Coriander

What is Coriander?

Coriander seed essential oil is 60 to 80 percent linalool, and leaf essential oil from the same plant measured 0.1 to 0.5 percent linalool across four cultivars, which is why the two smell nothing alike and why a finding on one does not transfer to the other. The plant is Coriandrum sativum L., an annual Apiaceae herb 20 to 70 cm tall with a taproot, white to pale pink flowers in compound umbels, and a dry schizocarp fruit that splits into two mericarps. In the United States the fresh leaf is cilantro and the dried fruit is coriander. In Britain both are coriander. Almost every sourcing error in this category starts there.

The divergence is not subtle. Kumar and colleagues steam distilled the fresh leaves of four cultivars (Desi, Peshawari, Irani and Hybrid) in 2022 and found aldehydes made up more than 70 percent of every oil, with (E)-2-decenal running 15.7 to 25.1 percent and decanal 18.4 percent in the Desi line. Linalool, the molecule that defines the seed, appeared at 0.1 to 0.5 percent. Fan and Sokorai at the USDA Eastern Regional Research Center reported in 2002 that decanal and (E)-2-decenal together accounted for more than 80 percent of identified volatiles in fresh cilantro leaf.

Common Names

• Coriander, coriander seed, coriander fruit, Coriandri fructus

• Cilantro, Chinese parsley, Mexican parsley (all meaning the fresh leaf)

• Dhania (Hindi), kothimeera (Telugu), kottamalli (Tamil), kottambari (Kannada), kusthumbari (Sanskrit)

• Coriandri aetheroleum, the pharmacopeial Latin for the distilled fruit oil

Primary Active Compounds

• Linalool, a monoterpene alcohol, 60 to 80 percent of the fruit's volatile oil and the reason the seed smells sweet and citrus-like

• (E)-2-decenal, decanal, (E)-2-dodecenal and (E)-2-tetradecenal, the aliphatic aldehydes that dominate leaf oil and give cilantro its polarizing odor

• Petroselinic acid, 60 to 75 percent of the fixed oil pressed from the seed, per the European specification

• Geranyl acetate, camphor, gamma-terpinene and p-cymene, each a single-digit percentage of fruit oil

• Umbelliferone and bergapten, coumarins present only in traces

Key Note

Coriander fruit oil yields vary from 0.18 to 1.40 percent by volume on weight, and the linalool fraction within that oil swings by geography: 60 to 70 percent across 19 Iranian accessions, 73.1 percent in a European variety, 82.9 percent in an Argentinean one. Leaf yields are far lower and much less consistent between studies, 0.027 to 0.042 percent w/w from fresh leaves in the Kumar cultivar trial against 0.45 percent reported by Chung. Whichever leaf figure you take, the oil you get is chemically unrelated to the seed's. A supplement that says only "coriander" has told you almost nothing.

Coriander is a spice with a narrow, real set of effects and one enormous marketing claim attached to it that no human trial supports.

Primary Functions & Benefits

Coriander is a carminative and a mild antispasmodic, and since 2008 it has accumulated a small topical dermatology file. Those are the honest categories.

What regulators have actually said

Germany's Commission E approved Coriandrum sativum for dyspeptic complaints and loss of appetite. That is the full indication, and it is a traditional-use approval resting on long usage rather than on controlled trials.

The European Medicines Agency's Committee on Herbal Medicinal Products has not adopted a monograph for coriander fruit or coriander oil. Where caraway and fennel each have EU herbal monographs with specified posologies, coriander has none. Coriander does not appear in the Committee's May 2021 inventory of herbal substances for assessment either, so the gap is not a monograph in progress.

The one firm European regulatory act on coriander is a food law instrument, not a medicines one. Commission Implementing Decision 2014/155/EU of 19 March 2014 authorized coriander seed oil as a novel food ingredient on an application by Nestec Ltd of Vevey, restricted it to food supplements at no more than 600 mg per day, and required the label to read "coriander seed oil." That decision concerns the pressed fixed oil rich in petroselinic acid, not the distilled essential oil.

Topical antimicrobial activity

Casetti and colleagues tested fruit essential oil against clinical isolates in 2011 and reported mean minimum inhibitory concentrations of 0.04 percent v/v against Streptococcus pyogenes and 0.25 percent v/v against methicillin resistant Staphylococcus aureus. Patch testing a cream and a lotion at 0.5 and 1.0 percent in 40 healthy volunteers produced no measurable irritation.

What coriander does not do

It does not remove metals from a human body in any way that has been measured. It does not measurably change the salivary microbiome: Kazarina and colleagues randomized 38 periodontitis patients to a coriander essential oil mouthwash, 0.12 percent chlorhexidine, or water for 14 days, sequenced 54 saliva libraries from the 27 who gave paired samples, and found no detectable species-level difference between coriander oil and water (q = 0.413), while chlorhexidine shifted both Bray-Curtis distance (q = 0.020) and Simpson diversity (q = 0.014). The authors stated plainly that no clinical benefit can be inferred from their null.

Forms & Standardization

Five unrelated materials are sold under one word.

