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Grapefruit, hybrid citrus.
Scientific classification
Species:C. × paradisi
Binomial name
Citrus × paradisi
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Grapefruit, hybrid citrus.
Scientific classification
Species:C. × paradisi
Binomial name
Citrus × paradisi

The grapefruit (Citrus × paradisi) is a subtropical citrus tree known for its bitter fruit, an 18th-century hybrid first bred in Barbados.[1] When found, it was named the "forbidden fruit";[2] and it has also been misidentified with the pomelo or shaddock (C. maxima), one of the parents of this hybrid, the other being sweet orange (C. × sinensis).

These evergreen trees usually grow to around 5–6 meters (16–20 ft) tall, although they can reach 13–15 meters (43–49 ft). The leaves are dark green, long (up to 150 mm, 6 inches) and thin. It produces 5 cm (2 in) white four-petaled flowers. The fruit is yellow-orange skinned and largely an oblate spheroid; it ranges in diameter from 10–15 cm. The flesh is segmented and acidic, varying in color depending on the cultivars, which include white, pink and red pulps of varying sweetness. The 1929 US Ruby Red (of the Redblush variety) has the first grapefruit patent.[3]

The fruit has become popular since the late 19th century; before that it was only grown as an ornamental plant. The United States quickly became a major producer of the fruit, with groves in Florida, Texas, Arizona, and California. In Spanish, the fruit is known as toronja[4] or pomelo.[5]



1750 Engraving of The Forbidden Fruit Tree by Georg Dionysius Ehret

One ancestor of the grapefruit was the Jamaican sweet orange (Citrus sinensis), itself an ancient hybrid of Asian origin; the other was the Indonesian pomelo (C. maxima). One story of the fruit's origins is that a certain "Captain Shaddock"[6] brought pomelo seeds to Jamaica and bred the first fruit.[7] However, it probably originated as a naturally-occurring hybrid.[1]

The Trunk, Leaves, and Flowers of this Tree, very much resemble
those of the Orange-tree.
The Fruit, when ripe, is something longer and larger than the largest
Orange; and exceeds, in the Delicacy of its Taste, the Fruit of every
Tree in this or any of our neighbouring Islands.
It hath somewhat of the Taste of a Shaddock; but far exceeds that, as
well as the best Orange, in its delicious Taste and Flavour.

—Description from Hughes' 1750 Natural History of Barbados.

The hybrid fruit, then called "the forbidden fruit", was first documented in 1750 by a Welshman, Rev. Griffith Hughes, who described specimens from Barbados in The Natural History of Barbados.[8][9] Currently, the grapefruit is said to be one of the "Seven Wonders of Barbados."[10]

The grapefruit was brought to Florida by Count Odet Philippe in 1823 in what is now known as Safety Harbor. Further crosses have produced the tangelo (1905), the Minneola tangelo (1931), and the oroblanco (1984).

The grapefruit was known as the shaddock or shattuck until the 19th century. Its current name alludes to clusters of the fruit on the tree, which often appear similar to grapes.[11] Botanically, it was not distinguished from the pomelo until the 1830s, when it was given the name Citrus paradisi. Its true origins were not determined until the 1940s. This led to the official name being altered to Citrus × paradisi, the "×" identifying its hybrid origin.[12][13]

Kimball Chase Atwood

An early pioneer in the American citrus industry was Kimball Chase Atwood, a wealthy entrepreneur who founded the Atwood Grapefruit Co. in the late 19th century. The Atwood Grove became the largest grapefruit grove in the world, with an annual production of 80,000 boxes of fruit.[14] It was there that pink grapefruit was first discovered in 1906.[15]

Ruby Red grapefruit

The 1929 Ruby Red patent was associated with real commercial success, which came after the discovery of a red grapefruit growing on a pink variety. Only with the introduction of the Ruby Red did the grapefruit transform into a real agricultural success. The Red grapefruit, starting with the Ruby Red, has even become a symbolic fruit of Texas, where white "inferior" grapefruit were eliminated and only red grapefruit were grown for decades. Using radiation to trigger mutations, new varieties were developed to retain the red tones which typically faded to pink,[16] the Rio Red variety is the current (2007) Texas grapefruit with registered trademarks Rio Star and Ruby-Sweet, also sometimes promoted as "Reddest" and "Texas Choice".


