Asparagus / Asperge

Asperge bij Dodoens

"Die ionghe scuetkens van Coraelcruyt ghesoden ende met olie ende azijn gegheten / doen water maken / ende sijn goet tseghen die droppelpisse ende doen saechten camerganck hebben."

Dodoens kende het woord asperge onder de vormen Asparagus, Speragus en Sparagus, maar als dagelijkse benaming voor asperge gebruikte hij het woord Coraelcruyt. Dat woord zou zijn oorsprong hebben in de rode kleur van de bessen die aan de sierlijke uiteinden van de plant bengelen. De wilde asperge werd in de tijd van Dodoens in Bourgondië en Duitsland gevonden.

Bij ons kwam asperge in de tijd van Dodoens alleen voor bij kruidenliefhebbers, wat in wezen zou moeten betekenen dat de plant nog niet algemeen als groente bekend was. Toch werd bij Dodoens al vermeld dat de "sceutkens", die in april boven de grond kwamen, werden gekookt en met olie en azijn gegeten. Naast de gekende aspergevorm uit de tuinen, vond hij ook een wilde aspergesoort (Asparagus acutifolius).

Volgens Dodoens groeide asperge in steenachtige, leem-achtige grond. Dit is een zeldzame vreemde vermelding uit die tijd en in tegenstelling met de teelttechniek uit de 20ste eeuw, want nu teelt men asperges immers in zandachtige grond met een lage grondwaterstand.

Teelt vroeger

Vandaag zijn er liggende en rechtgroeiende soorten. Asperge is een doorlevende plant die in cultuur wordt gebracht na het 3de of 4de jaar; vanaf dan gebeurt het oogsten elk jaar tot Sint-Jan (24 juni). Asperge werd al door Cato (234-149 v.Chr.) bij de Romeinen vermeld. Hij schrijft dat asperge werd gezaaid en pas na acht of negen jaar(!) werd uitgeplant om er vervolgens van te oogsten.

In de keuken

In 1554: Ze werden gekookt en met olie en azijn gegeten (Dodoens).

In 1608: "De ionge scheutkens van Coraelkruyt, Asperges genaamd, worden somtijts in het vleeschsop gesoden ende gegeten oft men siedtse alleen in Water, ende men eetse met Olie, Azijn ende wat Saut, als ander Salaet. Sij zijn aengenaem van smaeck: worden haest verteert oft verdouwt: en doen sachten camergangck hebben

Tot de verbeelding spreekt natuurlijk ook de penetrante geur die de urine krijgt na het eten van asperges. Volgens sommigen zou dit wijzen op een reinigende werking van asperges. Waarschijnlijker is dat deze geur vooral ontstaat door de afbraak van zwavelbestanddelen . Volgens sommige onderzoeken zou die stof methaanethiol zijn en of S-Methyl thioacrylate and S-methyl 3-(methylthio)thiopropionate.

Hedendaags medicinaal gebruik

Aspergeswortels zijn vooral bekend om hun diuretische werking, te gebruiken bij oedeem en blaasstenen. Het is ook een hulpmiddel bij vermageringskuren en heeft mogelijk een bloeddrukverlagende werking. Recenter zijn er FOS gevonden die een postitief effect op de darmflora kunnen hebben. In het verleden heeft Asparagus enige bekendheid gehad bij de behandeling van een kater, uit onderzoek blijkt nu dat asparagus de enzymen stimuleert die alcohol afbreken. De 'activities of 2 key enzymes that metabolize ethanol, alcohol dehydrogenase and aldehyde dehydrogenase, were upregulated by more than 2-fold in response to treatment with the leaf- and shoot extracts' aldus de conclusies van het onderzoek.

Verder is ook gebleken dat asperge een goede anti-oxydantwerking heeft, al is dat bijna vanzelfsprekend voor de meeste geneeskrachtige planten.

