Can eating whole grapefruit and drinking the juice induce weight loss, lower the risk of developing diabetes and its complications as well treat anaemia? Recent studies by Nigerian and Indian researchers have demonstrated the many therapeutic uses of grapefruit. CHUKWUMA MUANYA writes.
BOTANICALLY called Citrus paradisi, grapefruit is an important member of Citrus genus from family Rutaceae. It has been used as a folk medicine in many countries as antibacterial, antifungal, anti-inflammatory, antimicrobial, antioxidant, antiviral, astringent, and preservative. Several studies have also shown that grapefruit could be used for cancer prevention, cellular regeneration, lowering cholesterol, cleansing, detoxification, heart health maintenance, Lupus nephritis, rheumatoid arthritis and weight loss.
A recent study by Nigerian researchers from the Department of Pharmacology, Faculty of Basic Medical Sciences, Lagos State University College of Medicine, Ikeja, led by A.A. Adeneye, has found that the seed extract of Citrus paradisi is effective in the treatment of blood deficiency.
The study published in Biomedical Research is titled “Haematopoetic effect of methanol seed extract of Citrus paradisi Macfad (grape fruit) in Wistar rats.”
The study reads: “Anaemia remains one of the major global health problems affecting more than 30 per cent of world’s population, with higher prevalence among children and adults of low socio-economic class. In developing countries, most common forms of anaemia are nutritional, pregnancy-related, secondary to acute febrile illness or parasitic infestation.
“Hereditary haemoglobinopathies such as sickle cell disease and thalassemia, which are associated with recurrent haemolysis are also important causes of childhood anaemia. A few cases are drug-related particularly with the use of drugs such as sulphonamides, dapsone and methyl dopa. Other rare causes of anaemia include connective tissue disorders such as rheumatoid arthritis, polyarthritis nodosa, Wegener’s granulomatosis, progressive systemic sclerosis (scleroderma), etc. “Despite availability of array of orthodox treatments for anaemia, there is still a heavy dependence on herbal alternatives for its treatment, particularly, the rural dwellers and urban residents of low socio-economic class. While a good number of locally used herbal remedies have been scientifically evaluated and validated but a large number of these remedies remain scientifically unevaluated. One of this is the dried seeds of Citrus paradisi, which has ancestral use in the local management of diabetes, obesity, blood deficiency and as immune booster.
“The present study was undertaken to evaluate the blood forming effects of (100 per cent methanol seed extract) of Citrus paradisi in adult Wistar rats for 30 days as a way of evaluating its traditional use in the treatment of blood deficiencies. Acute oral toxicity study was also conducted using limit dose test of the Up and Down Procedure statistical program (AOT425PgmStat, Version 1.0) at a dose of 2000 mg/kg body weight/oral route.
“Results of the present study showed that chronic administration of methanol seed extract of Citrus paradisi to treated rats resulted in significant, dose related elevations in the haematological parameters investigated except the neutrophil and monocyte differentials. Literature has shown that oral ingestion of medicinal compounds or drugs can alter the normal range of haematological parameters.“These alterations could either be positive or negative. In this study, most of the effects recorded for the extract were positive except for its suppressive effects on the neutrophil and monocyte differentials. This suggests that the extract may be selectively toxic to these leucocyte lineages. This postulation, however, requires validation.”
Another new research at the University of California (UC), Berkeley, United States, found that mice fed a high-fat diet gained 18 percent less weight when they drank clarified, no-pulp grapefruit juice compared with a control group of mice that drank water. The new study published last week in the peer-reviewed journal PLOS ONE found that juice-drinking mice also showed improved levels of glucose, insulin and a type of fat called triacylglycerol compared with their water-drinking counterparts.
The authors of the UC Berkeley study randomly divided mice into six groups, including a control group that drank only water. Those drinking grapefruit juice got a mixture diluted with water at different concentrations, and sweetened slightly with saccharin to counteract grapefruit’s bitterness. The researchers also added glucose and artificial sweeteners to the control group’s water so that it would match the calorie and saccharin content of the grapefruit juice.
At the end of the study period, the mice that ate the high-fat diet and drank diluted grapefruit juice not only gained less weight than their control counterparts, they also had a 13 to 17 percent decrease in blood glucose levels and a threefold decrease in insulin levels, which reveals greater sensitivity to insulin. (In Type 2 diabetes, the pancreas makes extra insulin to compensate for increased resistance to the hormone.)
The researchers gave one group of mice naringin, a bioactive compound in grapefruit juice that has been identified as a key agent in weight loss, and another group metformin, a glucose-lowering drug often prescribed for those with Type 2 diabetes. The mice were fed a diet that was either 60 percent fat or 10 percent fat for 100 days, and their metabolic health was monitored throughout the study.
The group of high-fat-diet mice that received naringin had lower blood glucose levels than the control group, but there was no effect on weight, suggesting that some other ingredient in grapefruit juice is also beneficial. The study did not find as big an impact on mice that ate a low-fat diet. Those that drank the grapefruit juice saw a two-fold decrease in insulin levels, but there was no significant change in weight or other metabolic variables.
