Grapefruit: nutrition facts and health benefits

Grapefruit

Pomelo and grapefruit should not be confused, although it is usual to designate the pomelo by calling it, wrongly, grapefruit. If they are cousins they both belong to the citrus family, which means citrus fruits are indeed different.

The botanical name of the grapefruit is Citrus × paradisi. It’s from the grapefruit. The fruit measures 11 to 17 cm in diameter, is pear-shaped. It has a skin which evolves between the yellow and the greenish. Its pulp is quite bitter and tart, not or little edible. It is grown in Thailand, Malaysia, Indonesia, Vietnam and the Caribbean.

Grapefruit history

The term “grapefruit” dates from 1665 and comes from the Dutch pompelmoes, pömpel, “thick” and limoes, “lemon”. “Pomelo” comes from English language (which also appears under the spelling pummelo), itself derived from the modern scientific Latin pomum melo meaning “melon apple”.

A species designed in America

The first seeds of the “true” grapefruit to arrive in America were said to have been sown in Barbados in the seventeenth century. However the trip of this botanical species stops there. Indeed, an unforeseen combination will take place between a young grapefruit from these seeds and an orange tree whose ancestors had immigrated to the American soil two centuries before. This unusual combination will spawn a new species, the first of the genus citrus to be born outside the boundaries of its territory, Southeast Asia. The fruit is first named “forbidden fruit”, then grapefruit. It’s this fruit which is now commonly found under the name of grapefruit.

 

The seeds of this new species were landed in Florida in the early nineteenth century by a Spanish emigrant. Of them, were born the great orchards of grapefruits of the United States, a country where it produces today more than anywhere in the world.

There was a need for 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 not strictly of interest to anyone. Indeed, everywhere else, the tree was considered a mere object of curiosity, and its fruits rotted on the ground without being harvested. In the long run, the Floridians appreciated the flavor and freshness and began to consume them.

Very varied uses

In addition to fresh fruit and juice, grapefruit is used to prepare wine and vinegar. The albedo, the white part of the bark, is an excellent source of pectin. It also contains a bitter substance, the naringin, used in “tonic” beverages, bitter chocolate and ice cream. Once their bitter flavor has been removed, this substance provides a sweetener which is 1 500 times sweeter than regular sugar. The essential oil extracted from the bark is used to aromatize beverages. An edible oil is made with the seeds which has the advantage of being unsaturated. Unfortunately, because of its pronounced bitterness and dark color, it must be refined, making it a much less healthy product. Finally, the waste of the processing is added to the feed of the farmed animals.

Grapefruit health profile

Grapefruit is a refreshing fruit with exceptional vitamin C content. The antioxidant compounds it contains would provide multiple health benefits, including cancer and cardiovascular disease.

The benefits of grapefruit

Cancer (prevention). Several studies have shown the consumption of citrus fruits, including grapefruit, would be related to the prevention of certain types of cancers, such as esophageal, stomach, colon, mouth and pharynx cancer. According to one of these studies, moderate consumption of citrus fruits (1-4 servings per week) would reduce the risk of cancers affecting the gastrointestinal tract and the upper part of the respiratory system. In the case of pancreatic cancer, the studies remain however contreversial.

A population study suggests that the daily consumption of citrus fruit coupled with a high consumption of green tea (1 cup and more per day) would be associated with a greater decrease in the cancer incidence.

The consumption of grapefruit could, according to a large-scale prospective study (population), reduce the risk of breast cancer. However, other studies have shown reverse results, or an absence links. In addition, researchers observed the incidence of lung cancer was lower among people who consumed white grapefruit.

Cancer (slowing progression). Antioxidant compounds contained in citrus fruits (limonoids) have shown anticancer effects in vitro and on animals. They could reduce the proliferation of cancer cells of breast, stomach, lung, mouth and the colon.

Blood lipids. In patients with high cholesterol, the consumption of 2 grapefruits per day would have the property of lowering cholesterol and blood triglyceride levels and increasing the antioxidant capacity in the blood. The consumption of red grapefruit would have more effect on the lipids (fatty) than the white grapefruit. In people with obesity, the consumption of ½ grapefruit (3 times per day) would not influence the lipid profile, but could play a role in the weight loss.

Several animal studies have shown that flavonoids and limonoids present in citrus juices have the property of lowering blood cholesterol. They could also increase HDL cholesterol (“good” cholesterol) and reduce triglycerides in the blood as well as cholesterol oxidation. It should be noted that, still in animals, the consumption of fresh grapefruit would be more advantageous for the lipid profile (blood levels of cholesterol and triglycerides) and antioxidant activity than taking a supplement of naringin (a flavonoid of grapefruit). In addition, some flavonoids could improve the elasticity of the blood vessel wall.

Blood glucose and weight loss. Among obese people with metabolic syndrome, grapefruit consumption (half a fruit per day before each meal for 12 weeks) resulted in significant weight loss compared to a control group (1.6 kg vs. 0.3 kg). It also significantly reduced their insulin resistance. Among diabetic animals, naringin supplements (a grapefruit flavonoid) significantly reduced blood sugar. This compound could play a role in the prevention of hyperglycemia.

Inflammation. Several studies have shown flavonoids of citrus fruits have anti-inflammatory properties. They inhibit the synthesis and activity of mediators involved in inflammation (arachidonic acid derivatives, prostaglandins E2, F2 and thromboxanes A2).

