Parsley

Scientific Name(s): Petroselinum crispum (Mill.) Nyman ex A. W. Hill.
Common Name(s): Garden parsley, Parsley, Rock parsley

Medically reviewed by Drugs.com. Last updated on Mar 22, 2024.

Clinical Overview

Use

Parsley is a source of certain vitamins and minerals that has traditionally been used for a variety of conditions. Limited in vitro or animal studies suggest that parsley has antiplatelet, antidiabetic, antiurolithiasis, diuretic, antimicrobial, immunosuppressive, and spasmolytic effects. Clinical studies suggest reductions in incidence of melasma. However, clinical trial data are lacking to recommend use for any indication.

Dosing

Clinical data are lacking to provide dosing recommendations. Parsley has generally recognized as safe (GRAS) status when used as food, according to the US Food and Drug Administration (FDA).

Contraindications

Contraindications have not been identified.

Pregnancy/Lactation

Parsley has GRAS status when used as food. Amounts greater than those used in foods should be avoided, as safety and efficacy are unproven. Emmenagogue and abortifacient effects may occur with higher doses.

Interactions

Parsley may increase the serum concentration of sirolimus.

Adverse Reactions

Parsley has GRAS status when used as food. Adverse effects from ingestion of parsley oil include headache, giddiness, loss of balance, convulsions, and renal damage.

Toxicology

While no major toxicities have been reported, parsley should not be taken during pregnancy because of possible uterotonic effects.

Scientific Family

• Apiaceae (carrot)

Botany

Parsley is an annual herb indigenous to the Mediterranean region but cultivated worldwide, with numerous varieties available. It has erect stems and nonhairy bright green leaves. Parsley produces an umbel of tiny flowers and characteristic ribbed fruit ("seeds"). Parsley seed oil and herb oil are obtained from the above-ground plant parts by steam distillation, while the dried leaf flakes are sold commercially as a culinary herb.(Chevallier 1996, Khan 2010, USDA 2022)

Caution must be used when gathering wild parsley because of the general similarity of its leaves and flowers to those of 3 common poisonous plants: Aethusa cynapium (dog poison, fool's parsley, small hemlock); Conium maculatum (poison hemlock, water hemlock, poison parsley); and Cicuta maculata (water hemlock). A. cynapium can be distinguished from parsley by its shiny yellow-green underside of the leaves (dull in parsley) and white flowers (yellowish in parsley). Poison hemlock is a much larger plant than common parsley. Poisonings have occurred when the leaves of Conium were mistaken for parsley and the seeds for anise. Symptoms of Conium and Cicuta poisoning include vomiting, diarrhea, weakness, paralysis, weak pulse, dilated pupils, convulsions, and death.

History

Parsley leaves and roots are popular as condiments and as a garnish worldwide. In Lebanon, parsley is a major ingredient in the national dish called tabbouleh. An average adult may consume as much as 50 g of parsley per meal.(Zaynoun 1985)

Parsley seed was used traditionally as a carminative to decrease flatulence and colic pain. The root was used as a diuretic and the juice to treat kidney conditions. Parsley oil has been used to regulate menstrual flow in the treatment of amenorrhea and dysmenorrhea; the oil also purportedly has abortifacient properties. Bruised leaves have been used to treat tumors, insect bites, lice, skin parasites, and contusions.(Duke 2002, Meyer 1934) Parsley tea was used to treat dysentery and gallstones.(Duke 2002) Other reported traditional uses include treatment of diseases of the prostate, liver, and spleen; treatment of anemia, arthritis, and cancers; as a scalp lotion to stimulate hair growth; and use for its expectorant, antimicrobial, aphrodisiac, hypotensive, and laxative effects.(Duke 2002, Hoffman 1988)

Myristicin, a compound found in parsley oil, is suggested to be in part responsible for the hallucinogenic effect of nutmeg. It is not known whether parsley oil induces hallucinations, but the practice of smoking parsley as a cannabis substitute was well known during the 1960s. Parsley may have been smoked for a euphoric effect or as a carrier for more potent drugs (eg, phencyclidine).(Cook 1982)

Warm compresses or poultices of parsley have been used to treat breast engorgement and mastalgia. In addition, oral capsules containing sage and parsley capsules are said to decrease milk flow; however, no scientifically valid clinical trials support this use.(Kabiri 2017, NLM 2021)