Voor verder onderzoek

Richer, Decker, Belin, Imbs, Montastruc, Giudicelli: "Odorous urine in man after asparagus", British Journal of Clinical Pharmacology, May 1989

The chemical nature of the urinary odour produced by man after asparagus ingestion.In: Xenobiotica (1987 Nov) 17(11):1363-71

Yamamori A, Onodera S, Kikuchi M, Shiomi N. Two novel oligosaccharides formed by 1F-fructosyltransferase purified from roots of asparagus ( Asparagus officinalis L.). Biosci Biotechnol Biochem . 2002;66(6):1419-1422.

Science. 1975 Sep 5;189(4205):810-11.Occurrence of S-methyl thioesters in urines of humans after they have eaten asparagus.White RH.

Complete Asparagus information from Drugs.com

Wetenschappelijk onderzoek asparagus

Kim BY, Cui ZG, Lee SR, Kim SJ, Kang HK, Lee YK, Park DB. Effects of Asparagus officinalis extracts on liver cell toxicity and ethanol metabolism. J Food Sci 2009 Sep; 74(7):H204-8.

Asparagus officinalis is a vegetable that is widely consumed worldwide and has also long been used as a herbal medicine for the treatment of several diseases. Although A. officinalis is generally regarded as a supplement for the alleviation of alcohol hangover, little is known about its effects on cell metabolism. Therefore, this study was conducted to analyze the constituents of the young shoots and the leaves of asparagus and to compare their biochemical properties. The amino acid and inorganic mineral contents were found to be much higher in the leaves than the shoots. In addition, treatment of HepG2 human hepatoma cells with the leaf extract suppressed more than 70% of the intensity of hydrogen peroxide (1 mM)-stimulated DCF fluorescence, a marker of reactive oxygen species (ROS). Cellular toxicities induced by treatment with hydrogen peroxide, ethanol, or tetrachloride carbon (CCl(4)) were also significantly alleviated in response to treatment with the extracts of A. officinalis leaves and shoots. Additionally, the activities of 2 key enzymes that metabolize ethanol, alcohol dehydrogenase and aldehyde dehydrogenase, were upregulated by more than 2-fold in response to treatment with the leaf- and shoot extracts. Taken together, these results provide biochemical evidence of the method by which A. officinalis exerts its biological functions, including the alleviation of alcohol hangover and the protection of liver cells against toxic insults. Moreover, the results of this study indicate that portions of asparagus that are typically discarded, such as the leaves, have therapeutic use.

Hasani-Ranjbar S, Nayebi N, Larijani B, Abdollahi M

A systematic review of the efficacy and safety of herbal medicines used in the treatment of obesity. [JOURNAL ARTICLE]

World J Gastroenterol 2009 Jul 7; 15(25):3073-3085.

This review focuses on the efficacy and safety of effective herbal medicines in the management of obesity in humans and animals. PubMed, Scopus, Google Scholar, Web of Science, and IranMedex databases were searched up to December 30, 2008. The search terms were "obesity" and ("herbal medicine" or "plant", "plant medicinal" or "medicine traditional") without narrowing or limiting search elements. All of the human and animal studies on the effects of herbs with the key outcome of change in anthropometric measures such as body weight and waist-hip circumference, body fat, amount of food intake, and appetite were included. In vitro studies, reviews, and letters to editors were excluded. Of the publications identified in the initial database, 915 results were identified and reviewed, and a total of 77 studies were included (19 human and 58 animal studies). Studies with Cissus quadrangularis (CQ), Sambucus nigra, Asparagus officinalis, Garcinia atroviridis, ephedra and caffeine, Slimax (extract of several plants including Zingiber officinale and Bofutsushosan) showed a significant decrease in body weight. In 41 animal studies, significant weight loss or inhibition of weight gain was found. No significant adverse effects or mortality were observed except in studies with supplements containing ephedra, caffeine and Bofutsushosan. In conclusion, compounds containing ephedra, CQ, ginseng, bitter melon, and zingiber were found to be effective in the management of obesity. Attention to these natural compounds would open a new approach for novel therapeutic and more effective agents.

