IngredientsScientific name: Citrus junos Sieb. ex Tanaka (also written Citrus × junos to reflect its hybrid origin). It belongs to the family Rutaceae and the genus Citrus. In Korea the fruit is called yuja; in China it is sometimes called xiāng chéng.
Citrus junos originated in China as a natural cross between C. reticulata Blanco and C. cavaleriei H. Lév. ex Cavalerie; it has a thick and lumpy peel, is yellow when ripe with little pulp, and has numerous large seeds inside. Its taste is slightly sour, intermediate between grapefruit and mandarin, and the fruit — oblate to nearly pyriform and 4–8 cm in diameter — is widely used in Japanese cuisine but rarely consumed as a fresh fruit.
The fruit is small, with a diameter of approximately 2–3 inches (5.5–7.5 cm), and has a relatively thick yellow skin; it is more aromatic and much sourer than other citrus fruits.
Particularly popular in East Asian cuisine, its juice, peel, and seeds serve as gourmet flavorings for vinegars, seasonings, sauces, and marmalades. Yuzu oil is also commonly used in cosmetics, perfume, and aromatherapy.
Documented forms include:
Historical records suggest yuzu originated in the upper reaches of the Yangtze River in China, where winter temperatures regularly drop below freezing. This harsh mountain environment created a citrus unlike any other; while regular citrus trees would die in such conditions, yuzu thrived. From China, yuzu traveled to Korea, where it became deeply embedded in traditional medicine and cuisine.
It reached Japan through the Korean Peninsula sometime before the Nara period, flourishing around 1,300 years ago, and was grown in western Japan to be used as medicine. Historical records suggest it was first cultivated in Japan during the Nara period (710–794 AD), after which it became an integral part of Japanese culture and cuisine.
Currently, yuzu is grown in Korea, Australia, Spain, Italy, France, and China — where it originated.
In Japan, it is believed that yuzu was introduced in the 8th century from China and became widely cultivated during the Edo period. Its earliest documented Japanese use was medicinal; the culinary role developed subsequently. In Japan it was quickly embraced not only as a seasoning but also as a remedy. One of the most famous traditions is the yuzu-yu: a yuzu-infused bath taken on the winter solstice to prevent colds and strengthen the immune system, with whole yuzu fruits placed in hot water, slowly releasing their essential oils.
In Korea, yuzu has been grown since the 17th century and has become an integral part of Korean cuisine. Korean families prepare yuzu-cha (citron tea) as soon as the first yuzu fruits ripen. This thick, honey-like preserve made from yuzu rind and pulp becomes the family's winter medicine, stirred into hot water whenever someone feels a cold coming on. In Korea, yuja tea is a popular traditional remedy for cold symptoms, sore throat, and fatigue.
Chinese traditional medicine values yuzu for its "warming" properties. Unlike cooling citrus like oranges and grapefruits, yuzu is considered a yang food that helps balance the body during cold months.
The main flavonoids in yuzu are naringin, narirutin, hesperidin, neohesperidin, naringenin, and hesperetin. Additional flavonoids documented include: hesperidin, naringin, rutin, rutin hydrate, narirutin, apigen-7-glucoside, quercetin, and tangeretin. A wider panel including eriocitrin, neoeriocitrin, narirutin, naringin, hesperidin, neohesperidin, diosmin, didymin, poncirin, nobiletin, and tangeretin has been identified by HPLC across the whole fruit and juice.
The means of vitamin C, naringin, and hesperidin in yuzu were 90.4, 63.8, and 65.7 mg/100 g fresh yuzu, respectively. The amounts of phenolics, vitamin C, and antioxidant activity in all tested yuzu cultivars were higher in peel than in flesh.
Yuzu contains large amounts of vitamin C and flavonoids, such as hesperidin and limonin. These flavonoids have been reported to have high anti-inflammatory and antioxidant activity. More specifically, flavonoids extracted from citrus species — in particular hesperidin and naringin — have been reported to reduce the expression of inflammatory cytokines such as tumor necrosis factor-α, interleukin-1, and interleukin-6.
