GRAPEFRUIT

The grapefruit is a subtropical citrus tree grown for its bitter fruit which was originally named the "forbidden fruit" of Barbados.^[1]

These evergreen trees are usually found at around 5-6 m (16-19 feet) tall, although they can reach 13-15 m (43-49 feet). The leaves are dark green, long (up to 150 mm, or 6 inches) and thin. It produces 5 cm (2-inch) white four-petaled flowers. The fruit is yellow-orange skinned, largely oblate and 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.^[2]

The fruit has only become popular from the late 19th century; before that it was only grown as an ornamental plant. The US quickly became a major producer of the fruit, with orchards in Florida, Texas, Arizona, and California. In Spanish, the fruit is known as toronja or pomelo.

History

The fruit was first documented in 1750 by the Rev. Griffith Hughes describing specimens from Barbados.^[3] Currently, the grapefruit is said to be one of the "Seven Wonders of Barbados."^[4] It had developed as a hybrid of the pomelo (Citrus maxima) with the sweet orange (Citrus sinensis), though it is closer to the former.^[5] It was brought to Florida by Count Odette Philippe in 1823 in what is now known as Safety Harbor. Further crosses have produced the tangelo (1905), the minneola (1931), and the sweetie (1984). The sweetie has very small genetic and other differences from pomelo.

The grapefruit was known as the shaddock or shattuck until the 1800s, taking the name from Captain Shaddock, who introduced the pomelo to the Caribbean from Polynesia in the 17th 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.^[6][7]

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 Ruby Red the grapefruit transformed into a real agricultural fruit. The Red grapefruit, starting from the Ruby Red, has even become a symbol 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,^[8] with Rio Red is the current (2007) Texas grapefruit with registered trademarks Rio Star and Ruby-Sweet, also sometimes promoted as "Reddest" and "Texas Choice". The grapefruit was also used in indian villages.

Drug interactions

Main article: List of drugs affected by grapefruit

Grapefruit can have a number of interactions with drugs, often increasing the effective potency of compounds. Grapefruit contains naringin, bergamottin and dihydroxybergamottin, which inhibit the protein isoform CYP3A4 predominately in the liver. It is via inhibition of this enzyme that grapefruit increases the effects of a variety of drugs.^{[9][10][11][12][13]} The effect of grapefruit juice with regard to drug absorption was originally discovered in 1989. However, the effect became well-publicized after being responsible for a number of deaths due to overdosing on medication.^[14]

Grapefruit juice may be the first 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.^[15]

Nutritional properties

Grapefruit, raw, white, all areas Nutritional value per 100 g (3.5 oz)
Energy 30 kcal 140 kJ
Carbohydrates 8.41 g - Sugars 7.31 g - Dietary fiber 1.1 g Fat 0.10 g Protein 0.69 g Water 90.48 g Thiamin (Vit. B1) 0.037 mg 3% Riboflavin (Vit. B2) 0.020 mg 1% 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% Vitamin C 33.3 mg 56% Calcium 12 mg 1% Iron 0.06 mg 0% Magnesium 9 mg 2% Phosphorus 8 mg 1% Potassium 148 mg 3% Zinc 0.07 mg 1% Manganese 0.013 mg
Percentages are relative to US recommendations for adults. Source: USDA Nutrient database

Grapefruit is an excellent source of many nutrients and phytochemicals, able to contribute to a healthy diet. Grapefruit is a good source of vitamin C,^[16][17] pectin fiber,^[18] and the pink and red hues contain the beneficial antioxidant lycopene.^[16][19] Studies have shown grapefruit helps lower cholesterol^[16][20] and there is evidence that the seeds have high levels of antioxidant properties.^[21] 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.^[22]

Grapefruit seed extract has been claimed to have strong antimicrobial propoerties, with proven activity against bacteria and fungi. However, no studies have demonstrated any efficacy by grapefruit seed extract as an antimicrobial for either bacteria or fungi. 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.^{[23][24][25][26][27]}

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.^[28] Howewer, there is a study showing that grapefruit consumption may not increase breast cancer risk. Furthermore, related studies showed a significant decrease in breast cancer risk with greater intake of grapefruit in women who never used hormone therapy.^[29]

Grapefruit sweets

In Costa Rica, especially in Atenas, grapefruits are cooked in a way that removes their sourness, and renders them as sweets; they are also stuffed with dulce de leche, resulting in a dessert called toronja rellena (stuffed grapefruit).

Other uses

Grapefruit peel oil is used in aromatherapy for its fat-disgregating properties helping against cellulitis and it is historically known for its aroma.^[30] Its high vitamin C content also promotes the synthesis of new collagen, helping improve skin tone. It also improves blood circulation and stimulates the lymphatic system to drain toxins from the body.

Grapefruit has also been investigated in cancer medicine pharmacodynamics. Although it inhibits the metabolism of some drugs, which is generally considered a bad thing, this allows some cancer drugs to be used at a lower dose, because of inhibited metabolism. This requires a smaller amount, which, in principle, can reduce the overall cost of an "effective" dose.^[31]