The researchers said they ruled out the typical explanations for weight loss in their study. It wasn’t the amount of food consumed, since the ingested calories among the different groups were about the same. The level of activity and body temperatures were comparable, and the authors even checked the calories eliminated in the feces of the mice to check for problems with the body’s absorption of nutrients.
The UC Berkeley researchers were led by an associate professor of nutritional sciences and toxicology, Andreas Stahl, and professor and chair of nutritional sciences and toxicology, Prof. Joseph Napoli: “I was surprised by the findings. We even re-checked the calibration of our glucose sensors, and we got the same results over and over again.”
Napolli added: “We see all sorts of scams about nutrition. But these results, based on controlled experiments, warrant further study of the potential health-promoting properties of grapefruit juice. “The grapefruit juice lowered blood glucose to the same degree as metformin. That means a natural fruit drink lowered glucose levels as effectively as a prescription drug.” Stahl said: “There are many active compounds in grapefruit juice, and we don’t always understand how all those compounds work. The effects were more subtle for the low-fat diet group.
“Mice are incredibly healthy animals with naturally low levels of bad cholesterol. So if they are eating a healthy, low-fat diet, it will take more to see a significant effect on their health. Basically, we couldn’t see a smoking gun that could explain why or how grapefruit juice affects weight gain.”
The researchers said they hope to continue the investigation into grapefruit juice. “Obesity and insulin resistance are such huge problems in our society, “said Stahl. “These data provide impetus to carry out more studies.” Meanwhile, Nigerian researchers have also demonstrated the effectiveness of grapefruit (Citrus paradisi) seeds in treating urinary tract infections.
The study published in Pomelo Journal of Alternative Complementary Medicine by Oyelami O. A., Agbakwuru E. A., Adeyemi L. A., Adedeji G. B. concluded: “These preliminary data thus suggest an antibacterial characteristic of dried or fresh grapefruit seeds (C. paradisi) when taken at a dosage of five-to-six seeds every eight hours, that is comparable to that of proven antibacterial drugs.”
The study reads: “Three middle-aged males and one female were diagnosed as having urinary tract infections (UTIs) between 2001 and 2003 in the Wesley Guild Hospital, Ilesa, a unit of Obafemi Awolowo University Teaching Hospitals Complex, Ile Ife, Osun State, Nigeria. “Of the four patients, only the female was asymptomatic. The three males had Pseudomonas aeruginosa, Klebsiella species, and Staphylococcus aureus, respectively, in their urine samples, while the female had Escherichia coli.
All 4 patients were treated with grapefruit seeds (Citrus paradisi) orally for two weeks, and they all responded satisfactorily to the treatment except the man with P. aeruginosa isolate. “However, the initial profuse growth of Pseudomonas isolate in the patient that was resistant to gentamicin, tarivid, and augmentin later subsided to mild growth with reversal of the antibiotic resistance pattern after 2 weeks’ treatment with grapefruit seeds.”
Another study published recently in American Journal of Plant Sciences from the Department of Biochemistry, Faculty of Basic Medical Sciences, College of Medicine, University of Lagos, concluded: “This study has shown that the oil extract of grape peels from Nigeria contains some useful potential antibiotic principles that are inhibitory to a broad spectrum of cli- nical isolates. Thus, it may be considered as a natural source of antimicrobials for therapeutic purposes.” The study is titled “Essential Oil of Grape Fruit (Citrus paradisi) Peels and Its Antimicrobial Activities.”
Yet another study published in African Journal of Pharmacy and Pharmacology by Nigerian researchers from the Department of Anatomy, Lagos State University College of Medicine (LASUCOM), Ikeja, Lagos, Department of Anatomy, University of Ilorin, Ilorin, Kwara State, Department of Anatomy, Afe Babalola University, Ado-Ekiti, Ekiti, and Department of Anatomy, Ladoke Akintola University of Technology, Ogbomosho, Oyo, concluded: “It is concluded from the results obtained in this study that the juice of C. paradisi fruit (grapefruit) possesses protective and even rejuvinative effects on the liver of Wistar rats at a lower dose, but it is deleterious to the liver at higher doses.” The study is titled “The hepato-rejuvinative and hepato-toxic capabilities of Citrus paradisi Macfad fruit juice in Rattus Norvegicus.”
An overview of the pharmacological potentials of Citrus paradisi published in International Journal of Phytotherapy Research by India researchers from University Centre of Excellence in Research, BFUHS, Faridkot, Guru Gobind Singh Medical College, BFUHS, Faridkot, Akal College of Pharmacy and Technical Education, Mastuana Sahib, Department of Biochemistry, PGIMER, Chandigarh, and Vaish Institute of Pharmaceutical Education and Research, Rohtak, highlighted the pharmacological activities of this plant for various therapeutic uses. The researchers concluded: “Current world-wide interest in traditional medicine has led to the rapid development and studies of many remedies employed by various ethnic groups of the world. Scientists from divergent fields are investigating new plants with an eye on their pharmacological usefulness.