Chrubasik C, Maier T, Dawid C, Torda T, Schieber A, Hofmann T, Chrubasik S

An observational study and quantification of the actives in a supplement with Sambucus nigra and Asparagus officinalis used for weight reduction. Phytother Res 2008 Mar 18.

The aim of the study was to obtain information on the content of co-active compounds of a food supplement recommended as a weight reduction diet and on its short-term effectiveness and safety as a starter for lifestyle change. Eighty participants completed the protocol. The Sambucus nigra L. berry juice enriched with flower extract and tablets containing berry powder and flower extract provided a total of 1 mg anthocyanins, 370 mg flavonol glycosides and 150 mg hydroxycinnamates per day; the Asparagus officinalis L. powder tablets provided 19 mg saponins per day. After the diet, the mean weight, blood pressure, physical and emotional well-being and the quality of life had significantly improved (ITT analysis). The effectiveness and tolerability of the regimen were rated as very good or good by most of the completers. It remains to be established if any particular compounds contribute to the efficacy of the diet. Copyright (c) 2008 John Wiley & Sons, Ltd.

Sun T, Powers JR, Tang J

Effect of enzymatic macerate treatment on rutin content, antioxidant activity, yield, and physical properties of asparagus juice. [Journal

J Food Sci 2007 May; 72(4):S267-71.

Asparagus is a vegetable with high antioxidant activity. In this research, asparagus juice was produced from fresh asparagus macerate treated with a carbohydrases mixture (Viscozyme) at 37 degrees C for up to 8 h. Rutin content, antioxidant activity, yield, soluble solid content, and color of the produced asparagus juice were determined. The results showed that Viscozyme significantly increased the yield of asparagus juice, especially in the 1st hour, which was higher than control (without Viscozyme treatment), but the juice had significantly less rutin content than control and had higher antioxidant activity than control only in the 1st 2 h. Juice with Viscozyme treatment had significantly higher soluble solid content than control. The greenness of asparagus juice deteriorates quickly for both the Viscozyme group and control. Viscozyme had advantage in producing juice with high yield, antioxidant activity, and soluble solid content in shorter time (2 h) of treatment compared to control.

Asperge - Van medicinaal tot delicatesse

Eindelijk verscheen een compleet boek over asperges. Voor de consument die een eigen aspergeveld wil aanleggen en zo ruim tien jaar achter elkaar zijn eigen asperges wil oogsten en voor de beroepsmatige teler, die zijn teelt wil perfectioneren. Piet Boonen beschrijft helder - en soms met Limburgse dialectwoorden, maar die wel door iedereen begrepen kunnen worden - alle ins en outs van de asperges.

Piet Boonen werkte 25 jaar bij de Proeftuin Noord-Limburg en hij was daar onderzoeker en veredelaar van asperges. Als zoon van een Limburgse agrariër keek hij onderweg naar school stiekem in kistjes die, afgedekt met krantenpapier, langs de weg stonden om naar de veiling gebracht te worden. Op de allerschraalste stuifzandgronden, waarop geen ander gewas wilde groeien, kon men nog wel asperges telen. Omdat zijn vader nog een hectare zandgrond had braak liggen, begon men daarop asperges aan te planten. En Piet kreeg daarover de supervisie, want hij zat op de tuinbouwschool.

Deze basis zorgde ervoor dat hij onderzoeker en veredelaar werd bij de proeftuin. Boonen beschrijft in dit boek zijn ervaringen met en zijn kennis over asperges en die is zeer uitgebreid. Eindelijk staat er in een boek in begrijpelijke taal informatie over de diverse rassen en over de ontwikkeling daarvan. Hij beschrijft de stappen in ontwikkeling van de Vroege van Argenteuille en de Roem van Brunswijk tot bijvoorbeeld de Gijnlim, de Backlim en natuurlijk het door hem ontwikkelde ras Boonlim. Ook buitenlandse rassen komen op deze manier aan bod.

