants”. In the Netherlands in 2001, 63 people fell ill 2 to 4 hours after drinking one herbal tea. Twenty-two went to the hospital, 16 of them with seizures. Japanese star anise “may have been inadvertently mixed into the herbal tea”, that report says. NMR analysis of the tea confirmed anisatin, which it calls “a non-competitive GABA-antagonist”. After supportive treatment, the patients went home in good health.
Telling the two apart takes a lab. In 2005, a University of Mississippi team developed a way to detect Japanese star anise mixed into powdered Chinese star anise, with fluorescent microscopy and gas chromatography. In 2009, a team from the same center developed a DNA test that tells them apart in powdered samples. My read: if it takes a microscope or a DNA test, there’s no sorting pods on your kitchen counter. None of these cases involved chickens, and my PubMed search found no study of Japanese star anise in poultry. So I can’t tell you what a bad pod does to a hen, and that’s one more reason I’d skip it.
The Chicken Trials I Read Mostly Fed Star Anise Oil, Weighed Into the Feed
So what about the studies? This is what five chicken trials fed, to which birds, and for how long.
- Laying hens, 2018 (Poultry Science). 864 Hy-Line Brown hens, 26 weeks old, got star anise oil at 0, 200, 400 or 600 mg per kg of feed for 56 days. Over the whole trial, egg weight, egg mass, laying rate and feed conversion were about the same. Antioxidant markers rose with the dose, in the hens’ blood and liver and in their yolks.
- Laying hens, 2019 (Animal Science Journal). 96 Hy-Line Brown hens, 29 weeks old, got the same four levels for 14 days. They made better use of protein and some amino acids, and the authors say “the efficacy is best at 400 mg/kg”.
- Leghorn roosters, 2020 (Poultry Science). 512 male White Leghorns, 30 weeks old, got the oil at 0 to 600 mg per kg, with half of them dosed with E. coli. After a week to settle in, the trial ran 3 weeks. Their antioxidant enzymes went up on the oil, and the authors put the best dose against E. coli at 400 mg/kg.
- Broilers, 2020 (Poultry Science). 384 meat chickens ate for 42 days on one of four diets. One was plain. One had 5 g per kg of ground star anise, and one had 0.22 g per kg of its oil. The last had 5 g per kg of the powder left after the oil was steam-distilled out. That star anise was “purchased from a local market”. Birds on star anise or the oil finished heavier than the plain-diet birds, but carcass yield was about the same.
- Broilers, 2021 (Animal Science Journal). 192 Arbor Acres male broilers, from 28 days old, got the oil at 0 to 600 mg per kg in feeds at three energy levels. On the oil, they made better use of their nutrients.
In 2018, the authors concluded the oil “enhanced laying performance and overall antioxidant status of laying hens in a dose-dependent manner”. My read is that the laying part is thin. Over the full 56 days the hens laid about the same. Egg mass and egg weight only trended up, and only over days 1 to 28, where the abstract says more oil “tended to improve (P < 0.10)” them. Feed intake did differ over the whole 56 days, though the abstract doesn’t say which way. A trend isn’t a firm result.
Keep in mind what these were. They were commercial birds on measured feed, and the four trials that give a length ran 14 to 56 days. Three of the five were on broilers or roosters, so I wouldn’t stretch those to a laying hen in your run. From what I read, none of the five set out to test the estragole question in the next section. They measured laying and nutrient use, plus antioxidants and carcass traits. So a good result in a trial doesn’t get you to tossing pods in your run.
EFSA’s Low-Concern Level for Laying Hens Is 0.6 mg per kg of Feed
Here’s the number that settled it for me. In 2023, EFSA’s FEEDAP Panel looked at star anise oil as a flavoring in feed and water for all animal species. Its worry is estragole. Batches it looked at held 2.67% to 4.09% estragole. For the people who handle the oil, the opinion puts it plainly: “Due to the high concentration of estragole (≥ 1%), the additive is classified as suspected of causing genetic defects and of causing cancer and should be handled accordingly.”
For the animals that eat it, the applicant, FEFANA asbl, proposed much lower levels for long-lived and breeding animals than for meat animals. Working from margins of exposure, the panel found them of low concern, and of no concern for meat animals. For laying hens and rabbits, it considered the oil “of low concern” at 0.6 mg per kg of complete feed. For chickens raised for meat, it’s 18.5 mg per kg, and for meat turkeys it’s 24.8. What changes is how long the animal lives. For long-lived and breeding animals, the panel wants the estragole they eat to stay more than 10,000 times below a reference dose from cancer studies in rodents fed methyleugenol, a compound in the same group. For meat animals, which don’t live long, it wants intake more than 100 times below a different dose, the no-harm level for non-cancer damage in a 90-day mouse study. Its own math for a laying hen uses a 2 kg bird eating 106 g of feed a day, counted dry.
Now set that beside the trials. By my math, 200 mg per kg is about 333 times EFSA’s 0.6, and 600 mg per kg is 1,000 times. EFSA wasn’t judging those trials, and it gave no number for a whole pod. But it’s the only safety level for laying hens I found, and the trials’ lowest oil dose is hundreds of times above it. On water, the panel says use in drinking water “should not exceed the daily amount that is considered of low concern/no concern when consumed via feed alone”. My read: steeping pods in your waterer doesn’t get around it.