The Florida Department of Citrus states "the primary varieties of Florida grapefruit are Ruby Red, Pink, Thompson, Marsh and Duncan. The fresh grapefruit season typically runs from October through June."[17]


Grapefruit and pomelo output in 2005

The United States is the top producer of grapefruit and pomelo followed by China and South Africa.

Top ten grapefruit (inc. pomelos) Producers — 2007
CountryProduction (Tonnes)Footnote
 United States1580000
 People's Republic of China547000F
 South Africa430000F
No symbol = official figure, P = official figure, F = FAO estimate, * = Unofficial/Semi-official/mirror data, C = Calculated figure A = Aggregate (may include official, semi-official or estimates);

Source: Food And Agricultural Organization of United Nations: Economic And Social Department: The Statistical Division

Colors and flavors

A grapefruit from southern California

Grapefruit comes in many varieties, determinable by color, which is caused by the pigmentation of the fruit in respect of both its state of ripeness.[18] The most popular varieties cultivated today are red, white, and pink hues, referring to the internal pulp color of the fruit. The family of flavors range from highly acidic and somewhat sour to sweet and tart.[18] Grapefruit mercaptan, a sulfur-containing terpene, is one of the substances which has a strong influence on the taste and odor of grapefruit, compared with other citrus fruits.[19]

Drug interactions

Grapefruit mercaptan

Grapefruit can have a number of interactions with drugs,[20] often increasing the effective potency of compounds. Grapefruit contains a number of polyphenolic compounds, including the flavanone naringin, alongside the two furanocoumarins bergamottin and dihydroxybergamottin. These inhibit the drug-metabolizing enzyme isoform CYP3A4 predominately in the small intestine, but at higher doses also inhibit hepatic CYP3A4.[21] It is via inhibition of this enzyme that grapefruit increases the effects of a variety of drugs by increasing their bioavailability.[22][23][24][25][26][27] In particular grapefruit and bitter oranges are known to interact with statins. Because of this unique property, grapefruit has a very bitter taste when mixed with milk or similar dairy products.

Grapefruit juice may be the first drug-interacting fruit juice documented, but apple and orange juices have been also implicated in interfering with etoposide, a chemotherapy drug, some beta blocker drugs used to treat high blood pressure, and cyclosporine, taken by transplant patients to prevent rejection of their new organs.[28] Some citrus-based carbonated beverages (e.g., "Sun Drop") also contain enough grapefruit juice to cause drug interactions, particularly in patients taking cyclosporine.

Unlike other fruits, grapefruit contains a large amount of naringin, and it can take up to 72 hours before the effects of the naringin on the CYP3A4 enzyme are seen. This is particularly problematic due to the fact that only 4 oz of grapefruit contain enough naringin to inhibit the metabolism of substrates of CYP3A4.

Nutritional properties

Grapefruit, raw, white, all areas
Nutritional value per 100 g (3.5 oz)
Energy138 kJ (33 kcal)
Carbohydrates8.41 g
- Sugars7.31 g
- Dietary fiber1.1 g
Fat0.10 g
Protein0.69 g
Water90.48 g
Thiamine (vit. B1)0.037 mg (3%)
Riboflavin (vit. B2)0.020 mg (2%)
Niacin (vit. B3)0.269 mg (2%)
Pantothenic acid (B5)0.283 mg (6%)
Vitamin B60.043 mg (3%)
Folate (vit. B9)10 μg (3%)
Vitamin C33.3 mg (40%)
Calcium12 mg (1%)
Iron0.06 mg (0%)
Magnesium9 mg (3%)
Phosphorus8 mg (1%)
Potassium148 mg (3%)
Zinc0.07 mg (1%)
Manganese0.013 mg
Percentages are relative to
US recommendations for adults.
Source: USDA Nutrient Database