The major components of yuzu essential oil are: limonene 78.02%, γ-terpinene 9.32%, β-myrcene 1.77%, α-pinene 1.34%, δ-elemene 0.79%, β-pinene 0.69%, β-caryophyllene 0.60%, α-phellandrene 0.43%, and terpinolene 0.41%.
The essential oils of six different yuzu cultivars were extracted by the cold-pressing method; a total of 69 compounds were identified. GC-olfactometry indicated eight odorants with the highest flavor dilution (FD) values: limonene, α-pinene, α- and β-phellandrene, myrcene, γ-terpinene, (E)-β-farnesene, and linalool.
A compound of special interest is yuzunone: aroma extract dilution analysis identified seven odorants including (6Z,8E)-undeca-6,8,10-trien-3-one (Yuzunone) and (6Z,8E)-undeca-6,8,10-trien-4-ol (Yuzuol) as odor-active volatiles with the highest flavor dilution factors; among the most odor-active volatiles, (E)-non-6-enal and Yuzunone were identified for the first time solely in yuzu peel oil and not in the peel of other citrus.
The second major component of yuzu, γ-terpinene (9.32%), promotes dopamine release, resulting in stress reduction. Yuzu also shares components with lavender — a representative relaxing essential oil — such as β-caryophyllene and linalool, which also have sedative effects.
A new limonoid derivative, junosterpene, was isolated from the seeds of C. × junos, along with seven known limonoids: 21,23-dihydro-23-hydroxy-21-oxodeacetylnomilin, deacetylnomilin, 21,23-dihydro-21-hydroxy-23-oxonomilin, obacunoic acid, methyldeacetylnomilinate, limonin, and ichangin, as well as three known furanocoumarins.
Yuzu seeds contain a limonoid mixture consisting of deacetylnomilin (105 mg g⁻¹ of dry seeds), limonin (95 mg g⁻¹ of dry seeds), nomilin (115 mg g⁻¹ of dry seeds), and obacunone (17 mg g⁻¹ of dry seeds).
Limonoids isolated from C. junos seeds include methyl sudachinoid A, sudachinoid B, ichangensin, 1-O-methylichangensin, nomilin, deacetylnomilin, methylnomilinate, methyldeacetylnomilinate, deacetylnomilinic acid-17-O-glucopyranoside, nomilinate A ring lactone, obacunone, limonin, and ichangin.
Several active compounds such as rutin, quercetin, tangeretin, naringin, and hesperidin are found in the fruit; these antioxidants prevent or retard the oxidation of other molecules by interrupting the initiation or propagation of oxidizing chain reactions. Such metabolites also exhibit significant protective biological activities, including anticancer, anti-inflammatory, and antiviral properties.
Yuzu peel and seed contain abundant vitamin C, citric acid, and polyphenols. Yuzu also contains various phenolic compounds such as chlorogenic acid, ferulic acid, rutin, rutin hydrate, narirutin, naringin, apigen-7-glucoside, hesperidin, quercetin, and tangeretin.
This is the area in which yuzu has the most — and the most rigorous — human clinical evidence to date.
Study 1 (RCT, n=20, 2014 — PubMed PMID 24742226): Ten-minute inhalation of the yuzu scent significantly decreased salivary chromogranin A (CgA), a stress marker; at 30 minutes after the inhalation period, the salivary CgA level further decreased. Profile of Mood States (POMS) tests revealed that inhalation of the aromatic yuzu oil significantly decreased total mood disturbance, together with four subscores of emotional symptoms — tension-anxiety, depression-dejection, anger-hostility, and confusion — as long as 30 minutes after the olfactory stimulation. The authors concluded that yuzu's aromatic effects may alleviate negative emotional stress, which, at least in part, would contribute to the suppression of sympathetic nervous system activity.
Study 2 (single-blind randomized crossover RCT, PubMed PMID 27103942): Only a 10-minute inhalation of the yuzu scent significantly decreased heart rate and increased high-frequency power of HRV reflecting parasympathetic nervous system activity, regardless of menstrual phase. This significant physiological effect continued for at least 25 minutes. POMS tests further revealed that inhalation of the aromatic yuzu oil significantly decreased total mood disturbance together with two POMS subscales — tension-anxiety and fatigue — for as long as 35 minutes after the aroma stimulation, both in the symptomatic late-luteal and non-symptomatic follicular phases.
