|Grapefruit, hybrid citrus.|
|Species:||C. × paradisi|
|Citrus × paradisi
The grapefruit (Citrus × paradisi) is a subtropical citrus tree known for its sour to semi-sweet fruit, an 18th-century hybrid first bred in Barbados. When found, it was named the "forbidden fruit"; 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).
The evergreen grapefruit 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 glossy dark green, long (up to 15 centimeters (5.9 in)) and thin. It produces 5 cm (2 in) white four-petaled flowers. The fruit is yellow-orange skinned and generally an oblate spheroid in shape; it ranges in diameter from 10–15 centimeters (3.9–5.9 in). The flesh is segmented and acidic, varying in color depending on the cultivars, which include white, pink and red pulps of varying sweetness (generally, the redder varieties are sweeter). The 1929 US Ruby Red (of the Redblush variety) has the first grapefruit patent.
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" brought pomelo seeds to Jamaica and bred the first fruit. However, it probably originated as a naturally occurring hybrid.
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. Currently, the grapefruit is said to be one of the "Seven Wonders of Barbados."
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. 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.
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 a yearly output of 80,000 boxes of fruit. It was there that pink grapefruit was first discovered in 1906.
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. 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, 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 Rio Red is a mutation bred variety which was developed by treatment of bud sticks with thermal neutrons. Its improved attributes of mutant variety are fruit and juice color, deeper red, and wide adaptation. 
The Star Ruby is the darkest of the red varieties. Developed from an irradiated Hudson grapefruit, it has found limited commercial success because it is more difficult to grow than other varieties.
The primary varieties of Texas and Florida grapefruit are Ruby Red, Pink, Thompson, Marsh and Duncan.
|Top ten grapefruit (inc. pomelos) producers — 2007|
|Country||Production (metric tons)||Footnote|
|People's Republic of China||547,000||F|
|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);
Colors and flavors
Grapefruit comes in many varieties, determinable by color, which is caused by the pigmentation of the fruit in respect of its state of ripeness. 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. 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.
Grapefruit can have a number of interactions with drugs, often increasing the effective potency of compounds. Researchers have identified 85 drugs with which grapefruit is known to have an adverse reaction. 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 predominantly in the small intestine, but at higher doses also inhibit hepatic CYP3A4. It is via inhibition of this enzyme that grapefruit increases the effects of a variety of drugs by increasing their bioavailability. In particular grapefruit and bitter oranges are known to interact with statins.
When drugs are taken orally, they enter the gut lumen to be absorbed in the small intestine and sometimes, in the stomach. In order for drugs to be absorbed, they must pass through the epithelial cells that line the lumen wall before they can enter the hepatic portal circulation to be distributed systemically in blood circulation. Drugs are metabolized by drug-specific metabolizing enzymes in the epithelial cells. Metabolizing enzymes transform these drugs into metabolites. The primary purpose for drug metabolism is to detoxify, inactivate, solubilize and eliminate these drugs. As a result, the amount of the drug in its original form that reaches systemic circulation is reduced due to this first-pass metabolism.
Grapefruit juice contains furanocoumarins. Furanocoumarins irreversibly inhibit a cytochrome P450 metabolizing enzyme called CYP3A4, as stated above. CYP3A4 is a metabolizing enzyme for almost 50% of drugs, and is found in the liver and small intestinal epithelial cells. As a result, many drugs are impacted by consumption of grapefruit juice. When the metabolizing enzyme is inhibited, less of the drug will be metabolized by it in the epithelial cells. A decrease in drug metabolism means more of the original form of the drug could pass unchanged to systemic blood circulation. An unexpected high dose of the drug in the blood could lead to fatal drug toxicity.
The furanocoumarins found in grapefruit juice are natural chemicals. Thus, they are present in all forms of the fruit, including freshly squeezed juice, frozen concentrate, and whole fruit. All these forms of the grapefruit juice have the potential to limit the metabolizing activity of CYP3A4. One whole grapefruit, or a glass of 200 mL of grapefruit juice can cause drug overdose toxicity.
According to a review done by the Canadian Medical Association, there is an increase in the number of potential drugs that can interact with grapefruit juice. From 2008 to 2012, the percentage of drugs that interact with grapefruit juice and causes serious harmful effects (gastrointestinal bleeding, nephrotoxicity) has increased from 17 to 43 percent.
The interaction between grapefruit juice and other medication depends on the drug, and not the class of the drug. Drugs that interact with grapefruit juice share 3 common features: they are taken orally, normally only a small amount enters systemic blood circulation, and they are metabolized by CYP3A4.
Inhibition of the CPA 3A4 enzyme is irreversible and lasts a significant period of time. It takes around 24 hours to regain 50% of the enzyme activity and it can take 72 hours for the enzyme to completely return to activity. For this reason, simply separating grapefruit consumption and medication taken daily does not avoid the interaction. For medications that interact due to inhibition of OATP (organic anion-transporting polypeptides), a relative short period of time is needed to avoid this interaction. A 4-hour interval between grapefruit consumption and the medication should suffice. For drugs recently sold on the market, drugs have information pages (monographs) that provide information on any potential interaction between a medication and grapefruit juice. Because there is a growing number of medications that are known to interact with grapefruit juice, patients should consult a pharmacist or physician before planning to take grapefruit juice with their medications.
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. 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 value per 100 g (3.5 oz)|
|Energy||138 kJ (33 kcal)|
|- Sugars||7.31 g|
|- Dietary fiber||1.1 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 B6||0.043 mg (3%)|
|Folate (vit. B9)||10 μg (3%)|
|Choline||7.7 mg (2%)|
|Vitamin C||33.3 mg (40%)|
|Vitamin E||0.13 mg (1%)|
|Calcium||12 mg (1%)|
|Iron||0.06 mg (0%)|
|Magnesium||9 mg (3%)|
|Manganese||0.013 mg (1%)|
|Phosphorus||8 mg (1%)|
|Potassium||148 mg (3%)|
|Zinc||0.07 mg (1%)|
|Link to USDA Database entry
Percentages are roughly approximated
using 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, contains the fiber pectin, and the pink and red hues contain the beneficial antioxidant lycopene. Studies have shown grapefruit helps lower cholesterol, and there is evidence that the seeds have antioxidant properties. 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.
Grapefruit seed extract (GSE) has been shown to have strong antimicrobial properties against fungi. 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.
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. 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.
There is a popular myth that grapefruits contain high amounts of spermidine, a simple polyamine that may be related to aging. The myth probably relies on the confusion between spermidine and putrescine. While citrus fruits show high amounts of putrescine, they contain very little spermidine.
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). In Haiti, grapefruit is used primarily for its juice (jus de Chadèque), but is also used to make jam (confiture de Chadèque).
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.
- Grapefruit juice
- Grapefruit knife
- Grapefruit seed extract
- Grapefruit spoon
- Naringenin (not to be confused with naringin)
- 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 Shaddock (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 is '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. The historical arguments and experimental work on leaf enzymes and oils from possible parents all support a Barbadian origin for the fruit."
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"Why Texas Grapefruit Is Important for Your Health", source: Pittman Davis, 2009
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