Hij beschrijft - nog steeds in begrijpelijke taal - de eigenschappen van de rassen, de geschiedenis en de specifieke kenmerken daarvan in de koude grond, in kassen, met en zonder bodemverwarming en zo meer. De bodembehandeling, bodemmoeheid en (het voorkomen van) ziektes, de plantafstanden, de bemesting, opkweekmethoden, alles komt in dit boek aan bod.

Uiteraard geeft de auteur ook enkele recepten om asperges te bereiden. Dit boek is een aanrader voor wie meer wil weten over asperges.

Asparagus officinalis

Asparagus (Asparagus officinalis, Asparagaceae) is an herbaceous perennial with stalks that can grow to several feet in height. Most asparagus is harvested once the stalk reaches 6-8 inches in height. The stalk is the edible portion of the plant, along with its pointed, budlike tip.1,2 If asparagus is not harvested, the stalks grow into finely textured, fern-like plants before going dormant in winter.3 In the United States, the primary asparagus producers are the states of California, Washington, and Michigan.4

Depending on the cultivation method, asparagus yields a crop in one of three colors: green, white, or purple. Green asparagus, the most common in the US, is allowed to grow exposed to sunlight until harvested. White asparagus contains no chlorophyll due to human intervention, which involves mounding dirt on the stalk as it grows to shield it from sunlight.1 Purple asparagus, which contains anthocyanins, is allowed to grow only 1-2 inches above the soil before it is cut.5 Depending on the climate, most asparagus plants are harvested from late spring to early summer.1

Phytochemicals and Constituents

Asparagus is a nutrient-dense food with an abundance of vitamins and minerals and a low amount of calories. One cup of asparagus contains approximately 27 calories.2 Compared to other vegetables, asparagus is lower in carbohydrates and higher in protein.6

Asparagus contains high amounts of amino acids, including aspartic acid and asparagine. Aspartic acid helps counteract excess amounts of ammonia in the body, which can cause fatigue and low energy.5 Asparagine, a diuretic, breaks down oxalic and uric acid formations in the kidneys and muscles, so the byproducts may be eliminated through urine.

Asparagus is a good source of vitamins A, C, and E, as well as other antioxidant compounds, such as glutathione.3 Glutathione contains sulfur atoms, and is partially responsible for the sulfurous smell that asparagus releases during cooking. Glutathione, which the body naturally produces, supports a healthy immune system and liver, particularly in cases of chronic diseases, though research into these effects is ongoing.7,8

Plants in the genus Asparagus also contain saponins.9 Saponins exhibit a number of different properties in the human body, including antioxidant, immunostimulant, antihepatotoxic, antibacterial, antidiabetic, cytotoxic, and antimicrobial. The saponins present in asparagus lend a bitter characteristic to the plant’s taste and also contribute to its diuretic properties.10 While these compounds often have beneficial effects on humans, saponins from certain plant sources can be toxic to animals (which usually consume different saponin-containing plants, and in much higher quantities, than humans).

Historical and Commercial Uses

The genus Asparagus includes about 300 species. Native to northern Africa, Europe, and Asia, A. officinalis was first cultivated by the Egyptians, Greeks, and Romans. Since ancient times, asparagus has had a famous following, recorded as being offered to the gods of the ancient Egyptians,5 eaten by King Louis XIV of France,1 and the favorite vegetable of US President Thomas Jefferson.11 Since early cultivation, commercial asparagus is grown in subtropical and temperate climates including in the US, Mexico, Peru, France, Spain, and the Mediterranean region.2