Whole fruit (the spice)

The dried schizocarp, 3 to 5 mm across, pale brown, with longitudinal ridges and two mericarps that separate when crushed. Volatile oil content across the literature runs 0.18 to 1.40 percent v/w, with most commercial lots at the low end. Whole fruit held dark and closed keeps that oil for years.

Ground fruit

The same material with its oil canals ruptured. Grinding is also where contamination enters, with a number in the quality section.

Coriander fruit essential oil (steam distilled)

Covered by ISO 3516:1997, "Oil of coriander fruits (Coriandrum sativum L.)," second edition published July 1997, superseding ISO 3516:1980 and last reviewed and confirmed current in 2023. Linalool is the marker, and the number moves with origin and with extraction. Supercritical carbon dioxide gave the highest reported yield at 5.8 percent of seed weight, but a carbon dioxide extract pulls fixed oil along with the volatiles and is not the same material as a distillate. In a separate comparison, hydrodistillation gave 0.2 percent and microwave assisted hydrodistillation 0.1 percent. Solvent choice shifts composition, not just quantity: Soxhlet extraction returned more camphor, geranyl acetate and terpinene and less geraniol and linalool than steam distillation of the same material. Subcritical water extraction above 170 degrees Celsius converts linalool to linalool oxide, so a high-temperature process can destroy the very marker the label sells. Ripeness matters too. Unripe fruits carry higher total oil and higher linalool than mature ones, and immature fruit oil also contains geranyl acetate, nerol and neral that the mature fruit has largely lost.

Coriander leaf essential oil (cilantro oil)

A different product with a different smell, often described as unpleasant because of the aldehydes. Yields from fresh leaves ran 0.027 to 0.042 percent w/w and densities 0.73 to 0.79 g/mL in the Kumar four-cultivar study. A separate measurement by Chung reported 0.45 percent from leaf and 0.20 percent from stem, a tenfold spread that tells you how much harvest stage and method drive the number. Eyres and colleagues at the University of Otago found (E)-2-decen-1-ol was the single most abundant compound in C. sativum leaf oil at 26.0 percent of total ion chromatogram area yet contributed only 0.39 percent of total odor activity, with Z-2-decenal and a dodecenal cluster doing the actual smelling. Abundance and activity are not the same measurement.

Coriander seed oil (the pressed fixed oil)

Not an essential oil at all. This is the triglyceride oil from the seed, and it is the one material with a legally binding European specification. Decision 2014/155/EU sets petroselinic acid at 60 to 75 percent, linoleic acid 12 to 19 percent, oleic acid 8 to 15 percent, trans fatty acids at most 1 percent, acid value at most 0.6 mg KOH per gram, peroxide value at most 5 milliequivalents per kilogram and unsaponifiable matter at most 15 g/kg, with a ceiling of 600 mg per day in supplements. When Ovalie Innovation of France applied in March 2017 for substantial equivalence, the Food Safety Authority of Ireland allowed a wider acid value of 2.5 mg KOH per gram and a wider iodine value to 110 units against the comparator's 88 to 102. Note the direction of those: Ovalie's figures are maxima where the comparator's iodine value is a range of 88 to 102, and a higher maximum is a looser specification rather than a better oil. The FSAI opinion also recorded stated stability of 18 months stored dry, dark and at or below 20 degrees Celsius, because petroselinic acid oxidizes easily.

Leaf glycerite and leaf capsules

The form actually sold for metal claims. The Source Naturals Cilantro Metal Detox liquid, NIH Dietary Supplement Label Database record 185327, declares organic cilantro 500 mg and organic chlorella 250 mg per 2.5 mL serving, three servings daily. The current retail label restates the cilantro as an organic leaf extract at a 1:3 dry herb strength ratio, equivalent to 500 mg of dry herb, in vegetable glycerin and deionized water. No marker compound. Nothing on that label can be verified for potency because nothing on it is quantified beyond raw plant weight.

Homeopathic mother tincture

The French Pharmacopoeia 2003 monograph specifies a tincture of the dried fruit in 65 percent v/v ethanol, finished ethanol 60 to 70 percent v/v, minimum dry residue 0.4 percent m/m. Linalool appears in it only as a thin layer chromatography reference marker, not as an assayed content.

Which form did the human trials use? The migraine trial used a fruit syrup, the dyspepsia trial a 500 mg two-herb capsule, the dermatology trials fruit essential oil at 0.5 and 1.0 percent in a lipolotion and 6 percent in an ointment base. None of them used a leaf glycerite.

Food Sources

Coriander is food twice over, and the two foods have almost nothing in common nutritionally.

Dried fruit, per 100 g (USDA FoodData Central 170922)

298 kcal, 12.4 g protein, 17.8 g fat, 41.9 g dietary fiber, 709 mg calcium, 16.3 mg iron, 330 mg magnesium, 1,267 mg potassium, 1.90 mg manganese, 21.0 mg vitamin C.

Those look impressive until you divide by the serving. A level teaspoon of ground coriander is about 1.8 g, delivering 12.8 mg calcium, 0.29 mg iron, 5.9 mg magnesium and 0.75 g fiber. Nobody eats 100 g of coriander seed, so the mineral column is a unit artifact and any label quoting it is quoting a number no intake reaches.