“More of these compounds should be subjected to animal and human studies to determine their effectiveness in whole organism systems, including in particular toxicity studies as well as an examination of their effects in patients. It would be advantageous to standardize methods of extraction and in vitro testing so that the search could be more systematic and interpretation of results would be facilitated regarding various disease treatment.”
Phytochemical analysis – The approximate yield of essential oil from citrus paradise is 3.9 per cent which contains open chain hydrocarbons, alcohols, aldehydes, ketones, esters and alpha-terpenoids. As a relatively new food, the grapefruit has made great advances in the past 75 years. The sections are commonly used in fruit cups or fruit salads, in gelatins or puddings and tarts.
In Australia, grapefruit is commercially processed as marmalade. It may also be made into jelly. The juice is marketed as a beverage fresh, canned, or dehydrated as powder, or concentrated and frozen. It can be made into excellent vinegar or carefully fermented as wine.
Grapefruit peel is candied and is an important source of pectin for the preservation of other fruits. The peel oil, expressed or distilled, is commonly employed in soft-drink flavoring, after the removal of 50 per cent of the monoterpenes. Naringin, extracted from the inner peel is used as a bitter in “tonic” beverages, bitter chocolate, ice cream and ices. Keeping in view its varied use, it is pertinent to explore medicinal importance of this plant. This compilation is an effort by authors to provide an opportunity to scientific fraternity to get all the information related to this plant at a single platform so that new formulations with multiple uses can be designed.
Chemical constituents – Citrus peel is rich in flavanone glycosides and polymethoxyflavones. Citrus paradisi the most interesting for isolation. The results show that the Star Ruby grapefruit stand out for their high contents of naringin. The presence of the polymethoxyflavones nobiletin, heptamethoxyflavone and tangeretin, could be ascertained in all the grapefruit varieties analyzed. Higher polymethoxyflavone levels were recorded in orange, with Valencia Late showing the greatest nobiletin, sinensetin and tangeretin contents and Navelate the highest heptamethoxyflavone levels.
Naringin [the 7-β-neohesperidoside of narigenin (4’, 5, 7-trihydroxiflavananone)] is found in citrus plants and is most abundant in Citrus paradisi species. The hydro-distilled essential oil content from fresh-, ambient and oven-dried peels of C. paradisi ranged 0.20-0.40 g/100 g . From the gas chromatography (GC) and GC/MS studied the essential oil shows the presence of 23 constituents out of which some constituents were identified as alpha- pinene (0.44 per cent), beta-pinene (2.51 per cent), limonene (81.6 per cent), p-cymene (3.6 per cent), linalyl acetate (5.20 per cent), sabinene (1.02 per cent), 4-terpineol (0.389 per cent), alpha-terpineol (0.31 per cent), alpha-thugene (0.28 per cent), ctanol (0.26 per cent), 1,8- cineol (0.42 per cent), Geraniol (0.21 per cent) and decanal (0.16 per cent).
Grapefruit pulp contains significant levels of vitamin C; potassium, folate, calcium, and iron. The pink and red varieties also contain beta-carotene and lycopene, antioxidants that the body can convert to vitamin A. Other protective plant chemicals found in grapefruits include phenolic acid, limonoids, terpenes, monoterpenes, D-glucaric acid and flavonoids including hesperetin and naringenin. Grapefruit oil contains: nonanal, nootkatone, beta-Pinene, alpha- phellandrene, 3-carene, ocimene, octanol, trans-linalool oxide, cis-p-mentha-2, 8- dien-1-ol, alpha-pinene, limonene, linalool, Geraniol, citronellal, alpha- terpineol, neral, dodecanal, and alpha- humulene.
Anti-HIV – The 6, 7-dihydroxy-bergamottin of Citrus paradisi enhances bioavailability of HIV protease inhibitor (saquinavar) by inhibiting cytochrome P450 iso-enzyme 3A4 in liver and gut.
Anti-inflammatory effect – The antiinflammatory effect of Anarcadium occidentale stem-bark aqueous extract alone and in combination with grapefruit (Citrus paradisi) juice was investigated on fresh egg albumin-induced rat paw edema. Like diclofenac (100 mg/kg p.o.), aqueous extract of A. occidentale stem-bark (800 mg/kg p.o.) produced time-related, sustained and significant reduction of the fresh egg albumin-induced acute inflammation of the rat hind paw.
However, the anti-inflammatory effect of the plant extract was found to be approximately 8-15 times less than that of diclofenac. Co-administration of grapefruit juice (5 ml/kg p.o.) with A. occidentale stem-bark aqueous extract (800 mg/kg p.o.) or diclofenac (100 mg/kg p.o.) significantly potentiated the anti-inflammatory effects of the crude plant extract and diclofenac on fresh egg albumin-induced rat paw edema.
Antiatherogenic – Naringenin belongs to the class of flavonoids called the flavanones. The flavanones are abundant in citrus fruits such as grapefruit (Citrus paradisi) and the oranges (Citrus sinensis). (To be continued)
Culled from TheGuardian (Nov 2014)