Source  : Health Canada. Canadian Nutrient File , 2010.

The benefits of grapefruit

• Cancer (prevention) . Several studies have shown that the consumption of citrus fruits, including grapefruit , is linked to the prevention of certain types of cancer ^{3 , 4,22,41,45} , such as cancer of the esophagus, cancer of the stomach, colon, mouth and pharynx cancer . According to one of these studies ⁴⁵ , moderate consumption of citrus fruits (1 to 4 servings per week) would reduce the risk of cancers affecting the digestive tract and the upper respiratory system. With specific regard to pancreatic cancer, however, studies remain controversial . ⁴⁶A population study suggests that the daily consumption of citrus fruits combined with a high consumption of green tea (1 cup and more per day) is associated with a greater decrease in the incidence of cancer ⁴⁴ .

  The consumption of grapefruit could, according to a large prospective (population) study , reduce the risks of breast cancer ⁴⁷ . However, other studies have shown opposite results ⁴⁸ , or an absence of link ⁵⁹ . In addition, researchers have observed that the incidence of lung cancer was lower in people who consumed more white grapefruit ¹⁷ .

• Cancer (slowing progression) . Antioxidant compounds found in citrus fruits (limonoids) have shown anticancer effects in vitro and in animals. They could decrease the proliferation of cancer cells ^{19 , 20,42,43} in the breast ^{14-16 , 22} , in the stomach ²⁰ , in the lung ²⁰ , in the mouth ^{24 , 53} and in the colon ⁴² .
• Blood lipids . In patients with hypercholesterolemia, the consumption of 2 grapefruits per day would have the property of lowering the cholesterol and triglyceride levels in the blood and increasing the antioxidant capacity in the blood ¹³ . Consumption of red grapefruit has more effect on blood lipids (fat) than white grapefruit ⁵¹ . In people suffering from obesity, the consumption of ½ grapefruit (3 times a day) would not influence the lipid profile, but could play a role in weight loss ⁵² .Several animal studies have shown that the flavonoids and limonoids present in citrus juices have the property of lowering blood cholesterol ^{7 , 10,26,49} . They could also increase HDL (“good”) cholesterol ⁹ and reduce blood triglycerides ⁴⁹ and cholesterol oxidation ¹¹ . It should be noted that, still in animals, the consumption of fresh grapefruits would be more advantageous for the lipid profile (blood cholesterol and triglyceride levels) and antioxidant activity than taking a supplement.naringin (a flavonoid of grapefruit) ¹² . In addition, certain flavonoids could improve the elasticity of the wall of blood vessels ⁸ .
• Blood sugar and weight loss . In obese people with metabolic syndrome, consumption of grapefruit (half a fruit a day before each meal for 12 weeks) resulted in significant weight loss compared to a control group (1.6 kg versus 0.3 kg) . It also significantly reduced their insulin resistance ⁵² . In diabetic animals, naringin supplementation (a flavonoid grapefruit) allowed significantly reduce the glucose blood ¹⁸ . This compound could play a role in the prevention of hyperglycemia.

• Inflammation . Several studies have shown that citrus flavonoids have anti-inflammatory properties. They would inhibit the synthesis and activity of mediators involved in inflammation (derivatives of arachidonic acid, prostaglandins E2, F2 and thromboxanes A2) ⁵⁴ .
• Other. Among other effects observed, 2 compounds found in citrus fruits (limonin and nomiline) are said to inhibit replication of the human immunodeficiency virus (HIV), in addition to inhibiting the protease activity of virus ²⁷ . Nomiline and other citrus limonoids are thought to strengthen the immune system in animals ²⁸ . These results are promising, but have not been the subject of controlled clinical studies. It is therefore currently impossible to transpose these effects in humans.

Several prospective and epidemiological studies have shown that high consumption of fruits and vegetables lowers the risk of cardiovascular disease ³⁸ , certain cancers ³⁹ and other chronic diseases ^{1 , 2,40} .

What does grapefruit contain?

Flavonoids
Grapefruit contains different types of flavonoids . These antioxidant compounds help neutralize free radicals in the body and thus prevent the onset of cardiovascular disease, certain cancers and other chronic diseases. The grapefruit contains mainly naringin ⁵ , but also hesperetin in smaller quantities. It is the white part of the fruit peel that contains the most flavonoids, and the concentrations vary greatly depending on the crop.

The absorption and use of naringin and hesperetin in the human body differs from person to person ⁶ . Either way, ingesting 1 cup (250 mL) grapefruit juice provides a high concentration of flavonoids in the blood. Regular consumption of this juice could therefore have beneficial effects on health.