Fresh leaf, per 100 g

23 kcal, 92.2 g water, and 310 micrograms of vitamin K1 (USDA FoodData Central 169997). That last figure is the only nutritionally consequential number in coriander, and it matters for one reason covered under interactions. A cup of chopped cilantro weighs roughly 16 g and carries about 50 micrograms of vitamin K1. A restaurant garnish of 4 g carries about 12 micrograms.

What processing does

Fan and Sokorai irradiated fresh cilantro at 0, 1, 2 and 3 kGy and stored it at 3 degrees Celsius for 14 days. Aldehyde content peaked at day 3 and declined afterward regardless of treatment. Linalool, dodecanal and (E)-2-dodecenal were significantly lower in irradiated samples by day 14, but decanal and (E)-2-decenal, the two compounds carrying most of the flavor, were not consistently affected. Storage costs you more aroma than a 3 kGy pathogen reduction dose does. For the fruit, dry toasting ruptures oil canals and releases aroma immediately, then volatilizes it.

Is dietary intake enough?

For the nutrients, yes and trivially, because coriander is not a meaningful source of anything at culinary doses. For the volatile oil, a teaspoon of ground fruit at 1.8 g carrying 0.5 percent oil gives about 9 mg of volatile oil, of which perhaps 6 mg is linalool. A 600 mg capsule of pressed seed oil contains no linalool at all, because the pressed oil is a fat. For the metal claim, intake is irrelevant, because the effect has never been demonstrated at any intake. Eat the spice because food tastes better with it. That is the whole food case.

Who Should Take Coriander

Almost nobody needs a coriander supplement, and the people most motivated to buy one are the people it will help least.

Who has a defensible reason to try it

• Adults with functional dyspepsia who have already been evaluated. Azimi and colleagues randomized 90 Rome IV dyspepsia patients in Kerman to a 500 mg capsule of Bunium persicum plus Coriandrum sativum or placebo, twice daily for 4 weeks. Forty per group completed, so the reported improvements in symptom severity, frequency and Nepean Dyspepsia Index are results in 80 patients, not 90, and they belong to a two-herb combination.

• Adults with irritable bowel syndrome whose main complaints are abdominal pain and bloating. Vejdani randomized 32 patients to Carmint, a fixed extract of Melissa officinalis, Mentha spicata and Coriandrum sativum, or placebo, each on top of loperamide or psyllium, for 8 weeks.

• People with interdigital tinea pedis who want a topical option. This is the single strongest coriander result, and it is a cream.

• Migraine patients already on preventive medication, as an add-on only. The trial design makes this explicit and the dosage section spells out why.

Who should get tested instead of supplemented

Anyone who came to coriander because they suspect metal exposure. The relevant action is measurement, not herbs. For children, the CDC blood lead reference value has been 3.5 micrograms per deciliter since 28 October 2021, down from 5 micrograms per deciliter set in 2012, derived as the 97.5th percentile of the blood lead distribution in US children aged 1 to 5 using NHANES 2015 to 2016 and 2017 to 2018. CDC states that no safe blood lead level in children has been identified and that the reference value is not a toxicity threshold. A blood lead test produces a number a clinician can act on. A bottle of cilantro extract does not.

Who should skip it entirely

Anyone with a diagnosed metal burden who might delay real treatment, anyone with an Apiaceae allergy, and anyone on warfarin who would start eating cilantro by the bunch.

Who Should AVOID or Use Caution

Contraindications

• Documented allergy to coriander or to another Apiaceae species. Immunoglobulin E mediated coriander allergy is real and published. Ebo and colleagues at the University of Antwerp described a spice factory worker with anaphylaxis after eating a meal containing coriander, plus urticaria, angioedema, rhinoconjunctivitis and bronchospasm while handling coriander and fenugreek. Specific IgE, skin tests and flow cytometric basophil activation measuring CD63 were all positive in the patient and negative in three healthy controls. Inhibition experiments showed no demonstrable cross-reactivity between fenugreek and coriander, so he was sensitized to both independently, and the history points to occupational exposure as the route.

• Confirmed lead, mercury, arsenic or cadmium toxicity requiring treatment. Coriander is not a substitute for a chelating agent and there is no evidence it is an adjunct to one.

Use Caution

• On warfarin or another vitamin K antagonist. Fresh cilantro at 310 micrograms of vitamin K1 per 100 g is not dangerous as a garnish, but a daily green smoothie with a full bunch is a swing in dietary vitamin K intake that will show up in an INR. The rule is consistency, not avoidance.

• On aspirin, clopidogrel, heparin or an NSAID. The platelet caution on coriander rests on in vitro platelet aggregation data, is rated a theoretical moderate interaction in the Natural Medicines database, and has no case report behind it. The standard handling for any herb with that flag: stop large medicinal amounts about two weeks before scheduled surgery.

• On a photosensitizing drug such as ciprofloxacin, a tetracycline or amitriptyline. Coriander fruit oil carries the furanocoumarin bergapten in traces, and the plant yields coriandrin, a furoisocoumarin Ashwood-Smith found in 1989 to be more photoactive than psoralen in cells but only weakly photosensitizing on skin. The interaction is mechanistic rather than documented in a human case series, which is why it sits under caution rather than contraindications.

