Asparagus

Scientific Name(s): Asparagus officinalis L.
Common Name(s): Garden asparagus

Medically reviewed by Drugs.com. Last updated on Oct 8, 2024.

Clinical Overview

Use

Asparagus stalks are commonly consumed as a vegetable. Asparagus has been studied for its diuretic, hypoglycemic, antihypertensive, hypocholesterolemic, CNS, and antioxidant effects; however; there is little to no clinical evidence to support these uses. Other species, such as Asparagus racemosus, have been used in traditional Chinese and Ayurvedic medicine but are not reviewed in this monograph.

Dosing

There is insufficient clinical evidence to provide dosing recommendations for asparagus. A maximum dosage of 2,400 mg daily of dried asparagus root (in divided doses) as part of a combination preparation with parsley (Asparagus-P) has been evaluated for its antihypertensive effects; however, adverse reactions led to participant withdrawal from the study.

Contraindications

Contraindications have not been identified.

Pregnancy/Lactation

Asparagus has "generally recognized as safe" (GRAS) status when used as food. Avoid dosages above those found in food because safety and efficacy have not been established.

Interactions

None well documented.

Adverse Reactions

Symptoms of allergy to asparagus, including rhinitis, occupational asthma, oral allergic syndrome, allergic contact dermatitis, and anaphylaxis, are well documented. Exacerbation of gout has been reported with excessive consumption.

Toxicology

No data.

Scientific Family

• Liliaceae

Botany

Asparagus is a dioecious, perennial herb native to Europe and Asia and is widely cultivated. It has scale-like leaves and an erect, multibranched stem that grows up to 3 m in height. The aerial stems or spears arising from rhizomes are consumed as a vegetable. The fleshy roots and, to a lesser degree, seeds have been used for medicinal purposes.Leung 1980, USDA 2018 See also the related Wild Asparagus (Asparagus racemosus) monograph.

History

The genus Asparagus includes approximately 300 species.Negi 2010 Asparagus spears are widely used as a vegetable and are frequently blanched before consumption. Extracts of the seeds and roots have been used in alcoholic beverages, with average maximum levels of 16 ppm. The seeds have been used in coffee substitutes, diuretic preparations, laxatives, and remedies for neuritis and rheumatism, as well as to relieve toothache, stimulate hair growth, and treat cancer. The root possesses most of the diuretic effects.Negi 2010 It has been suggested that extracts possess some contraceptive effects. Home remedies have included topical application of preparations containing the shoots and extracts to cleanse the face and dry acneform lesions. Other asparagus species, such as A. racemosus, have been used in traditional Chinese and Ayurvedic medicine but are not reviewed in this monograph.Leung 1980

Chemistry

Asparagus roots contain inulin and several fructo-oligosaccharides. Two glycoside bitter principles, officinalisins I and II, were isolated from dried roots in yields of 0.12% and 0.075%. Other root components are beta-sitosterol, steroidal glycosides (asparagosides A to I, in order of increasing polarity), and steroidal saponins. The shoots contain sulfur-containing acids (asparagusic, dihydroasparagusic, and S-acetyldihydroasparagusic), alpha-amino-dimethyl-gamma-butyrothetin, a glycoside bitter principle different from those in the roots), and flavonoids (rutin, quercetin, and kaempferol), as well as asparagine, arginine, tyrosine, sarsasapogenin, beta-sitosterol, succinic acid, and sugars.Huang 2008, Leung 1980, Yamamori 2002 Asparagusic acid, found in the roots, and its derivatives are suggested to inhibit plant growth and possess nematocidal properties.USDA 2018 Phytoestrogens, including the isoflavone daidzein and a lignin, have been described,Horn-Ross 2000 as well as the phenols p-hydroxybenzoic, p-coumaric, gentisic, and ferulic acids.Yeh 2005 Following solid-liquid extraction processes, antioxidant compounds in A. officinalis were identified as ferulic acid, kaempferol, quercetin, rutin, and isorhamnetin.Fan 2015 Asparagus seeds contain large quantities of sodium hydroxide–soluble polysaccharides consisting of linear chains of beta-glucose and beta-mannose in a 1:1 ratio, 1 to 4 linked to alpha-galactose as a terminal group.Leung 1980 The seeds also contain 3 ribosome-inactivating proteins in concentrations of 8 to 400 mg per 100 g of starting material. These proteins, with molecular weights of approximately 30,000, have alkaline isoelectric points and inhibit protein synthesis in rabbit reticulocyte lysate assays.Stirpe 1983

Asparagus stalks contain few calories, fat, or cholesterol and are a good source of fiber, potassium, rutin, and folate. Folate conjugates, asparagusate dehydrogenase I and II, as well as lipoyl dehydrogenase have also been described.Leichter 1979, Rampersaud 2003 Stalks may contain residues of the insecticide permethrin and other herbicides.George 1985, Goewie 1985

Uses and Pharmacology

Anticancer effects

Anticancer effects of A. officinalis have primarily been noted in hepatocellular carcinoma cell lines.