Grapefruit is an excellent source of many nutrients and phytochemicals that contribute to a healthy diet. Grapefruit is a good source of vitamin C,[18][29] contains the fiber pectin,[30] and the pink and red hues contain the beneficial antioxidant lycopene.[18][31] Studies have shown grapefruit helps lower cholesterol,[18][32] and there is evidence that the seeds have antioxidant properties.[33] Grapefruit forms a core part of the "grapefruit diet", the theory being that the fruit's low glycemic index is able to help the body's metabolism burn fat.[34]

Grapefruit seed extract (GSE) has been shown to have strong antimicrobial properties against fungi.[35] It is also believed to have antimicrobial properties for bacteria, however there are no known studies that demonstrate its efficacy. Additionally, although GSE is promoted as a highly effective plant-based preservative by some natural personal care manufacturers, studies have shown that the apparent antimicrobial activity associated with GSE preparations is merely due to contamination with synthetic preservatives.[36][37][38][39][40]

Since grapefruit juice is known to inhibit enzymes necessary for the clearance of some drugs and hormones, some have hypothesized that grapefruit juice may play an indirect role in the development of hormone-dependent cancers. A 2007 study found a correlation between eating a quarter of grapefruit daily and a 30% increase in risk for breast cancer in post-menopausal women. The study points to the inhibition of CYP3A4 enzyme by grapefruit, which metabolizes estrogen.[41] However, a 2008 study has shown that grapefruit consumption does not increase breast cancer risk and found a significant decrease in breast cancer risk with greater intake of grapefruit in women who never used hormone therapy.[42]

Grapefruit contains large quantities of a simple polyamine called spermidine, which may be related to aging. It is known to be necessary for cell growth and maturation, and as cells age their level of spermidine is known to fall. Scientists have shown that feeding spermidine to worms, fruit flies and yeast significantly prolongs their lifespan. In addition, adding spermidine to the diet of mice decreased molecular markers of aging, and when human immune cells were cultured in a medium containing spermidine, they also lived longer.[43]

Nutritional information

100g of grapefruit contains the following nutritional information according to the USDA:[44]

Grapefruit sweets

In Costa Rica, especially in Atenas, grapefruit are often cooked to remove their sourness, rendering them as sweets; they are also stuffed with dulce de leche, resulting in a dessert called toronja rellena (stuffed grapefruit).

Other uses

Grapefruit has also been investigated in cancer medicine pharmacodynamics. Its inhibiting effect on the metabolism of some drugs may allow smaller doses to be used, which can help to reduce costs.[45]