• Pregnancy and lactation at medicinal doses. Culinary use is food. Beyond that the safety data do not exist, which is a statement about the evidence rather than a reassurance.

• Diabetes on glucose-lowering medication. Rodent work shows coriander extracts and oil lowering serum glucose and improving glucose tolerance. None of it has been replicated in a human glycemic trial, so the practical concern is unquantified rather than absent.

Critical Safety Point

The worst outcome in this entire file is a parent reading a chelation claim, giving a child a cilantro glycerite, and not getting a blood lead test. Lead is a developmental neurotoxicant with no identified safe blood level, elevated results in children are managed with environmental removal and, above specified thresholds, with prescription chelators under supervision, and every week of delay is irreversible. The Source Naturals label carries the standard disclaimer that its statements are not FDA evaluated and that the product is not intended to treat any disease. Read that sentence as the operative instruction, not as fine print.

Recommended Dosages

There is no recommended dose of coriander for metal removal because there is no demonstrated effect to dose for. Every number below belongs to a specific preparation in a specific study or a specific regulatory ceiling, and none of them is an instruction.

Culinary spice

No limit of concern. A teaspoon of ground fruit is about 1.8 g, a tablespoon about 5 g.

Pressed coriander seed oil, regulatory ceiling

600 mg per day in food supplements in the European Union, set by Decision 2014/155/EU. This is a maximum the Commission permitted, derived from the applicant's intended use and a safety assessment. It is not a dose anybody established as effective for anything.

Doses used in published human trials

• Bunium persicum plus Coriandrum sativum, 500 mg capsule twice daily for 4 weeks, in 90 randomized dyspepsia patients with 80 analyzed (Azimi 2024). Coriander was one of two herbs in the capsule and its individual contribution is unknown.

• Coriander seed powder 2 g per day for 40 days in a four-arm study of 80 hyperlipidemic patients, 20 per arm, against garlic powder and a 1:1 mixture (Zeb 2018).

• Coriander fruit syrup 15 mL three times daily for one month, given in addition to 500 mg per day of sodium valproate, in 68 randomized migraine patients with 66 analyzed (Delavar Kasmaei 2016). Both arms received valproate. The trial measured coriander plus an anticonvulsant against the anticonvulsant alone.

• Carmint, a fixed three-herb extract, for 8 weeks in 32 IBS patients, each arm also receiving loperamide or psyllium (Vejdani 2006).

Topical doses

• 6 percent coriander fruit oil in unguentum leniens, applied twice daily to affected interdigital spaces, assessed at days 14 and 28 (Beikert 2013).

• 0.5 percent and 1.0 percent fruit oil in a lipolotion, occlusive, for a single 47 hour exposure in the ultraviolet erythema model (Reuter 2008).

Coriander essential oil taken internally

No established dose and no trial. PubMed indexes no human oral tolerance study of coriander essential oil.

Duration

The human exposures above ran 48 hours to 8 weeks. The longest was the Vejdani IBS trial at 8 weeks. None of the controlled trials in this file went beyond 8 weeks.

Timing & Administration

With food for anything digestive. The traditional indication is postprandial: bloating, fullness, flatulence after eating. The Azimi capsule was taken twice daily. PubMed indexes no human pharmacokinetic study of any coriander preparation to arbitrate timing.

Whole fruit cracked, not dusted. Crush the fruit immediately before use. The oil lives in canals inside the ridges, and pre-ground coriander left open has already surrendered most of it.

Tea preparation. Infuse crushed fruit in near-boiling water, covered, because an uncovered infusion vents the volatile fraction with the steam. No pharmacopeia specifies a coriander infusion strength, since no European monograph exists, so any number on a label is the manufacturer's.

Topical. Apply the 6 percent ointment after washing and drying the interdigital spaces, and keep the bergapten point in mind on exposed skin.

Fresh leaf at the end of cooking. The green note compounds, (Z)-3-hexenyl acetate at 66 to 77 percent of fresh leaf headspace in the Kumar cultivars, do not survive distillation and will not survive a simmer. Add at the end or raw.

Timeline of Effects

Immediately to within a meal, for the carminative use. That is the traditional claim. No published study reports a measured time to effect for coriander on bloating, gas or postprandial fullness.

14 days, for the topical antifungal. Beikert's half-side comparison of 6 percent fruit oil in 40 participants, mean age 52.5 years and 60 percent male, improved clinical signs at p less than 0.0001 with assessments at days 14 and 28. Positive fungal cultures only tended to decrease, p = 0.0654. Signs improved faster and more convincingly than the fungus cleared.

48 hours, for the anti-inflammatory topical. Reuter's ultraviolet erythema model irradiated at 1.5 times the minimal erythema dose and measured photometrically at 48 hours. The 0.5 percent lipolotion significantly reduced erythema against placebo and was less effective than 1.0 percent hydrocortisone. The report states significance for the 0.5 percent arm and reports none for the 1.0 percent arm. A later 40-subject study by an overlapping Hamburg group tested seven plant extracts including Coriandrum sativum in the same model and found that only Aloe vera reached statistical significance; coriander showed an effect against both controls that did not.