Study 3 (clinical study, n=121 — cited in review PMC4839105): A clinical study with 121 participants (aromatherapy group n=61, control group n=60) showed that aromatherapy with yuzu fragrance significantly ameliorated the anxiety of mothers of sick children undergoing an infusion at a pediatric clinic. This study did not measure any physiological data including HRV measurements.
Evidence strength: Studies from Japanese scientific journals suggest the healing effects of yuzu fragrance and its potential application to aromatherapy; however, an extensive literature search revealed a paucity of empirical human-subject research regarding the efficacy of yuzu fragrance on the psychophysiological health for women. The existing human data consistently shows short-term anxiolytic and autonomic effects, but studies have small sample sizes, are single-blind at most, and have short follow-up. Independent replication and blinded designs are lacking.
Citrus fruits contain dietary components such as hesperidin, naringin, limonene, and vitamin C, which confer health benefits that include preventing cardiovascular disease and improving blood circulation.
In vitro and animal evidence (PMC4354316): Oral administration of yuzu methanol extract or hesperidin prolonged mouse tail vein bleeding time in a dose-dependent manner in vivo. These results suggest that yuzu methanol extract and hesperidin have anti-platelet activity, and that intake of yuzu — which includes various flavonoids such as hesperidin — may be beneficial for individuals at high risk of cardiovascular diseases.
The methanol extract of yuzu could be beneficial for individuals at high risk of cardiovascular disease because it inhibits platelet aggregation. Yuzu extract could be useful in treating heart failure as it prevents myocardial infarction-induced ventricular dysfunction and structural remodeling of myocardium.
Evidence strength: Evidence is currently preclinical (in vitro and animal models). No published human clinical trials on yuzu-specific cardiovascular or antiplatelet endpoints were identified in the literature. The findings are mechanistically plausible given the flavonoid content but cannot be extrapolated to humans without controlled trials.
In vitro and mouse model evidence (PMC3674686): The antidiabetic effect of Citrus junos Tanaka was examined. Ethanol extract of yuja peel (YPEE) significantly stimulated glucose uptake in C2C12 myotubes. However, ethanol extract of yuja pulp and water extract of yuja peel or pulp did not stimulate glucose uptake. In addition, PPAR-γ and AMP-activated protein kinase (AMPK) activities were increased by YPEE in a dose-dependent manner. The authors confirmed the anti-diabetic effect of YPEE in mice fed a high-fat diet.
Yuzu peel extract showed anti-obesity effects in a zebrafish model via activating hepatic PPAR-α and adipocyte PPAR-γ pathways.
Yuzu's numerous health functions as identified in cell and animal research include anti-inflammatory, antioxidant, antidiabetic, anticarcinogenic, neuroprotective, and antihypertensive activities.
Evidence strength: Preclinical only. No controlled human trials on glycemic outcomes were identified. Results from cell culture and rodent models provide a mechanistic basis but do not constitute clinical evidence.
Yuzu essential oil is useful in treating bronchial asthma due to its anti-inflammatory activities. It inhibits the production of cytokines and reactive oxygen species, and reduces eosinophil migration.
To identify natural products having efficacy against inflammatory bowel disease (IBD), researchers isolated 13 limonoids including a new compound, methyl sudachinoid A, from yuzu seeds. The effect of these limonoids on LPS-induced pro-inflammatory cytokine production was studied in RAW 264.7 cells; the cells were pretreated with the compounds at 1, 10, and 100 µM for 2 hours and then stimulated with 1 µg/mL LPS for 18 hours; the amounts of IL-1β, IL-6, and TNF-α in the culture medium were measured.
A murine colitis model study (PubMed PMID 29459515) examined yuzu peel extract in dextran sulfate sodium-induced murine experimental colitis, a well-known model for inflammatory bowel disease; the authors noted a desire for prevention and attenuation of ulcerative colitis by food rich in functional ingredients without side effects.