One more line from the opinion stuck with me. EFSA didn’t ask anyone to show the oil does something for animals. Since star anise is a known flavor for food, “no further demonstration of efficacy was necessary”. In feed, its job is flavor.
What’s in a Pod, and Why the Mineral Claims Are Out
Look closely at one and you’ll see why it’s called a star. It “is cogwheel shaped and consists of an average of eight pods”, according to the 2023 review. EFSA describes a ring of reddish-brown sections, each with a single seed, usually picked just before ripening. Its oil is mostly trans-anethole, more than 80% of it per the review. EFSA says its smell and taste closely resemble “true anise fruit”, which is a different plant, Pimpinella anisum.
Even the right species holds compounds that proved toxic to mice. In 1996, three compounds called veranisatins were taken from star anise, the review reports. They “were found to have convulsive effects and lethal toxicity at an oral dose of 3 mg/kg in mice”. Anisatin did the same at 1 mg/kg. Those were purified compounds given to mice, not a pod in a run. My read is only that the spice isn’t a plain food. About the poisonings in infants, the review notes that in 2004 it was speculated “the cause could be an excess of anise, contaminated anise, or a combination of both”.
As for minerals, I couldn’t find star anise in FoodData Central, so the old page’s mineral list is gone. If you want to know what’s in your hens’ feed, read the label on the bag from the feed store.
The Tree Is an Evergreen From China and Vietnam
Star anise grows on a tree. EFSA calls Illicium verum “an evergreen tree belonging to the Schisandraceae family, native to Vietnam and China.” Per the review, “It is a 10–15 m tall arbor plant.” That’s about 33 to 49 feet, by my math. It says the tree “blooms twice a year”, once in March to May with the high yields, and again in August to October. And it says star anise “is mainly produced in China and Vietnam”.
The old page grew six of these from seed and planted them under peach trees, and I can’t back that story up. Growing it is beyond this page. If you’ve got one in a pot, my call is the same: the pods stay out of your run.
What Our Food Checker Says, and What I’d Give Instead
Our can-chickens-eat-it checker answers “Not rated here” for star anise. None of the official sources it uses rules on it, “so it will not guess.” It gives the same answer for anise seed and fennel. Its last word is mine too: “there is always another treat”. It’s the same call I made on star fruit, which carries a nerve toxin of its own, caramboxin.
So what goes in your treat pile? Colorado State keeps it simple. It says to “Consider leafy greens, vegetable peelings, discards, and bread products.” It adds “Make sure they are not salty or have citrus or are moldy.” It also says “Treats should make up no more than 10% of their daily diet.” And “Do not feed more than can be consumed in 5 – 10 minutes”, so the leftovers don’t draw nuisance animals. My read is that a raccoon counts.
If star anise went into your soup pot, pick the pods out before any scraps go to your hens. Our chicken broth post covers the salt and the onion, two more things to keep out of their share. And if a hen gets into your spice rack and acts off after, call a vet who sees poultry.
Sources
- U.S. Food and Drug Administration: FDA Issues Advisory on Star Anise Teas, P03-67 (September 10, 2003), the Internet Archive’s copy.
- Ize-Ludlow and colleagues, Pediatrics 2004: Neurotoxicities in infants seen with the consumption of star anise tea (PubMed abstract).
- Johanns and colleagues, Nederlands Tijdschrift voor Geneeskunde 2002: an epidemic of epileptic seizures after consumption of herbal tea (PubMed abstract, in English).
- Joshi and colleagues, Journal of AOAC International 2005: identifying Illicium verum and its adulterant Illicium anisatum (PubMed abstract).
- Techen and colleagues, Planta Medica 2009: Detection of Illicium anisatum as adulterant of Illicium verum (PubMed abstract).
- EFSA FEEDAP Panel, EFSA Journal 2023: Safety and efficacy of a feed additive consisting of an essential oil derived from the fruit of Illicium verum (star anise oil) for use in all animal species.
- Zou and colleagues, Molecules 2023: A Comprehensive Review of the Pharmacology, Chemistry, Traditional Uses and Quality Control of Star Anise.
- Yu and colleagues, Poultry Science 2018: star anise essential oil and the laying performance of laying hens (PubMed abstract).
- Yu and colleagues, Animal Science Journal 2019: star anise essential oil and nutrient use in laying hens (PubMed abstract).
- Ding and colleagues, Poultry Science 2020: star anise oil in chickens during an E. coli challenge (PubMed abstract).
- Ding and colleagues, Poultry Science 2020: star anise and its extractions in broiler chickens.
- Yu and colleagues, Animal Science Journal 2021: star anise essential oil at three dietary energy levels in broilers (PubMed abstract).
- Colorado State University Extension: Raising Poultry the Organic Way, Disease Control and Feeding.
- USDA Agricultural Research Service: FoodData Central (searched for star anise).
Sources checked November 3, 2026. I read the Pediatrics paper, the Dutch report, the two lab papers and four of the five trials as PubMed abstracts, not full papers. The 333 and 1,000 times, and the 33 to 49 feet, are my math. That the 2018 laying result is thin, and that the broiler and rooster trials don’t reach a laying hen, are my read. Skipping star anise as a treat is my call. We aren’t vets. If a hen eats something you’re not sure of and acts sick, call a vet who sees poultry.
Related read: How to Raise Chickens for Eggs — Instant PDF download. Secure checkout by Stripe