4 weeks, for migraine. Delavar Kasmaei followed patients weekly for four weeks. Mansouri reanalyzed the same 68 patients with a mixture model in 2020 and reported that the probability of being migraine free was higher in the final weeks than earlier, and higher in patients under 30 than over 30. So the fair trial length here is four weeks, on top of existing prophylaxis, and the effect appeared late rather than early.

4 to 8 weeks, for dyspepsia and IBS. Azimi treated for 4 weeks and followed for 4 more. Vejdani ran 8 weeks.

When to conclude it is not working. If you are taking coriander for a digestive complaint and have had no change after 4 weeks at a consistent dose, the trials give you no reason to expect week 8 to be different. If you are taking it to remove metals, there is no timeline, because there is no measured endpoint to be on a timeline toward.

Benefits of Taking Coriander

Interdigital tinea pedis, topical. The best coriander result in the literature, and still a 40-subject pilot that was not powered for mycological cure.

Topical antibacterial activity. Fruit oil inhibited Streptococcus pyogenes at a mean 0.04 percent v/v and MRSA at 0.25 percent v/v in standardized macrodilution against clinical isolates. That is in vitro potency plus human skin tolerance, not a treatment trial in infected patients.

Functional dyspepsia, as part of a combination. Significant improvement across the Dyspepsia Severity Questionnaire, Rome IV questionnaire and Nepean Dyspepsia Index in 80 analyzed patients, with no serious side effects reported. The coriander-specific contribution is unmeasured.

Abdominal pain and bloating in IBS, as part of a combination. Carmint reduced severity and frequency of pain (p = 0.016 and p = 0.001) and of bloating (p = 0.02 and p = 0.002) over 8 weeks in 32 patients, every one of whom was also on loperamide or psyllium.

Migraine, as an add-on. Coriander fruit syrup plus 500 mg sodium valproate beat valproate plus placebo in 66 analyzed patients, with mean attack duration 5.7 hours shorter, severity 3.65 units lower and frequency roughly 50 percent lower. Single center, single trial.

Lipids and blood pressure. Coriander seed powder at 2 g per day moved total cholesterol, LDL, triglycerides, HDL, BMI and systolic pressure significantly over 40 days, with the authors noting garlic outperformed coriander on cholesterol and LDL while coriander's effect was largest on blood pressure. Twenty patients per arm, single blind.

Where there is no benefit to report. Metal removal and the salivary microbiome. The measured nulls are part of the benefit picture.

Potential Negatives & Side Effects

Allergy, the one real risk. Coriander sensitization is IgE mediated and can present as anaphylaxis on ingestion in someone sensitized by handling the spice occupationally. The Antwerp case had urticaria, angioedema, rhinoconjunctivitis and bronchospasm on handling and systemic reaction on eating. Contact urticaria and itching on skin exposure are also reported. A reaction to coriander does not predict a reaction to fenugreek or the reverse, because the Antwerp inhibition work found no demonstrable cross-reactivity between them.

Photosensitivity. The furanocoumarin content of coriander fruit is trace rather than substantial, so the risk is lower than for the Apiaceae species known for phytophotodermatitis, but bergapten and coriandrin are there and a known interaction category exists with photosensitizing drugs. If you are on a tetracycline and applying coriander oil to exposed skin, cover the area.

Skin tolerance at low concentrations is good. Two 40-subject occlusive patch assessments at 0.5 and 1.0 percent fruit oil found no photometrically detectable irritation. That says nothing about undiluted oil.

Bleeding risk. Flagged as a moderate interaction category for anticoagulant and antiplatelet drugs and as a reason to stop large amounts before surgery. No published bleeding case report is attributed to coriander, so this is flagged rather than demonstrated.

Gastrointestinal upset. Not reported as a signal in the combination trials, which recorded no serious adverse effects. The Azimi trial excluded patients with a history of herbal drug allergy at enrollment, which removes the group most likely to react and makes that safety record less generalizable than it reads.

Contamination, which is not a property of the plant. The largest documented harm associated with coriander in a controlled study came from what was in it rather than what it is, and the quality section gives the figure.

Deficiency Symptoms

What coriander deficiency addresses: nothing, because there is no coriander deficiency state. No human requirement has been established for linalool, petroselinic acid, (E)-2-decenal or any other coriander constituent, and no deprivation syndrome has been described.

The contrast worth drawing is with a genuine trace element. Iodine deficiency has a measurable biomarker (urinary iodine concentration), a defined population threshold, a named clinical syndrome and a public health intervention with a century of data. Coriander has none of those four things, because it is a spice rather than a nutrient.

Bottom line: if a label implies you are running low on coriander, the label is describing a market gap rather than a physiological one.

Toxicity Symptoms

At high intake: no human toxic syndrome has been characterized for coriander fruit or leaf at any intake, culinary or supplemental. That is an absence of reports rather than a demonstration of safety at high doses, and the distinction matters because the oral doses studied in humans top out at 2 g of seed powder or 45 mL of fruit syrup per day.

Signs to reduce or stop: urticaria, lip or facial swelling, throat tightness, wheeze or rhinoconjunctivitis after ingestion or handling. Those are allergy, they can escalate, and they are the only acute presentation with a published human precedent. A rash on skin that only touched the oil is more likely irritant or contact urticaria. A reaction with breathing involvement is an emergency, not a dose adjustment.