Chemistry

The concentration of parsley oil varies throughout the plant, with the roots containing 0.1% oil and the leaf containing about 0.3%.(Tyler 1988) The fruit contains the largest percentage of oil, between 2% to 7%.(Tyler 1988) The oil contains 2 major components, apiol and myristicin, which are pharmacologically active. Myristicin is chemically related to apiol and has also been identified in nutmeg. More than 30 varieties of parsley are recognized; relative content of apiol and myristicin varies. For example, "German" parsley oil contains about 60% to 80% apiol, whereas "French" parsley oil contains less apiol but more (50% to 60%) myristicin.(Tyler 1987) Parsley has a high carotenoid content (25.7 mg per 100 g of the edible portion).(Daly 2010, Mueller 1997)

Parsley contains psoralen and other related compounds that can induce photosensitivity (see Toxicology); these include ficusin, bergapten, majudin, and heraclin.(Pathak 1962) The plant also contains several antimicrobial furocoumarins: psoralen, 8-methoxypsoralen, 5-methoxypsoralen, oxypeucedanin, and isopimpinellin.(Manderfeld 1997) In addition, parsley contains the estrogenic flavone glycosides 6'-acetylapiin and petroside, as well as flavonoids (eg, apigenin, cosmosiin).(Yoshikawa 2000)

Nutritionally, parsley is a natural source of vitamins and minerals, including calcium, iron, carotene, ascorbic acid, and vitamin A.(Duke 2002, Tyler 1988)

Uses and Pharmacology

Antiplatelet activity

Animal and in vitro data

The flavonoids apigenin and cosmosiin extracted from parsley, as well as from a P. crispum aqueous extract, showed antiplatelet activity in vitro and in rodents.(Chaves 2011, Farzaei 2013, Gadi 2012)

Cancer

Apigenin reportedly has protective effects against a wide variety of cancers. Apigenin is a parsley compound known to possess pro-oxidant effects.(Oyenihi 2022) According to recent literature, apigenin is able to reduce cancer cell glucose uptake, inhibit remodeling of the extracellular matrix, inhibit cell adhesion molecules that participate in cancer progression, and hinder the development of blood vessels needed by growing tumors.(Kowalczyk 2017) Several studies have demonstrated that the anticarcinogenic properties of apigenin occur through regulation of cellular response to oxidative stress and DNA damage, suppression of inflammation and angiogenesis, retardation of cell proliferation, and induction of autophagy and apoptosis. One of the most well-recognized mechanisms of apigenin is the capability to promote cell cycle arrest and induction of apoptosis through the p53-related pathway.(Sung 2016)

Animal data

Cytotoxicity and apoptotic activity have been demonstrated in vitro using human cancer cell lines, possibly due to antioxidant activity.(Dorman 2011, Farshori 2013, Farshori 2014, Tang 2015, Yoshikawa 2000)

COVID-19

Clinical data

In a study aiming to establish an evidence-based dietary protocol for hospitalized patients with acute respiratory infectious disease caused by COVID-19, meals containing various medicinal herbs and foods were evaluated in a clinical trial. Parsley was included as part of the proposed diet because it was believed to dilute lung secretions and reduce cough.(Moslemifard 2020)

Diabetes

Animal data

Parsley extract has been shown to reverse hyperglycemia and protein glycation associated with diabetes in several organ systems. Parsley extract orally administered to rats with streptozotocin-induced diabetes lowered circulating glucose after 28 days.(Bower 2016) The mechanism for the antidiabetic action of parsley extract may be inhibition of glucose absorption by inhibition of alpha-glucosidase.(Bower 2016)

Diuretic/Laxative effects

Apiol and myristicin may be responsible for the mild diuretic effect of parsley seed and oil.(Farzaei 2013) Research suggests that the diuretic effect of parsley is mediated through an inhibition of the Na+-K+ pump.(Kreydiyyeh 2002) The laxative effect of parsley seed extract is also attributed to the inhibition of sodium and the Na+-K+ pump.(Kreydiyyeh 2001)

Animal and in situ data

Rats given an aqueous parsley seed extract in place of drinking water eliminated a higher volume of urine compared with the relative controls. An in situ kidney perfusion technique also supports this finding.(Kreydiyyeh 2002)

Clinical data

A small clinical study in healthy volunteers (N=20) to evaluate the effects of parsley tea on urinary composition and urinary stone risk factors showed no effect on urinary indices measurements, including urine volume, pH, sodium, potassium, chloride, urea, creatinine, phosphorus, magnesium, uric acid, cystine, or citric acid content.(Alyami 2011)