Limonoids
The limonoid found mainly in seed citrus ¹⁹ as well as in juice ²⁰ . Depending on their type, they can be responsible for the bitter flavor of the fruits that contain it or even be tasteless. Limonin is the main limonoid of grapefruit. It would, with other limonoids present in citrus juices, the property of lowering blood cholesterol in animals ^{26 , 43} .

These compounds have a certain antioxidant capacity ²¹ . They could also lead to the apoptosis of cancerous neuroblastic cells (embryonic nerve cells, which then differentiate into neurons) ²³ . Other studies suggest that citrus limonoids may prevent certain types of cancer in animals. For example, obacunone, a type of limonoid, has been shown to decrease the incidence of colon tumors ²⁵ and decrease the number of mouth tumors ¹⁹. However, there is currently no data on a similar effect in humans. The synergistic action of several limonoids between themselves, or with other compounds (such as flavonoids), could accentuate their action on cancer cells.

Carotenoids
Grapefruits contain high amounts of beta carotene. The red and pink fruits also contain lycopene, another compound in the carotenoid family . Grapefruits also contain other carotenoids, but in smaller quantities. Carotenoids have antioxidant properties. Consumption of carotenoid-rich foods is thought to be associated with a lower risk of developing several diseases (for example, cancer and cardiovascular disease, although studies on the subject are controversial ²⁹⁾ .

Soluble fiber
About 2/3 of the grapefruit fiber is said to be soluble fiber, such as pectin . They are mainly found in the bark and in the white membrane around the flesh ( albedo ). By their ability to lower blood cholesterol, soluble fiber, in general, would prevent the incidence of cardiovascular disease ^{30 , 58} . Results from a human study show that consuming grapefruit pectin (as a supplement) lowers total cholesterol and “bad” cholesterol (LDL) ³¹. For more details, see the Grapefruit (fiber) sheet in the Natural Health Products section.

Coumarin Auraptene
, a compound in the coumarin family , is found in grapefruit and citrus fruits , in their freshly squeezed juice, as well as in their bark ³² . Auraptene has the potential to decrease the proliferation of cancer cells ^{33 , 34} and the growth of tumors ³⁵ in animals. For the moment, these promising results cannot, however, be applied specifically to the consumption of grapefruit.

Main vitamins and minerals

Precautions

Consumption of grapefruit or grapefruit juice may increase or, less frequently, decrease the effects of certain medications . Indeed, substances contained in this fruit prevent an enzyme from metabolizing these drugs, which leads to an increase in their concentration in the blood, which can cause serious adverse reactions., sometimes fatal. Almost all classes of drugs are likely to interact with grapefruit: drugs for the treatment of cancer, depression, high cholesterol, high blood pressure, gastrointestinal reflux, heart problems, and other. Consuming as little as 250 ml of juice can, in some cases, cause effects that may last for 3 days or more. Taking the drug a few hours after consuming the grapefruit does not prevent unwanted effects. The tangelo , a hybrid of grapefruit, may also interact with certain medications.

Health Canada reminds you to refrain from consuming grapefruit or its juice unless you have consulted a doctor or pharmacist about the risks of adverse reactions. Note, however, that homemade squeezed juice would be less at risk than commercial juice. Indeed, the latter generally contains albedo (white skin under the rind of the fruit), in which are found mainly the substances that act on drugs. The grapefruit juice obtained directly by pressing the fruit contains very few of these substances.

To access other recipes, you can go to the CuisineAZ.com cooking recipe site, which offers, among other things, the following recipes: avocado and grapefruit salad , recipes based on pink grapefruit , shrimp salad and grapefruit

The citrus fruits are juicy when they are at room temperature. Therefore, it is best to take them out of the refrigerator for some time before consuming them. To extract as much juice as possible, roll the fruit with your hand on a work surface before passing it through the juicer.

• Cut the grapefruit in half and enjoy it as it is for breakfast, as a starter or as a dessert. Or, sweeten it and then place it under the grill for a few minutes before serving.
• Prepare a sauce to accompany the fruit salad by mixing honey, zest and grapefruit juice, a pinch of salt, ground nutmeg and poppy seeds.

• Add olive oil to this sauce to transform it into a vinaigrette that will go wonderfully with the fresh greens.
• Eat the squeezed juice or use it in sorbets, granita and ice cream.
• In the guacamole (avocado puree), replace the lemon juice with lime and grapefruit juice.
• Pieces of grapefruit sautéed in their juice are an unexpected accompaniment to a dish of mashed sweet potatoes with butter.
• In cooking, use the grapefruit zest like that of lemon, lime and orange.