See also


  1. ^ a b Carrington, Sean; Fraser, HenryC (2003). "Grapefruit". A~Z of Barbados Heritage. Macmillan Caribbean. pp. 90–91. ISBN 0-333-92068-6. "One of many citrus species grown in Barbados. This fruit is believed to have originated in Barbados as a natural cross between sweet orange (C. sinesis) and Shadock (C. grandis), both of which were introduced from Asia in the seventeenth century. The grapefruit first appeared as an illustration entitled 'The Forbidden Fruit Tree' in the Rev. Griffith Hughes' The Natural History of Barbados (1750). This accords with the scientific name which literally means 'citrus of paradise'. The fruit was obviously fairly common around that time since George Washington in his Barbados Journal (1750-1751) mentions 'the Forbidden Fruit' as one of the local fruit available at a dinner party he attended. The plant was later described in the 1837 Flora of Jamaica as the Barbados Grapefruit. These historical arguments and experimental work on leaf enzymes and oils from possible parents all support a Barbadian origin for the fruit." 
  2. ^ Dowling, Curtis F.; Morton, Julia Frances (1987). Fruits of warm climates. Miami, FL: J. F. Morton. ISBN 0-9610184-1-0. OCLC 16947184. 
  3. ^ Texas grapefruit history, TexaSweet. Retrieved 2 July 2008.
  4. ^ "Google translation of Spanish ''toronja''". Retrieved 2011-12-17. 
  5. ^ "Google translation of Spanish ''pomelo''". Retrieved 2011-12-17. 
  6. ^ A possible identification with an actual Captain Chaddock who traded in the West Indies in the 17th century, was suggested by J. Kumamoto, R. W. Scora, H. W. Lawton and W. A. Clerx, "Mystery of the forbidden fruit: Historical epilogue on the origin of the grapefruit, Citrus paradisi (Rutaceae)", Economic Botany, 41.1 (January, 1987:97-107).
  7. ^ Grapefruit: a fruit with a bit of a complex in Art Culinaire (Winter, 2007)
  8. ^ World Wide Words: Questions & Answers; Grapefruit. Abstract
  9. ^ "Welchman Hall Gully, Barbados" Barbados National Trust 2010 Retrieved 11 July 2010 "The Development of the Gully - The Gully was once part of a plantation owned by a Welshman called General William Asygell Williams over 200 years ago. Hence the name "Welchman Hall" gully. It was this man who first developed the gully with exotic trees and an orchard. Interestingly, the grapefruit is originally from Barbados and is rumoured to have started in Welchman Hall Gully." 
  10. ^ Barbados Seven Wonders: The Grapefruit Tree. Abstract
  11. ^ "How did the grapefruit get its name?" Library of Congress. Science Reference Service, Everyday Mysteries. Retrieved August 2, 2009.
  12. ^ Texas Citrus: Puzzling Beginnings. Article
  13. ^ University of Florida: IFAS Extension; The Grapefruit. Fact Sheet PDF
  14. ^ "Manatee County a big part of citrus history". 2004-08-16. Retrieved 2011-12-17. 
  15. ^ "Article". Retrieved 2011-12-17. 
  16. ^ William J Broad (28 August 2007). "Useful Mutants, Bred With Radiation". New York Times. 
  17. ^ "Go Florida Grapefruit". Go Florida Grapefruit. Retrieved 2011-12-17. 
  18. ^ a b c d e The World's Healthiest Foods; Grapefruit. The George Mateljan Foundation. Article
  19. ^ A. Buettner, P. Schieberle (1999). "Characterization of the Most Odor-Active Volatiles in Fresh, Hand-Squeezed Juice of Grapefruit (Citrus paradisi Macfayden)". J. Agric. Food Chem. 47 (12): 5189–5193. doi:10.1021/jf990071l. PMID 10606593. 
  20. ^ Seden K. Dickinson L. Khoo S. Back D.. Grapefruit-drug interactions. [Review]. Drugs. 2010;70(18):2373-407. PMID 21142260.
  21. ^ Veronese ML, Gillen LP, Burke JP, Dorval EP, Hauck WW, Pequignot E, Waldman SA, Greenberg HE. Exposure-dependent inhibition of intestinal and hepatic CYP3A4 in vivo by grapefruit juice. Journal of Clinical Pharmacology. 2003;43(8):831–9. doi:10.1177/0091270003256059. PMID 12953340.
  22. ^ He K, Iyer KR, Hayes RN, Sinz MW, Woolf TF, Hollenberg PF (1998). "Inactivation of cytochrome P450 3A4 by bergamottin, a component of grapefruit juice". Chem. Res. Toxicol. 11 (4): 252–9. doi:10.1021/tx970192k. PMID 9548795. 
