Parsley

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

Botany

Parsley is an annual herb indigenous to the Mediterranean region, but now cultivated worldwide with numerous varieties available. It has erect stems and non-hairy 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.1, 2, 3

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. The first, Aethusa cynapium (dog poison, fool's parsley, small hemlock) can be distinguished from parsley by the shiny yellow-green underside of the leaves, which are dull in parsley, and the white flowers, which are yellowish in parsley. Similarly, collectors should be aware of Conium maculatum (poison hemlock, water hemlock, poison parsley) and Cicuta maculata (water hemlock). 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 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.4

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 ailments. Parsley oil has also been used to regulate menstrual flow in the treatment of amenorrhea and dysmenorrhea, and is purported to be an abortifacient. Bruised leaves have been used to treat tumors, insect bites, lice, skin parasites, and contusions.5, 6 Parsley tea at one time was used to treat dysentery and gallstones.5 Other traditional uses reported include treatment of diseases of the prostate, liver, and spleen, in the treatment of anemia, arthritis, and cancers, as an expectorant, antimicrobial, aphrodisiac, hypotensive, laxative, and as a scalp lotion to stimulate hair growth.5, 7

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 such as phencyclidine.8

Chemistry

The concentration of parsley oil varies throughout the plant. The roots contain 0.1% oil, whereas the leaf contains about 0.3%.9 The fruit contains the largest percentage of oil, between 2% to 7%.9 The oil contains 2 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 and their relative content of apiol and myristicin vary. For example, "German" parsley oil contains about 60% to 80% apiol, whereas "French" parsley oil contains less apiol but more (50% to 60%) myristicin.10 Parsley has a high carotenoid content, with 25.7 mg per 100 g edible portion.11, 12

Parsley contains psoralen and related compounds that can induce photosensitivity (see Toxicology); these include ficusin, bergapten, majudin, and heraclin.13 The plant also contains several antimicrobial furocoumarins: psoralen, 8-methoxypsoralen, 5-methoxypsoralen, oxypeucedanin, and isopimpinellin.14 Parsley contains the estrogenic flavone glycosides, 6'-acetylapiin and petroside.15

Nutritionally, parsley is a good natural source of vitamins and minerals, including calcium, iron, carotene, ascorbic acid, and vitamin A.5, 9

Uses and Pharmacology

Antiplatelet activity

Animal data

Flavonoids apigenin and cosmosiin extracted from parsley, as well as the aqueous extract, showed antiplatelet activity in vitro and in rodents.16, 17, 18

Clinical data

Research reveals no clinical data regarding the use of parsley for antiplatelet activity.

Cancer

Animal data

Cytotoxicity and apoptotic activity has been demonstrated in vitro using human cancer cell lines, possibly by antioxidant activity.15, 19, 20, 21, 22

Clinical data

Research reveals no clinical data regarding the use of parsley or its extracts in cancer. An older clinical study evaluated the antioxidant effect of dietary parsley finding a pro-oxidant effect.17

Diuretic/laxative

Animal data

Apiol and myristicin may be responsible for the mild diuretic effect of the seed and oil.23 Rats given an aqueous parsley seed extract in place of drinking water eliminated a higher volume of urine compared with controls.24 An in situ kidney perfusion technique also supports this finding.24 Research suggests that the diuretic effect of parsley is mediated through an inhibition of the Na+-K+ pump.24 The laxative effect of parsley seed extract is also attributed to the inhibition of sodium and of the Na+-K+ pump.25

Clinical data

A small (n=20) clinical study on the effect of parsley tea found no effect on urinary indices measured including urine volume, pH, sodium, potassium, chloride, urea, creatinine, phosphorus, magnesium, uric acid, cystine, or citric acid content.26

Other uses

A review of in vitro studies on parsley and parsley extracts reports various effects including antimicrobial17, 27, 28 and immunosuppressive activity,17, 29 as well as spasmolytic effects.17 However, clinical trials are lacking to support any therapeutic recommendations.

Dosing

Parsley leaf has been used at daily doses of 6 g5; however, no clinical studies have been found that support this dose. The essential oil should not be used because of toxicity.30

Pregnancy / Lactation

GRAS when used as food. Safety and efficacy for dosages above those in foods are unproven and should be avoided. Emmenagogue and abortifacient effects may occur with higher doses.31

Interactions

Studies in rodents suggest parsley and its extracts may exert an antiplatelet effect. Although case reports are lacking, a theoretical interaction exists with other antiplatelet medicines.16, 17, 18

Parsley juice may alter the activity of drugs affected by the cytochrome P450.32

Adverse Reactions

Adverse effects from the use of parsley are uncommon. Individuals allergic to other members of the Apiaceae family (ie, carrot, fennel, celery) may be especially sensitive to the constituents in the flowers of parsley.30, 33

Because of the potential uterotonic effects, parsley oil, juice, and seed should not be taken by pregnant women. Adverse effects from the ingestion of the oil have included headache, giddiness, loss of balance, convulsions, and renal damage.5, 30

The psoralen compounds found in parsley have been linked to a photodermatitis reaction found among parsley cutters. The skin reaction is usually only evident if the areas that have contacted the juice are exposed to very strong sunlight; it can be minimized by the use of protective clothing and sunscreens.34

Toxicology

Parsley itself has FDA GRAS status; although, parsley fruit (seed) has been used traditionally as an abortifacient.3 Parsley extracts contain apiol and myristicin, chemical constituents with associated potential toxicities. The essential (pure) oil is toxic, with case reports of mortality.5, 30

References

Disclaimer

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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