General note: the hazard profile of this plant is dominated by three things that are not the plant: allergy in a sensitized person, contamination of the raw material, and the opportunity cost of using it instead of a diagnosis. The concentrated essential oil deserves separate caution because nobody has published a human oral study of it, and an oil that is two thirds one monoterpene alcohol is not a culinary quantity by the spoonful.

How Coriander Works

Carminative action, the mechanism behind the only approved indication. A carminative relaxes smooth muscle in the gut wall and the lower esophageal region, which lets trapped gas move rather than distend. Monoterpene alcohols do this, and linalool is a monoterpene alcohol at 60 to 80 percent of the fruit oil. The sequence credited to coriander is local smooth muscle relaxation plus reduced spasm, which is why the approved wording is dyspeptic complaints and loss of appetite rather than anything about transit time or emptying. PubMed indexes no human manometry or gastric emptying study of coriander, so the mechanism is inferred from the chemical class and from traditional use, not measured in people.

Linalool in the central nervous system. Proposed to act as a competitive antagonist at ionotropic NMDA receptors, inhibiting glutamate release, with antidepressant-type effects in rodents mediated through the GABA receptor complex. Emamghoreishi and Heidari-Hamedani injected aqueous and hydroalcoholic seed extracts into mice before pentylenetetrazole in 2008 and reported median effective doses against death of 327 and 560 mg/kg. Those are injected animal doses by body weight and they do not convert to a human capsule.

Petroselinic acid and fatty acid desaturation. The pressed seed oil's distinguishing feature is a monounsaturated acid with its double bond at carbon 6 rather than carbon 9. Structurally it resembles a precursor in the arachidonic acid pathway, and it is proposed to suppress arachidonic acid formation by inhibiting delta-6-desaturase. The European novel food authorization rests on EFSA's October 2013 safety opinion, not on that mechanism, and the mechanism has not been demonstrated as a clinical endpoint in humans.

Antimicrobial membrane disruption. Linalool permeabilizes bacterial membranes and depolarizes them, collapsing metabolic function. This is the mechanism with the most direct support, because the in vitro MICs and the topical trials line up with it.

The metal binding question, which is where the mechanism runs out. Chelation in any rigorous sense means a defined ligand forming a coordination complex with a metal ion at a measurable stability constant. Coriander has no such identified ligand. Aga and colleagues wrote that their mouse result "probably" resulted from chelation of lead by "some substances contained in Chinese parsley," and twenty-five years later those substances are still unnamed. Sharma, Kansal and Sharma closed their 2010 testis paper by stating that further work is needed to isolate and purify the active principle behind the antioxidant protection they measured. Téllez-López and colleagues opened their 2017 rat paper by stating that coriander is said in traditional medicine to have chelating properties but there is no scientific evidence to support it. Three research groups sympathetic to the hypothesis, across sixteen years, all said the compound had not been found. That is the actual state of the mechanism.

Synergistic Supplements

Coriander's problem is the opposite of synergy. Almost every positive human result it has was produced inside a mixture, which means the mixture is the evidence and coriander is a component.

Combinations with actual human data

• Bunium persicum (black caraway) plus coriander, 500 mg twice daily, the dyspepsia trial. Two herbs, one capsule, one result.

• Melissa officinalis plus Mentha spicata plus coriander, marketed as Carmint, the IBS trial. Three herbs, plus loperamide or psyllium in every patient.

• Coriander inside Smooth Move, a senna-based laxative tea that also carries licorice, fennel, ginger, cinnamon bark and orange peel. Bub's 28-day trial in 86 nursing home residents produced 4.14 more bowel movements than placebo (p = 0.017). The laxative there is senna and that mechanism belongs to another issue in this archive.

• Chlorella plus cilantro leaf, the commercial metal pairing. No human trial of that combination on any metal endpoint exists.

The honest reading

A product page citing Azimi, Vejdani or Bub is citing a trial of something else that contained coriander. For single-ingredient oral coriander the whole file is the migraine add-on trial and the 20-patient lipid arm.

Interactions & What NOT to Take

Warfarin and other vitamin K antagonists. The interaction is dietary vitamin K1, 310 micrograms per 100 g of fresh leaf. A garnish is irrelevant. A daily smoothie with a whole bunch is not. Keep intake steady rather than zero, and tell whoever manages your INR if it changes.

Aspirin, clopidogrel, warfarin, heparin, ibuprofen. Listed as a moderate caution for additive bruising and bleeding risk with large amounts of coriander. No human case report supports it. Stop large medicinal amounts about two weeks before surgery.

Ciprofloxacin, tetracyclines, amitriptyline and other photosensitizers. Additive photosensitivity, on the strength of coriander's trace bergapten and coriandrin. Sun protection on treated or exposed skin.

Sodium valproate. Not a hazard but a design fact that determines how to read the migraine result. Every patient in both arms received 500 mg per day. The trial establishes that coriander syrup added something to valproate. It establishes nothing about coriander alone, and it is not a reason to reduce an anticonvulsant.