Evidence strength: Anti-inflammatory effects have been documented in cell culture and animal models. No human clinical trials on inflammatory endpoints specific to yuzu have been identified.
A study investigated the variations in vitamin C, total phenolic, hesperidin, and naringin contents, and total antioxidant activity of yuzu between cultivars and during maturity. The amounts of phenolics, vitamin C, and the antioxidant activity in all tested cultivars were higher in peel than in flesh. Ripening increased the total antioxidant activity and vitamin C content in both peel and flesh of yuzu.
The relative vitamin C equivalent antioxidant capacity (VCEAC) values were in the following order: vitamin C (1.00) > naringin (0.195) > hesperidin (0.162). The estimated contribution of each antioxidant to the total antioxidant capacity of 100 g of fresh yuzu was: vitamin C (90.36 mg VCEAC) > naringin (12.44 mg) > hesperidin (10.64 mg).
The great potential of citrus-based extracts lies in their health-promoting ability, exhibiting a wide spectrum of bioactivities, such as antioxidant, anti-inflammatory, and antiproliferative activity against cancer.
Evidence strength: Antioxidant activity is well characterized in analytical and in vitro studies. Whether oral consumption of yuzu translates to meaningful in vivo antioxidant effects in humans has not been established by controlled trials.
Yuzu essential oil inhibited the formation of the carcinogen N-nitrosodimethylamine (NDMA) in vegetables (by 22–59%) and saliva (by 24–62%).
Citrus limonoids obacunone and limonin are considered possible chemopreventive agents against colon carcinogenesis, based on preclinical evidence.
Limonoids — a family of triterpenoids with putative anticancer properties — from citrus fruits were tested for toxic effects against human cancer cell lines, SH-SY5Y neuroblastoma and Caco-2 colonic adenocarcinoma, and a noncancerous Chinese hamster ovary cell line. Viability was significantly shortened in cancer cells exposed to aglycones: limonin, nomilin, obacunone, and deacetylnomilin. SH-SY5Y cells were more sensitive than Caco-2 cells to the limonoids, whereas noncancerous CHO cells showed hardly any change in cell numbers or morphology. Aglycone toxicity was dose-dependent but below the killing potential of glucosides.
None of the isolated compounds from yuzu seeds exhibited significant anti-proliferative activity against the human glioblastoma cell lines T98G and U-251 MG in at least one study, indicating that findings are compound- and cancer-type-specific.
Evidence strength: Preclinical (in vitro) only. No human clinical trials on yuzu and cancer outcomes have been identified. Results are preliminary and warrant further investigation.
The limonoid glucoside fraction of yuzu seed husk identified nomilin as a novel tyrosinase inhibitor. Tyrosinase inhibitory activity and noncompetitive inhibition assays and docking studies were performed to determine nomilin binding sites, and the antioxidative mechanism and antimelanogenic activity of nomilin were evaluated in B16F10 melanoma cells. The concentration of nomilin that did not show toxicity was <100 µg/mL.
Researchers prepared and characterized a callus extract from Citrus junos and assessed its utility as a source of topical anti-aging ingredients; callus extract was produced by aqueous extraction from Citrus junos grown on Murashige and Skoog medium. After measuring the total phenolic and flavonoid contents, the major phenolic compound in calli was identified as p-hydroxycinnamoylmalic acid.
Evidence strength: Skin-related effects are demonstrated only in cell-based experiments. No human clinical trials for yuzu in skin whitening or anti-aging applications have been identified in peer-reviewed literature.
Research demonstrated that treatment with limonoids or spermine (Spm) from yuzu seeds increased survival in Sandhoff disease (SD) mice. Investigations on the benefits of limonoids or Spm as natural compounds have revealed that they have antitumor, anti-inflammatory, and antioxidant properties, with spermine notably implicated in maintaining the intestinal mucosal barrier.