Other. Among other observed effects, 2 compounds present in citrus fruits (limonine and nomilie) inhibit the replication of the human immunodeficiency virus (HIV), in addition to inhibiting the protease activity of the virus. The nomilie and other citrus limonoids would strengthen the immune system among animals. These results are promising but have not been the subject of controlled clinical studies. It is therefore impossible for the moment to transpose these effects among humans.

Several prospective and epidemiological studies revealed that high consumption of fruits and vegetables reduced the risk of cardiovascular diseases, certain cancers and other chronic diseases.

What does the grapefruit contain?

Flavonoids

The grapefruit contains different types of flavonoids. These antioxidant compounds make it possible to neutralize free radicals of the body and thus prevent the onset of cardiovascular diseases, certain cancers and other chronic diseases. The grapefruit contains mostly naringin, but also the hesperetin in smaller quantity. It is the white part of the fruit peel which contains the most flavonoids, and the concentrations vary greatly depending on the crop.

The absorption and use of naringin and hesperetin among the human body differs from an individual to others. In any event, the ingestion of 1 cup (250 ml) of grapefruit juice provides a high concentration of flavonoids in the blood. The regular consumption of this juice could therefore have beneficial health effects.

 

Limonoids

The limonoids are found mainly in the citrus seeds, but also in their juice. According to their type, they can be responsible for the bitter flavor of the fruits which contain them or even be tasteless. The limonine is the main limonoid of the grapefruit. It would have, along with other limonoids present in citrus juices, the property of lowering blood cholesterol among animals.

These compounds would possess a certain antioxidant capacity. They could also lead to apoptosis of cancerous neuroblastic cells (embryonic nerve cells, then differentiated into neurons). Other studies suggest that citrus limonoids may prevent certain types of cancer among animals. For example, obacunone, a type of limonoid, has been found to be effective in reducing the incidence of colon tumors and in reducing the number of mouth tumors. However, there is currently no data on a similar effect among humans. The synergistic action of several limonoids between them, 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 of the carotenoid family. Grapefruits also contain other carotenoids, but in lesser quantities. Carotenoids have antioxidant properties. The consumption of carotenoid-rich foods would be related to a lesser risk of suffering from several diseases (for example, cancer and cardiovascular disease, although studies on the subject are controversial.)

Soluble fibers

Approximately 2/3 of the grapefruit fibers would be soluble fibers, such as pectin. They are found mainly in the bark and in the white membrane around the flesh (albedo). By their ability to reduce blood cholesterol, soluble fibers, in general, would prevent the incidence of cardiovascular diseases. The results of a study conducted among humans showed the consumption of grapefruit pectin (as a supplement) decreased total cholesterol and “bad” cholesterol (LDL).

Coumarin

The auraptene, a compound of the coumarin family, is found in grapefruit and citrus fruits, in their freshly squeezed juice, as well as in their bark. Auraptene would have the potential to decrease the proliferation of cancer cells and the growth of tumors among animals. For the time being, these promising results may not be applied specifically to the consumption of grapefruit.

Precautions

The consumption of grapefruit or grapefruit juice may lead to an increase or, less frequently, a decrease in the effects of certain medications. Indeed, substances contained in this fruit prevent an enzyme from metabolizing these drugs, resulting in increased concentration in the blood, which can cause serious, sometimes fatal, adverse reactions. Almost all classes of medications are likely to interact with grapefruit: medicines for the treatment of cancer, depression, hypercholesterolemia, high blood pressure, gastro-intestinal reflux, cardiac problems, and others. Consumption of as little as 250 ml of juice may, in some cases, results in effects may persist for 3 days or more. Taking the medicine a few hours after consuming the grapefruit does not allow avoiding the adverse effects. The tangelo, a grapefruit hybrid, could also interact with some medications.

Health authorities recall refraining from consuming grapefruits or their juices unless they have consulted a doctor or pharmacist about the risk of adverse reactions. Note however that the homemade squeezed juice would be less at risk than the commercial juice. In fact, the latter usually contains albedo (white skin under the skin of the fruit), in which most of the substances act on medicines are found. The grapefruit juice obtained directly by the pressure of the fruit contains only very few of these substances.

Choice and conservation

Keep

Refrigerator. The fruit keeps 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.

Ecology and environment

Grapefruit seed extract has antimicrobial properties can be used in agriculture, gardening or greenhouse. Particularly useful against mould, mildew and other fungal diseases, it can also be used to fight against insects, especially those having no carapace, such as slugs or aphids. For shell insects, it’s mixed with a garlic extract and a strong chilli extract. It can be used, diluted, to water the indoor plants.

It is especially in the farms the seed extract is useful. It helps to treat animals suffering from infections caused by fungi (pulmonary or other). It is used to clean the udders of cows or hoofs of horses, as well as cages and stalls. It’s added preventively to drinking water or to the feed to reduce contagion risk by pernicious bacteria, such as Escherichia coli and Salmonella. It is believed to be powerful enough to fight against avian fever. It is known to stimulate the immune system of animals, which has the effect of diminishing drug needs as well as mortality rates. It destroys bacteria, viruses and other intestinal pests without attacking the useful bacteria. By eliminating unwanted micro-organisms, it stimulates the absorption of nutrients. Finally, administered in the form of a pulverized spray, it can treat oral affections. For the breeders of biological animals, who are not allowed to treat their animals with antibiotics, this is the most valuable help.

 

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