Glucose-lowering drugs. Animal data show coriander oil and extracts reducing serum glucose. No human glycemic trial exists, so the theoretical additive effect cannot be quantified. Anyone on insulin or a sulfonylurea starting a 2 g daily seed powder should be checking glucose rather than assuming nothing.

Chelating agents. Do not substitute coriander for succimer, dimercaprol, edetate calcium disodium or any other prescribed chelator, and do not add it on the theory that it helps. Aga's mouse model used meso-2,3-dimercaptosuccinic acid as its positive control because DMSA works and the model needed validating against something that does.

Quality, Testing & Adulteration

The documented contamination case, with a number. Sathyanarayana and colleagues ran a randomized dietary intervention in 10 families intended to reduce phthalate and bisphenol A exposure. In the complete dietary replacement arm, 21 participants, urinary di(2-ethylhexyl) phthalate metabolites rose from a median 283.7 nmol/g at baseline to 7,027.5 nmol/g during the intervention, p less than 0.0001, while the written-advice arm of 19 showed no significant change. Ingredient testing traced it: ground coriander in the study food contained DEHP at 21,400 ng/g, against 673 ng/g in the milk. Estimated DEHP daily intake for children in that arm exceeded both the EPA oral reference dose and the EFSA tolerable daily intake. A trial designed to lower a contaminant raised it twenty-five-fold through a spice.

The irony in the metal claim. The plant marketed to remove lead accumulates it. Atamaleki and colleagues meta-analyzed 32 articles covering 41 studies of wastewater-irrigated produce and reported pooled concentrations in the edible part of coriander of iron 1,056 mg/kg, zinc 79.80, chromium 28.34, nickel 24.71, copper 17.46, lead 13.23 and cadmium 2.23 mg/kg. Across the review's two crops the total target hazard quotient for adults exceeded 1 in every country analyzed except the UAE, France and Kenya. Ugulu and colleagues sampled coriander beside a sugar mill in Sargodha and found cadmium at 1.245 mg/kg with a health risk index of 173.2. A 2026 multi-matrix survey in Pakxong District, Laos, found coriander carrying lead at 0.066 to 0.074 mg/kg fresh weight while green cabbage from the same three sites was non-detect and Chinese cabbage ran from non-detect to 0.022 mg/kg.

The microbiological record. FDA Import Alert 24-23 places fresh cilantro from the state of Puebla, Mexico, under detention without physical examination every year from 1 April to 31 August. The basis is recurring US cyclosporiasis outbreaks in 2012, 2013, 2014 and 2015, FDA detections of Cyclospora cayetanensis in cilantro from multiple Puebla firms, and joint 2013 to 2015 inspections with SENASICA and COFEPRIS that found human feces and toilet paper in growing fields, missing toilets and handwashing facilities, and at one firm C. cayetanensis in a handwashing holding tank. FDA concluded the outbreaks were not isolated events. The alert covers intact and cut fresh cilantro and explicitly does not cover dried cilantro or multi-ingredient processed foods, so it tells you nothing about the dried leaf in a capsule.

What third-party testing covers and does not. USP's Dietary Supplement Verification and NSF/ANSI 173 certification both check identity, declared potency, contaminant limits and manufacturing practice. None of them evaluates whether the claim on the front of the bottle is true. A verified mark on a cilantro metal detox product would confirm that the bottle contains the declared weight of cilantro leaf and passes heavy metal limits. It would not confirm that cilantro leaf removes metals, because that is not what the program is for.

What a buyer can pin down without a laboratory

Read the Supplement Facts panel for the Latin binomial and the plant part, because "coriander" and "cilantro" on a front label are marketing words and fruit and leaf are different drugs. Look for an extract ratio and a solvent; a glycerite with neither is unquantified by construction. Look for a declared marker, which for fruit oil means a linalool percentage and for pressed seed oil a petroselinic acid percentage against the 60 to 75 percent window. Ask for a certificate of analysis and check that its heavy metal panel covers lead, cadmium, arsenic and mercury rather than two of the four, and that the figures are measurements rather than "less than" limits of quantification, which describe the instrument. Then check whether any citation on the product page used the plant part in the bottle.

Special Considerations

Some people genuinely taste soap. Eriksson and colleagues ran a genome-wide association study in 14,604 participants of European ancestry, of whom 1,994 (13.7 percent) reported that cilantro tastes soapy, and identified rs72921001 on chromosome 11 at p = 6.4 x 10 to the minus 9, with an odds ratio of 0.81 per A allele (95 percent CI 0.753 to 0.870). Replication in a second set of 11,851 people answering a preference question gave p = 0.0057 and an odds ratio of 0.92 for disliking cilantro. The nearest candidate gene is the olfactory receptor OR6A2, sitting in a cluster of olfactory receptor genes. The effect is real and small: a single common variant explains a sliver of the variance, so the genotype does not determine the preference.

The two-plants-one-name problem is a sourcing problem. Retailers and secondary databases move between "coriander" and "cilantro" without noting the plant part, and the research follows the word rather than the material. A composition table that does not state seed or leaf is unusable, and published ones often do not.