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  24. ^ Garg SK, Kumar N, Bhargava VK, Prabhakar SK (1998). "Effect of grapefruit juice on carbamazepine bioavailability in patients with epilepsy". Clin. Pharmacol. Ther. 64 (3): 286–8. doi:10.1016/S0009-9236(98)90177-1. PMID 9757152. 
  25. ^ Bailey DG, Dresser GK (2004). "Interactions between grapefruit juice and cardiovascular drugs". Am J Cardiovasc Drugs 4 (5): 281–97. doi:10.2165/00129784-200404050-00002. PMID 15449971. 
  26. ^ Bressler R (2006). "Grapefruit juice and drug interactions. Exploring mechanisms of this interaction and potential toxicity for certain drugs". Geriatrics 61 (11): 12–8. PMID 17112309. 
  27. ^ Bakalar, Nicholas (21 March 2006). "Experts Reveal the Secret Powers of Grapefruit Juice". New York Times. 
  28. ^ "Fruit juice 'could affect drugs'". BBC News. 20 August 2008.  :]
  29. ^ Fellers PJ, Nikdel S, Lee HS (August 1990). "Nutrient content and nutrition labeling of several processed Florida citrus juice products". J Am Diet Assoc 90 (8): 1079–84. PMID 2380455. 
  30. ^ Cerda JJ, Robbins FL, Burgin CW, Baumgartner TG, Rice RW (September 1988). "The effects of grapefruit pectin on patients at risk for coronary heart disease without altering diet or lifestyle". Clin Cardiol 11 (9): 589–94. doi:10.1002/clc.4960110902. PMID 3229016. 
  31. ^ Lee HS (May 2000). "Objective measurement of red grapefruit juice color". J. Agric. Food Chem. 48 (5): 1507–11. doi:10.1021/jf9907236. PMID 10820051. 
  32. ^ Platt R (2000). "Current concepts in optimum nutrition for cardiovascular disease". Prev Cardiol 3 (2): 83–7. doi:10.1111/j.1520-037X.2000.80364.x. PMID 11834923. 
  33. ^ Armando C, Maythe S, Beatriz NP (1997). "Antioxidant activity of grapefruit seed extract on vegetable oils". J Sci Food Agric. 77 (4): 463–7. doi:10.1002/(SICI)1097-0010(199808)77:4<463::AID-JSFA62>3.0.CO;2-1. 
  34. ^ WMUR Ch. 9: New Hampshire news, weather, sports and entertainment. Researchers Put Grapefruit Diet To Test: Grapefruit Compound Lowers Cholesterol, Helps Regulate Insulin. June 11, 2003. Article
  35. ^ Ignacio, C. and Thai, D. (2005). "Comparative Analysis of Antifungal Activity of Natural Remedies Versus Miconazole Nitrate Salt Against Candida Albicans"
  36. ^ Sakamoto S, Sato K, Maitani T, Yamada T (1996). "[Analysis of components in natural food additive "grapefruit seed extract" by HPLC and LC/MS]" (in Japanese). Eisei Shikenjo Hokoku (114): 38–42. PMID 9037863. 
  37. ^ von Woedtke T, Schlüter B, Pflegel P, Lindequist U, Jülich WD (June 1999). "Aspects of the antimicrobial efficacy of grapefruit seed extract and its relation to preservative substances contained". Pharmazie 54 (6): 452–6. PMID 10399191. 
  38. ^ Takeoka G, Dao L, Wong RY, Lundin R, Mahoney N (July 2001). "Identification of benzethonium chloride in commercial grapefruit seed extracts". J. Agric. Food Chem. 49 (7): 3316–20. doi:10.1021/jf010222w. PMID 11453769. 
  39. ^ Takeoka GR, Dao LT, Wong RY, Harden LA (September 2005). "Identification of benzalkonium chloride in commercial grapefruit seed extracts". J. Agric. Food Chem. 53 (19): 7630–6. doi:10.1021/jf0514064. PMID 16159196. 
  40. ^ Ganzera M, Aberham A, Stuppner H (May 2006). "Development and validation of an HPLC/UV/MS method for simultaneous determination of 18 preservatives in grapefruit seed extract". J. Agric. Food Chem. 54 (11): 3768–72. doi:10.1021/jf060543d. PMID 16719494. 
  41. ^ Monroe KR, Murphy SP, Kolonel LN, Pike MC (August 2007). "Prospective study of grapefruit intake and risk of breast cancer in postmenopausal women: the Multiethnic Cohort Study". Br. J. Cancer 97 (3): 440–5. doi:10.1038/sj.bjc.6603880. PMC 2360312. PMID 17622247. // 
  42. ^ Kim EH, Hankinson SE, Eliassen AH, Willett WC (January 2008). "A prospective study of grapefruit and grapefruit juice intake and breast cancer risk" (PDF). Br. J. Cancer 98 (1): 240–1. doi:10.1038/sj.bjc.6604105. PMC 2359690. PMID 18026192. Retrieved 26 June 2009. 
  43. ^ "". 
  44. ^ "Search the USDA National Nutrient Database for Standard Reference". Retrieved 2011-12-17. 
  45. ^ Gandey A (18 July 2007). "Cut Cancer Drug Costs By Exploring Food Interactions". Medscape Medical News. 

"Why Texas Grapefruit Is Important for Your Health", source: Pittman Davis, 2009

External links