Asparagus has been used traditionally for a variety of health benefits. In Europe and Asia, asparagus has been used medicinally as a diuretic and laxative, as well as a treatment for heart disease, hypertension, rheumatism, acne, infertility, eye problems, and menstrual cramps.3,11 The ancient Greeks and Romans used asparagus to alleviate pain from toothaches and bee stings.5 They also believed asparagus would help prevent and remove kidney stones by flushing out the kidneys.9 The phallic shape of asparagus contributed to its widespread use as an aphrodisiac, which has persisted well into modern times.12

Ayurvedic practitioners used asparagus species for their anti-inflammatory properties, which are attributed to the saponin constituents.3 In India, the root of shatavari (A. racemosus) has been used traditionally to treat infertility and menstrual cramping, and as a galactagogue (to stimulate breast milk production).9 Asparagus is still consumed worldwide as a therapeutic food for its antifungal, anti-inflammatory, and diuretic properties.13

Modern Research

Due to the many nutrients and bioactive compounds found in asparagus, researchers are investigating the possible applications of the plant. While the majority of research has been in vitro, using extracts from the asparagus stalk, there are several promising preliminary animal studies using whole asparagus as the intervention.

Asparagus has a long history of traditional use for the management of diabetes. In one animal study, researchers compared the effectiveness of a methanolic extract of asparagus to that of glibenclamide, a common prescription medication for type 2 diabetes.14 The asparagus extract, when provided at 500 mg/kg daily for 28 days, was shown to be comparable to glibenclamide in improving beta-cell function and insulin secretion. While the actual effects of consuming the whole plant (asparagus) were not considered, the outcomes of this study may suggest a more natural treatment option.

Hypertension (high blood pressure) is a growing problem in the US. High blood pressure can lead to renal (kidney) and cardiovascular disease. To help reduce the risk of hypertension, angiotensin-converting enzyme (ACE) inhibitors are often prescribed to help dilate blood vessels. Asparagus contains naturally-occurring ACE inhibitors.15 When hypertensive rats were fed a diet of freeze-dried, chopped green asparagus, ACE activity was significantly lower than in rats fed a normal diet. The asparagus accounted for 5% of the normal diet. This was the only in vivo study in which asparagus was consumed as a whole food. Further research is necessary to compare effects of consuming the whole food to the effects of using asparagus extracts.

A 2014 literature review summarizes the effects of asparagus extract on the cardiovascular, urinary, and immune systems.6 Instead of using only the stalk of the asparagus plant, this review examines extracts composed of all parts of the asparagus plant, including the roots. This type of asparagus extract reduced homocysteine, an amino acid that promotes thickening and hardening of the arteries and increases the risk of atherosclerosis. Increased amounts of B vitamins and folate have been shown to decrease homocysteine levels, and because of the high levels of these nutrients in the whole-asparagus extract, individuals experienced a 28% reduction in homocysteine levels after four months of use.

Asparagus extract appears to support kidney health via diuretic properties, increasing urinary output and lowering water retention. According to the same 2014 review, the use of asparagus extract normalized kidney function (lowering levels of creatinine and urine protein, and lowering creatinine clearance) and decreased the risk of kidney stones by helping flush out the system before formation occurs.6

Finally, asparagus extract helped maintain and enhance immune function for immunocompromised individuals.6 Radiation and chemotherapy patients took asparagus extract in conjunction with their existing therapy regimens. Individuals who supplemented with asparagus extract had higher immune responses and increased rates of survival and quality of life compared to the control group. Cancer patients who supplemented with asparagus extract extended their lives at least two months during stage 3 and at least six months during stage 2. Further research is necessary to evaluate the effectiveness of using asparagus extract compared to the effectiveness of using the whole plant as complementary cancer treatments.

In addition to the possibility of alleviating the symptoms associated with many chronic diseases, asparagus extract has been evaluated in vitro for its potential to alleviate alcohol-induced hangovers.13 Using all parts of the asparagus plant, a preparation was made to induce cellular metabolism of ethanol. While the constituents of the asparagus stalk alone were effective in increasing ethanol metabolism within the cells, the effect increased when the constituents from the asparagus leaves were added, demonstrating whole-plant synergy. This research highlights the potential hepatoprotective benefits of the asparagus leaf, which is often discarded.