Animal and in vitro data

Chemical constituents of asparagus, such as steroidal saponins, have been evaluated in vitro for activity against human and animal cancer cell lines.Edenharder 1990, Huang 2008, Kim 2009, Sati 1985 In one in vitro study, asparagus saponins caused apoptosis in the human hepatoma cell line HepG2; this occurred in a dose-dependent fashion, and apoptosis occurred through a mitochondrial-mediated and caspase-dependent pathway.Ji 2012 Another study determined that asparanin A, a steroidal saponin derived from A. officinalis, was effective in HepG2 cells through induction of G₂/M phase arrest, causing apoptosis.Liu 2009 Antitumor effects were noted with asparanin A in an in vitro and in vivo model.Li 2017 The deproteinized asparagus polysaccharide constituent exerted selective cytotoxic activity against hepatocellular carcinoma Hep3B and HepG2 cell lines. It was also found to potentiate the effects of mytomycin both in vitro and in vivo, and may be a chemosensitizer in the treatment of liver cancer.Xiang 2014

In another study, the chloroform fraction of A. officinalis exerted cytotoxic activity against breast cancer (MCF7), hepatocellular carcinoma (HEPG2), cervical cancer (HELA), and human normal melanocyte (HFB4) cell lines. The n-butanol fraction showed moderate activity against the MCF7 cell line.Almehdar 2012

The inedible bottom part of asparagus spears caused a concentration-dependent suppression of cell viability in breast, colon, and pancreatic cancers. It was found to modulate the Rho GTPase signaling pathway, which may contribute to its anticancer effects.Wang 2013

Antihypertensive effects

Although data are weak regarding asparagus' antihypertensive effects, it is believed to lower blood pressure through its diuretic and/or angiotensin-converting enzyme (ACE)–inhibitory effects.

Animal and in vitro data

In a 10-week study of spontaneously hypertensive rats, dietary consumption of asparagus 5% lowered systolic blood pressure, urinary protein excretion, and ACE activity compared with a normal diet. Additionally, creatinine clearance was higher in the group receiving a diet containing asparagus. ACE inhibitory activity was noted in a boiling water extract of asparagus; the ACE inhibitor isolated was identified as 2"-hydroxynicotianamine (an N-containing metabolite).Sanae 2013 Nicotianamine, another N-containing metabolite, has also been suggested to exert ACE inhibitory activity, and more recently, the S-metabolite asparaptine was discovered to have notable ACE inhibitory activity.Nakabayashi 2015

Clinical data

Effectiveness and tolerability of a combination preparation of asparagus and parsley (Asparagus-P) in patients requiring antihypertensive treatment were evaluated in a study using a maximal dosage of the product. Decreases in blood pressure were observed in some participants, but the study was not designed to evaluate this effect and changes could not confidently be attributed to Asparagus-P.Chrubasik 2006 A 6-week surveillance study conducted in 163 patients by the same group of investigators found that Asparagus-P did not have any impact on 24-hour ambulatory blood pressure measurements. Some cardiovascular measures improved slightly in the per-protocol group; however, the intention-to-treat analysis did not show any changes.Chrubasik 2009

Anti-inflammatory activity

In vitro data

In vitro activity against cyclooxygenase 2 has been described.Jang 2004

Antioxidant activity

In vitro data

Free radical scavenging antioxidant activity attributed to the phenolic content of asparagus has been described.Dartsch 2008, Dartsch 2008, Yeh 2005

CNS effects

Animal data

In a murine model, A. officinalis improved cognitive impairment caused by scopolamine. It also caused an increase in acetylcholine and inhibited the acetylcholinesterase enzyme.Sui 2017

Clinical data

In healthy adult men, enzyme-treated asparagus extract enhanced HSP70 mRNA expression compared with placebo. Additionally, asparagus modulated sleep in men with low sleep efficiency or excessive sleep time. Serum and salivary cortisol levels did not change in the asparagus group but increased in the placebo group.Ito 2014 In a study evaluating the effects of enzyme-treated asparagus extract on stress response in healthy volunteers, the extract improved 2 mood states (depression/dejection and fatigue), as well as increased the number of answers and number of accurate answers provided on a stressful arithmetic test (Uchida-Kraepelin). The authors suggested the beneficial effects on stress management associated with asparagus may suggest the potential for use in improving office work performance.Takanari 2016

Ethanol metabolism

In vitro data

In a study using rat enzymes, extracts from the leaves and shoots of A. officinalis upregulated alcohol dehydrogenase and aldehyde dehydrogenase, enzymes responsible for the metabolism of alcohol, suggesting a potential role in the alleviation of alcohol-induced hangover.Kim 2009