Melasma

Compounds with antioxidant properties (eg, parsley) have been used in combination with other antioxidants to treat melasma, a chronic condition of skin hyperpigmentation. Although there is conflicting evidence regarding their therapeutic efficacy, these naturally occurring substances potentially offer promising alternative therapeutic options.(Babbush 2021)

Clinical data

In a small, double-blind, randomized, clinical trial of patients with epidermal melasma (N=27), effects of topical P. crispum on reduction of epidermal melasma were compared with hydroquinone cream. In the case group, participants were given 20 g of parsley powdered and packed. To avoid spoiling the brew, the participants were advised to brew 2.5 g of the powdered parsley in a cup [125 mL] of hot water, then filter the brew and keep it in a sealed glass container for 6 days every week. The brewed parsley was then applied to participant facial dark spots with a piece of cotton. The control group applied a thin layer of hydroquinone 4% cream to their facial dark spots every night at bedtime and washed it in the morning. Mean severity of melasma after intervention was not significantly different between the 2 treatment groups. However, the study was small, with limited robust results.(Khosravan 2017)

Renal disease

Animal data

Parsley and its extracts have been used as a potential complementary or alternative treatment for various renal diseases. P. crispum has been used as an antiurolithiasis agent. A parsley ethanolic extract prevented the nucleation and precipitation of calcium oxalate, urine supersaturation, and urinary protein excretion in a rat model of calcium stone formation. Parsley was also effective in regulating urinary pH at a value at which calcium oxalate crystals could be maintained as dispersed particles and the elimination of these crystals could be facilitated.(Nirumand 2018)

Other uses

A review of in vitro studies on parsley and parsley extracts reports various effects, including antimicrobial(Farzaei 2013, Petrolini 2013, Wahba 2010) and immunosuppressive activity,(Farzaei 2013, Karimi 2012) as well as spasmolytic effects.(Farzaei 2013)

Dosing

Clinical data are lacking to provide dosing recommendations. Parsley has GRAS status when used as food, according to the FDA.(FDA 2022)

Pregnancy / Lactation

Parsley has GRAS status when used as food. Amounts greater than those used in foods should be avoided, as safety and efficacy are unproven. Emmenagogue and abortifacient effects may occur with higher doses.(Ernst 2002, FDA 2022)

Interactions

Sirolimus: Parsley may increase the serum concentration of sirolimus. Monitor therapy.(Jakovljevic 2002, Kurtaran 2021)

Adverse Reactions

Adverse effects with use of parsley are uncommon. Individuals allergic to other members of the Apiaceae family (ie, carrot, fennel, celery) may also be especially sensitive to the constituents in parsley flowers.(Blumenthal 2000, Foti 2011)

Because of the potential uterotonic effects, parsley oil, juice, and seeds should not be taken during pregnancy. Adverse effects from ingestion of the oil have included headache, giddiness, loss of balance, convulsions, and renal damage.(Blumenthal 2000, Duke 2002)

The psoralen-related compounds found in parsley have been linked to photodermatitis reactions among parsley cutters. These skin reactions are usually only evident if the areas that had contact with the juice are exposed to very strong sunlight; photodermatitis can be minimized by using protective clothing and sunscreens.(Smith 1985)

Toxicology

Parsley has FDA GRAS status; however, parsley fruit (seed) reportedly has abortifacient properties.(Khan 2010) The parsley extract chemical constituents apiol and myristicin are associated with potential toxicities. The essential (pure) oil is toxic, with various case reports of mortality cited.(Blumenthal 2000, Duke 2002)

References

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This information relates to an herbal, vitamin, mineral or other dietary supplement. This product has not been reviewed by the FDA to determine whether it is safe or effective and is not subject to the quality standards and safety information collection standards that are applicable to most prescription drugs. This information should not be used to decide whether or not to take this product. This information does not endorse this product as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this product. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this product. This information is not specific medical advice and does not replace information you receive from your health care provider. You should talk with your health care provider for complete information about the risks and benefits of using this product.

This product may adversely interact with certain health and medical conditions, other prescription and over-the-counter drugs, foods, or other dietary supplements. This product may be unsafe when used before surgery or other medical procedures. It is important to fully inform your doctor about the herbal, vitamins, mineral or any other supplements you are taking before any kind of surgery or medical procedure. With the exception of certain products that are generally recognized as safe in normal quantities, including use of folic acid and prenatal vitamins during pregnancy, this product has not been sufficiently studied to determine whether it is safe to use during pregnancy or nursing or by persons younger than 2 years of age.

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