Researchers evaluated six common cooking methods (baking, broiling, pan frying, microwaving, grilling, and steaming) to determine which method of asparagus preparation was the most effective for retaining the important antioxidants glutathione and rutin.16 Glutathione concentrations significantly increased (compared to the raw asparagus control) with short cooking times after baking, microwaving, and steaming. However, decreased glutathione concentrations were seen after baking (18 minutes), frying (14 minutes) or grilling (three minutes) compared to controls. Boiling was the only cooking method that had a negative effect on rutin concentrations: rutin levels decreased after seven minutes of boiling.

Antioxidant activity was measured by three assays: total phenolic content (TPC), ferric reducing/antioxidant power (FRAP), and oxygen radical antioxidant capacity (ORAC).16 Boiling for at least 11 minutes and extended periods of baking caused significant decreases in TPC activity. Steaming, frying, and baking for seven minutes significantly increased the TPC in the asparagus, while other cooking methods had no effect. For FRAP and ORAC measurements, duration of cooking time did not significantly affect the results. However, steaming, frying, baking, and microwaving significantly increased FRAP activity, while baking and frying significantly increased ORAC measurements. All other methods had no effect on antioxidant capabilities. This study suggests that the beneficial properties of asparagus are not significantly affected when cooked in short durations regardless of cooking method.

Few adverse reactions have been reported after asparagus consumption. Because asparagus contains small amounts of oxalates, individuals with a history of oxalate-containing kidney stones should avoid consuming large amounts of asparagus.2 Additionally, asparagus contains purines that can lead to increased discomfort in individuals with gout. Asparagus also induces a unique side effect: a distinctive smell in the consumer’s urine, first recorded in the 18th century by John Arbuthnot, physician to Britain’s Queen Anne.11 Interestingly, some individuals lack either the ability to produce the smell or detect the smell, likely due to a single nucleotide polymorphism.17 For the majority of people, however, asparagus is a safe and delicious addition to a healthy diet.

Nutrient Profile18

Macronutrient Profile: (Per 1 cup [approx. 134 g] raw asparagus)

27 calories

3 g protein

5.2 g carbohydrate

0.2 g fat

Secondary Metabolites: (Per 1 cup [approx. 134 g] raw asparagus)

Excellent source of:

Vitamin K: 55.7 mcg (69.63% DV)

Vitamin A: 1013 IU (20.26% DV)

Very good source of:

Folate: 70 mcg (17.5% DV)

Iron: 2.87 mg (16% DV)

Manganese: 0.28 mg (14% DV)

Thiamin: 0.19 mg (12.67% DV)

Vitamin C: 7.5 mg (12.5% DV)

Dietary Fiber: 2.8 g (11.2% DV)

Riboflavin: 0.19 mg (11.18% DV)

Good source of:

Potassium: 271 mg (7.74% DV)

Vitamin E: 1.51 mg (7.5% DV)

Phosphorus: 70 mg (7% DV)

Niacin: 1.31 mg (6.55% DV)

Vitamin B6: 0.12 mg (6% DV)

Also provides:

Magnesium: 19 mg (4.75% DV)

Calcium: 32 mg (3.2% DV)

DV = Daily Value as established by the US Food and Drug Administration, based on a 2,000 calorie diet.

Recipe: Asparagus, Edamame, and Parsley Salad

Adapted from Better Homes and Gardens19

Ingredients:

4 tablespoons avocado or olive oil, divided

2 tablespoons mirin (sweet rice wine)

1 tablespoon rice vinegar

1 tablespoon reduced-sodium soy sauce or tamari

1 teaspoon salt

1 clove garlic, minced

1 pound fresh asparagus spears, woody ends trimmed off

6 cups of lettuce, washed and torn

1 cup frozen, shelled edamame, thawed

1 cup parsley, coarsely chopped

Directions:

For dressing, combine 1 tablespoon of oil with the mirin, rice vinegar, soy sauce, salt, and garlic in a small bowl. Set aside.

