Grapefruit (Citrus paradisi) Research

Latin Name: Citrus paradisi

Family: Rutaceae

RESEARCH

The listings of research below represent a compilation of scientific articles found on the species, with a very brief overview description of each article/study.  Research found is catalogued by therapeutic action.  This categorized compilation of research articles does not necessarily imply that there are adequate results to demonstrate safe and/or effective human use.

GENERAL

• This is an overview of the therapeutic actions of grapefruit.  From: More, S., Sathe, S., Sonawane, A., Jadhav, A., & Kadam, V. (2013). CITRUS PARADISI: AN OVERVIEW. Indo American Journal of Pharmaceutical Research, 3(10), 8070-8077.
• This article provides an overview of grapefruit.  From:  Gupta, V., Kohli, K., Ghaiye, P., Bansal, P., & Lather, A. (2011). Pharmacological potentials of citrus paradise-An overview. Int J Phytother Res, 1, 8-17.
• Petersen, D. (2015). Aromatherapy materia medica.  Essential oil monographs.  American College of Healthcare Sciences.
• WebMD. (n.d.). Grapefruit.  Retrieved in December, 2015.  Retrieved from www.webmd.com
• Tisserand, R. & Young, R.  Essential Oil Safety. Second Edition.  Churchill, Livingstone, Elsevier.
• Guzmán Gutiérrez, S. L., Reyes Chilpa, R., & Bonilla Jaime, H. (2014). Medicinal plants for the treatment of “nervios”, anxiety, and depression in Mexican Traditional Medicine. Revista Brasileira de Farmacognosia, 24(5), 591-608.
• Scientific research on the therapeutic actions of Citrus ssp were reviewed.  Grapefruit showed cytotoxic, antibacterial, antifungal, larvicidal, and weight loss activities.  From:  Dosoky, N., & Setzer, W. (2018). Biological activities and safety of Citrus spp. essential oils. International journal of molecular sciences, 19(7), 1966.
• Osman, A. (2019). Citrus Oils. In Fruit Oils: Chemistry and Functionality (pp. 521-540). Springer, Cham.
• A review of research on the bioactivity of citrus peels was provided and included antioxidant, anti-diabetic, cardioprotective, neuroprotective and anticancer possibilities. From: Ademosun, A. O., Oboh, G., Olasehinde, T. A., & Adeoyo, O. O. (2018). From folk medicine to functional food: a review on the bioactive components and pharmacological properties of citrus peels. Oriental Pharmacy and Experimental Medicine, 18(1), 9-20.
• Furocoumarins have shown in research to have significant antimicrobial, insecticidal, and cancer inhibiting activity. However, there is also a phototoxic effect and there can be interference with drug metabolism. Furocoumarins are found in grapefruit, lemon, lime, orange, carrot, celery, parsnip, dill, parsley, cilantro, cumin, coriander, turnip, and fig. From: Melough, M. M., Cho, E., & Chun, O. K. (2018). Furocoumarins: a review of biochemical activities, dietary sources and intake, and potential health risks. Food and Chemical Toxicology, 113, 99-107.