Another plant is also sold as coriander. Eryngium foetidum, wild coriander or culantro, is a different Apiaceae genus whose leaf oil was dominated by (E)-2-dodecenal at 63.5 percent of total ion chromatogram area in the Otago work, against a decenal-dominated profile in C. sativum. They substitute for each other in Caribbean and Southeast Asian cooking and not as research material.

Children. Culinary coriander is food. A supplement given to a child for metal removal is the scenario the safety section exists for.

Research Status & Evidence Quality

Tier 1, randomized human evidence with a consistent direction: topical coriander fruit oil. One 40-subject half-side antifungal pilot and one 40-subject anti-inflammatory model, both from the same German groups, plus a 40-volunteer skin tolerance assessment. Small, single-origin, and the strongest thing coriander has.

Tier 2, randomized human evidence inside a combination: dyspepsia (80 analyzed of 90 randomized, two herbs), IBS (32 patients, three herbs plus a drug), constipation (86 residents, seven ingredients including senna). Positive and uninterpretable at the ingredient level.

Tier 3, single randomized trial, add-on or single-arm design: migraine (66 analyzed of 68, coriander syrup on top of valproate), lipids and blood pressure (20 patients per arm, single blind).

Tier 4, in vitro and animal only: antidiabetic, hypolipidemic, anticonvulsant, anxiolytic, hepatoprotective, anti-aging, anthelmintic, insecticidal, allelopathic. Large literature, no human replication.

Tier 5, measured nulls: salivary microbiome at 14 days against water, coriander failing to reach significance in the seven-extract erythema comparison, and mycological cure in the tinea pedis pilot.

Tier 6, no human evidence at all: metal binding or removal in people. The record is rodent work (Aga 2001 in ICR mice, Sharma 2010 in mice, Velaga 2014 in Wistar rats on seed extract at 250 and 500 mg/kg, Téllez-López 2017 in Wistar rats on methanol extract at 50 mg/kg, and others since) plus a 1995 case series of 11 patients assessed by a patented finger-strength test.

Research Limitations

Most of the human trial literature comes from a few centers in Iran and Pakistan with small samples, single blinding in places, and no registered protocols. The animal work rarely reports the plant part in terms a buyer could match to a product: Aga dosed Chinese parsley, Velaga a seed extract, while the metal-claim products are leaf glycerites. The chemistry literature is extensive and reliable, and it is the part of this file you can lean on. No dose-ranging study exists for any human indication, PubMed indexes no human pharmacokinetic study of any coriander preparation, and none of the controlled trials ran beyond 8 weeks.

Summary & Key Takeaways

Bottom Line

Coriander is two materials with one name. The dried fruit is 0.18 to 1.40 percent volatile oil, 60 to 80 percent of it linalool, with a Commission E approval for dyspeptic complaints and loss of appetite and no EU herbal monograph at all. The fresh leaf is a vitamin K1 source whose oil is more than 70 percent aliphatic aldehydes and 0.1 to 0.5 percent linalool. The best-supported use of either is a 6 percent fruit oil ointment for athlete's foot, from one 40-person pilot. The heavy metal chelation claim printed on cilantro products rests on a 1995 case series of 11 patients assessed by a patented finger-strength maneuver, rodent studies in which three separate groups said the active compound had not been isolated, and no controlled human trial of any metal endpoint.

Key Safety Points

• Suspected metal exposure calls for a blood test, not a supplement. The CDC blood lead reference value for children has been 3.5 micrograms per deciliter since 28 October 2021, and CDC states no safe blood lead level has been identified. Delay in a child is irreversible.

• Never substitute coriander for a prescribed chelator. The mouse study everyone cites used DMSA as its positive control because DMSA works.

• Coriander anaphylaxis is documented and IgE mediated, with occupational handling as a sensitization route. Urticaria, facial or throat swelling or wheeze after coriander is an emergency, not a dose question.

• Fresh cilantro carries 310 micrograms of vitamin K1 per 100 g. On warfarin, keep intake steady and tell whoever runs your INR.

• Coriander fruit contains trace bergapten. With a photosensitizing drug, cover treated or exposed skin.

• Coriander essential oil has no published human oral tolerance study. Do not swallow it.

• Leafy coriander accumulates metals. Pooled lead was 13.23 mg/kg and cadmium 2.23 mg/kg in the edible part under wastewater irrigation. Sourcing matters more than any claim on the bottle.

Special Note

The strangest fact in this file is that a randomized trial designed to reduce chemical exposure increased it through coriander. Sathyanarayana's complete dietary replacement arm saw urinary DEHP metabolites rise from a median 283.7 to 7,027.5 nmol/g, and the ground coriander in the study food tested at 21,400 ng/g of DEHP. A spice sold as a way to clear contaminants from the body delivered a contaminant into 21 people, in a study whose entire purpose was the opposite. Nobody set out to prove that. It is the closest thing in this literature to a randomized human measurement of what coriander does to a measured chemical burden, and it points the wrong way.

Researched and drafted with AI assistance. Every claim verified against primary sources and human-reviewed before publication. Last reviewed: October 15, 2026. Corrections: reply to any issue.

This issue is educational and is not medical advice. If you take prescription medication or have a diagnosed condition, talk to a clinician before adding or stopping anything, including a spice in supplement form.