GI effects

Animal and in vitro data

Effects on human intestinal bacteria have been described.Yamamori 2002 In a study of rats, both cooked whole asparagus and its purified flavonoid glycoside rutin attenuated the effects of colonic tissue damage and disease severity in dextran sodium sulfate–induced colitis.Power 2016

Hypocholesterolemic effects

Animal data

In a study of hypercholesterolemic rats, 5 weeks of treatment with lyophilized asparagus, fiber fraction of asparagus, and flavonoid fraction of asparagus produced cholesterol-lowering effects.Vázquez-Castilla 2013 Similar findings were also noted in a study of mice receiving 8 weeks of an n-butanol extract (varying doses of 40, 80, and 160 mg/kg) of A. officinalis. Reductions in total and low-density lipoprotein cholesterol were noted, as well as a significant increase in high-density lipoprotein cholesterol levels.Zhu 2011 In another study, an aqueous extract of the inedible bottom part of A. officinalis spears reduced triglyceride levels in streptozotocin-induced diabetic rats.Zhao 2011

Hypoglycemic effects

Animal and in vitro data

In a study of streptozotocin-induced diabetes in rats, the aqueous extract of the inedible bottom portion of A. officinalis spears administered for 21 days reduced fasting glucose levels but was also associated with a notable increase in body weight and hepatic glycogen levels.Zhao 2011 In a similar study, A. officinalis at dosages of 250 mg/kg and 500 mg/kg for 28 days caused a dose- and time-dependent reduction in glucose levels. The higher dose was also associated with an improvement in insulin levels.Hafizur 2012

Dosing

There is insufficient clinical evidence to provide dosage recommendations for asparagus. The commercial product Asparagus-P contains 200 mg of pulverized dried asparagus root and 200 mg of dried parsley leaves per tablet.Chrubasik 2006, Dartsch 2008, Dartsch 2008 Asparagus-P administered as 4 tablets 3 times/day (maximum dosage of 2,400 mg daily of dried asparagus root) for a target of 6 weeks has been evaluated for its antihypertensive effects; however, adverse reactions led to participant withdrawal from the study.Chrubasik 2006

Pregnancy / Lactation

Asparagus has GRAS status when used as food. Avoid amounts above those found in food because safety and efficacy have not been established. Asparagus root extract increased serum levels of gonadotropin-releasing hormone, follicle-stimulating hormone, luteinal hormone, estrogen, and progestin hormones in a study in rats. Additionally, there was an increase in the number of ovarian follicles and corpus luteum in rats receiving asparagus.Karimi Jashni 2016

Interactions

None well documented.Izzo 2001

Adverse Reactions

Few clinical trials exist to report adverse reactions. At maximum recommended dosages (12 tablets daily) of Asparagus-P (containing 200 mg of pulverized dried asparagus root and 200 mg of dried parsley leaves per tablet), renal pain, peripheral edema, and skin allergies have been reported.(Chrubasik 2006) Asparagus is considered a high-purine–containing vegetable and may exacerbate gouty symptoms.(Chrubasik 2006, Zgaga 2012) Symptoms of allergy to asparagus, including rhinitis, occupational asthma, oral allergic syndrome, allergic contact dermatitis, fixed food eruptions, and anaphylaxis, are well documented in the literature. Lipid transfer proteins, profilin, and glycoproteins may account for adverse reactions as well as for cross-sensitivities.(Díaz-Perales 2002, Gaus 2014, Pajno 2002, Rieker 2004, Tabar 2004, Volz 2005) Despite suggestions that asparagus is a dietary cause of gout, clinical evidence is limited.(Chrubasik 2006) A phytobezoar of asparagus that led to small bowel perforation was reported in a 33-year-old woman after she consumed significant amounts of asparagus during the previous year.(Parr 2020)

Ingestion of asparagus spears produces a characteristic pungent odor in the urine of some individuals within a few hours of consumption, which may be due to the production of sulfur-containing alkyl compounds from precursor chemical constituent compounds found in asparagus.(Mitchell 2001, Richer 1989, Waring 1987, White 1975) Debate on the issue remains, with some researchers suggesting a genetic predisposition to both the production of and/or sensing the odor.(Lison 1980, Mitchell 1987, Mitchell 2001, Sugarman 1985)

Toxicology

Reports exist of botulism poisoning following the ingestion of improperly home-preserved asparagus.Abgueguen 2003, Paterson 1992 The median lethal dose (LD₅₀) of enzyme-treated asparagus extract was determined to be greater than 2 g/kg in a study in rats. In the 90-day subchronic arm of this study, enzyme-treated asparagus extract in doses of 0.5, 1, and 2 g/kg were not associated with changes in food consumption, body weight, mortality, urinalysis (except an increase in protein excretion with the 2 g/kg dose), hematology (except for increased activated partial thromboplastin time in the 2 g/kg group and decreased mean corpuscular hemoglobin concentration in the 1 g/kg group), biochemistry, necropsy, organ weight, and histopathology.Ito 2014

References

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