• Prepare a salsa by mixing lime juice, olive oil, jalapeño pepper, red or green pepper, chopped onion, chopped grapefruit pieces and cilantro leaves.
• Pieces of grapefruit and tomato, strips of pepper, sliced ​​hard-boiled egg and crab make an excellent meal salad . Serve it on lettuce leaves, accompanied by a yogurt and mayonnaise sauce.
• Pieces of grapefruit and avocado coated with a vinaigrette make a delicious little starter . For a more elaborate dish, add blanched spinach and smoked fish (the ultimate: sturgeon), all topped with a tahini-based sauce, grapefruit juice and tofu.
• Let marinate chicken pieces in a mixture of grapefruit juice, garlic and hot pepper. Wipe the chicken, brown it in the oil, add the marinade and let reduce. Serve over fresh lettuce with a sauce of honey and grapefruit juice that you have reduced in the pan. Serve with sections of fresh fruit.
• Replace the chicken with shrimp, add sliced ​​green onions, red peppers and grapefruit sections and cook until the liquid is reduced.
• In Thai . Mix lime juice, fish sauce and sugar. Add cooked shrimp, grated coconut and coconut cream, then mix well. Add pieces of grapefruit last to avoid making them make too much juice.

Grapefruit flavored oil
In the trade, we have recently found olive oil flavored with citrus fruits, including grapefruit. The technique consists of pressing the two fruits together. The flavor of the resulting oil is usually too strong to be used in salad dressings. It is mainly used for marinades or cooking.

Keep

Refrigerator . The fruit can be stored for up to 6 weeks in the refrigerator, in a closed container, or 1 week at room temperature.

Dried . Dry the zest and keep it in an opaque, airtight container.

The term ”  grapefruit  ” dates from 1665 and comes from the Dutch pompelmoes , pompel , “thick” and limoes , “lemon”. ”  Pomelo  ” is a loan from the English pomelo (which also appears under the spelling pummelo ), itself derived from modern scientific Latin pomum melo meaning “apple melon”. The word has been introduced into our language in 1912, the botanical species that have been recognized as separate species at the XIX ^th  century.

A species conceived in America

The first seeds of the “real” grapefruit arriving in America were sown in Barbados, in the XVII ^th  century. However, the journey of this botanical species stops there. Indeed, a completely unforeseen marriage will take place between a young grapefruit tree resulting from these seeds and an orange tree whose ancestors had immigrated on American ground 2 centuries before. This unusual couple will generate a new species, the first of the Citrus genus to be born outside the limits of its territory, Southeast Asia. We will first name its fruit “forbidden fruit”, then ”  pomelo  ” ( grapefruit , in English). It is it that we commonly find today under the name of grapefruit.

The seeds of this new species were planted in Florida at the beginning of the XIX ^th  century by a Spanish emigrant. From them were born the great grapefruit orchards of the United States, a country where it is produced today more than anywhere in the world.

It took a certain vision and a lot of audacity on the part of the first American producers to cultivate a fruit which, at the time, was of no interest to anyone. Indeed, everywhere else, the tree was considered a simple object of curiosity, and its fruits rotted on the ground without being harvested. In the long run, Floridians will appreciate their flavor and freshness and will start consuming them.

Varied uses

In addition to fresh fruit and juice, grapefruit is used in the preparation of wine and vinegar . Albedo, the white part of the bark, is an excellent source of pectin . It also contains a bitter substance, naringin, used in “tonic” drinks, bitter chocolate and ice cream. Once de-bitter, this substance provides a sweetener that is 1,500 times sweeter than regular sugar. The essential oil extracted from the bark is used to flavor drinks. Of seed , a pulling edible oilwhich has the advantage of being unsaturated. Unfortunately, because of its pronounced bitterness and dark color, it has to be refined, making it a much less healthy product. Finally, the processing waste is added to the feed for farm animals.

The grapefruit seed extract has antimicrobial properties that can be used in agriculture, gardening or greenhouse. Particularly useful against molds, rust, mildew and other fungal diseases, it can also be used to fight insects, especially those without a shell, such as slugs or aphids. For shelled insects, it is mixed with a garlic extract and a hot pepper extract. It can be used, diluted, to water indoor plants.

It is especially in farms that the seed extract is useful. It is used to treat animals that suffer from infections caused by fungi (pulmonary or other). It is used to clean the udders of cows or horses’ hooves, as well as cages and stalls. It is added preventively to drinking water or feed to reduce the risk of contagion by pernicious bacteria, such as Escherichia  coli and Salmonella . It is even believed to be powerful enough to combat avian fever. It is known to stimulate the immune system of animals, which has the effect of reducing the need for drugs as well as mortality rates. It destroys bacteria, viruses and other intestinal parasites without attacking beneficial bacteria. By eliminating unwanted microorganisms, it stimulates the absorption of nutrients. Finally, administered in the form of a spray, it can treat oral conditions. For breeders of organic animals, who are not allowed to treat their animals with antibiotics, this is of the most precious help.