Although elucidation of the underlying mechanism is ongoing, researchers consider degeneration of the nervous system to be rooted in oxidative stress and inflammation. Given that diet is well known for moderating these phenomena, consuming limonoids and spermine may be effective at combatting or minimizing neurological damage.
Evidence strength: Preclinical (animal model of a rare lysosomal storage disease). No human data exist. Findings are very preliminary.
There are no established human therapeutic dosages for yuzu as a dietary supplement. The following dosages or concentrations were reported in specific research contexts:
No peer-reviewed human clinical trials defining optimal oral dosage ranges for yuzu extract, juice, or essential oil as a health supplement were identified.
At least one case of selective anaphylaxis to yuzu has been documented in the medical literature. Skin prick tests were positive with juice (8 mm) and peel (7 mm) of commercial yuzu, with juice of Citrus junos ICVN 0110241 (10 mm), and juice and pulp of one Citrus reticulata, while tests were negative to other citrus and ingested foods. A basophil activation test was positive with yuzu juice; at one-hundredth's dilution, the percentage of activated basophils was 13.4, with a positivity threshold of 5%. Specific IgE to lemon, orange, grapefruit, tangerine, mandarin, and other common allergens were negative (<0.10 kU/L); because ImmunoCap® to yuzu was not commercially available at the time, specific IgE to yuzu was detected by immuneblot.
The published case presents a selective food allergy to yuzu. This indicates that allergy specific to yuzu — independent of cross-reactivity with more common citrus fruits — is a documented possibility.
The yuzu seed fraction contains furanocoumarins. Among compounds isolated from yuzu seeds are three known furanocoumarins: (−)-heraclenol, (−)-byak-angelicin, and (+)-oxypeucedanin hydrate.
Some citrus essential oils — such as those from bergamot, lemon, and grapefruit — exhibit phototoxic effects upon exposure to sunlight/UV rays owing to furanocoumarins, especially 5-MOP (5-methoxypsoralen or bergapten). Removal of psoralen from citrus essential oil-containing formulations has been found to eliminate the possibility of phototoxicity.
Regarding yuzu specifically, the Tisserand Institute notes that expressed yuzu essential oil is classified among oils that may present phototoxic concerns. Cold-pressed citrus oils are more likely to retain furocoumarins than steam-distilled versions. While furocoumarins are found in many citrus fruits, not all contain furanocoumarins. Oils extracted from lemon and lime peel can be highly phototoxic while orange and tangerine are not.
The oral administration of yuzu methanol extract or hesperidin prolonged mouse tail vein bleeding time in a dose-dependent manner in vivo, suggesting that yuzu and hesperidin have anti-platelet activity. Although this has not been studied in human pharmacological trials, the antiplatelet activity of yuzu flavonoids — particularly hesperidin — raises a theoretical consideration in individuals already taking anticoagulant or antiplatelet medications. The Cosmetic Ingredient Review (CIR) report for citrus-derived ingredients notes that the 198 citrus-derived ingredients described function primarily as skin conditioning agents and fragrance; botanicals such as citrus are comprised of hundreds of constituents, some of which have the potential to cause toxic effects — for example, bergapten is a naturally occurring furanocoumarin in bergamot oil that causes phototoxicity.
In a 90-day sub-chronic and acute oral toxicity study on Sprague Dawley rats, hesperidin isolated from dehydrated citrus peel showed a low observed adverse effect level (LOAEL) at 1 g/kg, and a median lethal dose (LD50) of 4.83 g/kg, suggesting a good safety profile in animals; this concentration is much higher than the flavonoids administered in animal models (10–200 mg/kg) to obtain health benefits. Other citrus flavonoids, including nobiletin, tangeretin, and naringin, have also shown a good safety profile.
No human toxicity studies specific to yuzu extract or supplemental yuzu preparations were identified in the peer-reviewed literature. The overall evidence base for yuzu as a dietary supplement or therapeutic agent remains early-stage, with well-designed human clinical trials largely absent. Most mechanistic claims rest on in vitro and animal research, and the short-term human evidence is limited to aromatherapy contexts using inhaled essential oil.
Health conditions that Yuzu may help support.
Body systems that Yuzu may help support.
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