In a large skillet, heat remaining oil over medium-high heat until shimmering. Add asparagus and cook for 3-4 minutes, turning occasionally, until lightly browned and crisp-tender.

Transfer asparagus to a large bowl. Add lettuce, edamame, and parsley. Drizzle in dressing to taste and toss gently.

—Hannah Bauman

References

1. Van Wyk B. Food Plants of the World: An Illustrated Guide. Portland, OR: Timber Press; 2005.

2. Murray M, Pizzorno J, Pizzorno L. The Encyclopedia of Healing Foods. New York, NY: Atria Books; 2005.

3. Blumenthal M, Goldberg A, Brinkmann J, eds. Herbal Medicine: Expanded Commission E Monographs. Austin, TX: American Botanical Council; Newton, MA: Integrative Medicine Communications; 2000.

4. Naeve L. Asparagus. Agriculture Marketing Resource Center website. August 2015. Available here. Accessed January 25, 2016.

5. Onstad D. Whole Foods Companion: A Guide for Adventurous Cooks, Curious Shoppers, and Lovers of Natural Foods. White River Junction, VT: Chelsea Green Publishing; 2004.

6. Chi TT. Asparagus extract for heart, kidney and immune functions. Nutritional Perspectives: Journal of the Council on Nutrition. 2014;37(3):27.

7. Dröge W, Breitkreutz R. Glutathione and immune function. Proc Nutr Soc. 2000;59(4):595-600.

8. Smith R, Harbott E. Asparagus officinalis (garden asparagus). Kew Royal Botanic Gardens website. Available here. Accessed January 21, 2016.

9. Negi JS, Singh P, Joshi GP, Rawat MS, and Bisht VK. Chemical constituents of Asparagus. Pharmacogn Rev. 2010;4(8):215–220.

10. Saponins. Cornell University College of Agriculture and Life Sciences website. September 9, 2015. Available here. Accessed January 25, 2016.

11. National Geographic Society Staff. Edible: An Illustrated Guide to the World’s Food Plants. Des Moines, IA: National Geographic Society; 2008.

12. Yoest H. Plants with Benefits. Pittsburgh, PA: St. Lynn’s Press; 2014.

13. Kim B, Cui Z, Lee S, et al. Effects of Asparagus officinalis extracts on liver cell toxicity and ethanol metabolism. J Food Sci. 2009;74(7):H204-H208.

14. Hafizur RM, Kabir N, Chishti S. Asparagus officinalis extract controls blood glucose by improving insulin secretion and ß-cell function in streptozotocin-induced type 2 diabetic rats. Br J Nutr. 2012;108(9):1586-1595.

15. Sanae M, Yasuo A. Green asparagus (Asparagus officinalis) prevented hypertension by an inhibitory effect on angiotensin-converting enzyme activity in the kidney of spontaneously hypertensive rats. J Agric Food Chem. 2013;61(23):5520-5525.

16. Drinkwater JM, Tsao R, Liu R, Defelice C, Wolyn DJ. Effects of cooking on rutin and glutathione concentrations and antioxidant activity of green asparagus (Asparagus officinalis) spears. Journal of Functional Foods. 2015;12:342-353.

17. Pelchat ML, Bykowski C, Duke FF, Reed DR. Excretion and perception of a characteristic odor in urine after asparagus ingestion: A psychophysical and genetic study. Chem Senses. 2011;36(1):9-17.

18. Basic Report: 11011, Asparagus, raw. Agricultural Research Service, United States Department of Agriculture website. Available here. Accessed January 20, 2016.

19. Asparagus, Edamame, and Parsley Salad. Better Homes and Gardens website. Available here. Accessed January 22, 2016.