SAFETY

• Dilute and avoid sun exposure with topical use. Topical use can cause photosensitation, skin irritation and contact dermatitis.   From:  National Asosciation for Holistic Aromatherapy: Safety Information / Photosensitization http://naha.org/explore-aromatherapy/safety/       A safe dilution ratio is 1-2% in a carrier oil.  This would equal about 6-12 drops in an ounce of carrier oil.
• Avoid topically on damaged or sensitive skin. Grapefruit has a toxic rating of I, with skin patch test required, with constituents of furocoumarins and d-limonene.  From:  Petersen, D. (2015). Aromatherapy materia medica.  Essential oil monographs.  American College of Healthcare Sciences.
• Essential oil Not for internal use. Consult a Physician or expert with internal use.
• Not for use during pregnancy or lactation: due to insufficent medical evidence.  From:  Natural Medicines (2017).  Grapefruit Monograph.  Retrieved in August, 2017.  Retrieved from www.naturalmedicines.com
• Contact Physician before use with medical conditions. Some conditions include:
• Hypertension  – The limonene constituent may have blood pressure elevating activity.
  • Zitron, E., Scholz, E., Owen, R. W., Lück, S., Kiesecker, C., Thomas, D., … & Katus, H. A. (2005). QTc prolongation by grapefruit juice and its potential pharmacological basis. Circulation, 111(7), 835-838.
  • Piccirillo, G., Magrì, D., Matera, S., Magnanti, M., Pasquazzi, E., Schifano, E., … & Ghiselli, A. (2008). Effects of pink grapefruit juice on QT variability in patients with dilated or hypertensive cardiomyopathy and in healthy subjects. Translational Research, 151(5), 267-272.
• Hormone cancers and conditions – Grapefruit juice may reduce estrogen metabolism resulting in increased estrogen amounts in the body.
  • Large grapefruit juice intake may increase the risk of breast cancer in post menopausal women relauted to an oestrogenic effect.  From:  Monroe, K. R., Murphy, S. P., Kolonel, L. N., & Pike, M. C. (2007). Prospective study of grapefruit intake and risk of breast cancer in postmenopausal women: the Multiethnic Cohort Study. British journal of cancer, 97(3), 440.
• Drug interactions: Grapefruit has several well documented drug interactions; discuss with Physician before use. Drugs include but are not limited to: Artemether, Buspirone, Carbamazepine, Carvedilol, Cisapride, Clomipramine, Cyclosporine, Dextromethorphan, Estrogens, Etoposide, Itraconazole, Methylprednisolone, Praziquantel, Quinidine, Scopolamine, Sildenafil,  Terfenadine, Caffeine, Erythromycin,    Fexofenadine, Losartan, Saquinavir,  Theophylline, Warfarin, medications changed by the liver, medications for high blood pressure, medications for lowering cholesterol, and sedative medications.  From:  Natural Medicines (2017).  Grapefruit monograph.  Retieved in August, 2017.  Retrieved from www.naturalmedicines.therapeuticresearch.com.
• Avoid excessive use: Potential side effects can include heart arrhythmias, skin irritation, sensitization, kindey stones, possible increased risk of hormone related cancers, and reduced potassium levels.  From:  From:  Natural Medicines (2017).  Grapefruit monograph.  Retieved in August, 2017.  Retrieved from www.naturalmedicines.therapeuticresearch.com.
• Flammable.Keep out of reach of children and pets.

ANTIMICROBIAL / ANTIBACTERIAL / ANTIFUNGAL / ANTI-VIRAL

• Various extracts of grapefruit peel were antimicrobial, antibacterial, and antifungal against tested pathogenic disease organisms. From: Okunowo, W. O., Oyedeji, O., Afolabi, L. O., & Matanmi, E. (2013). Essential oil of grape fruit (Citrus paradisi) peels and its antimicrobial activities. American Journal of Plant Sciences, 4(07), 1.
• The antimicrobial activity of essential oils extracted from Citrus maxima (grapefruit), Citrus aurantium (bitter orange), Citrus aurantifolia (key lime) and Limonia acidissima (woodapple) were assessed against five gram-positive and ten gram-negative bacteria, and a fungal strain: Candida albicans.  C. maxima and C. aurantifolia demonstrated antimicrobial properties, even when compared with positive controls antibiotics of ciprofloxacin and ketoconazole.  The organisms most sensitive to the essential oils were Acinetobacter baumannii and those most resistant were Enterococcus faecalis and Pseudomonas aeruginosa.  From:  Chintaluri, A. K., Komarraju, A. L., Chintaluri, V. K., & Vemulapalli, B. (2015). Comparative study of antimicrobial activity of essential oils of selected plants of Rutaceae and TLC bioautographic studies for detection of bioactive compounds. Journal of Essential Oil Research, 27(1), 9-16.
• Citrus limon (lemon), Citrus paradisi (grapefruit), Citrus bergamia (bergamot), Citrus aurantium (bitter orange), Citrus sinensis (sweet orange), and Citrus reticulata (mandarin) showed antimicrobial activity against multiple bacteria, fungi, and candida species in vitro.  From:  Kirbaşlar, F. G., Tavman, A., Dülger, B., & Türker, G. (2009). Antimicrobial activity of Turkish Citrus peel oils. Pak J Bot, 41(6), 3207-12.
• Antifungal, anti-aflatoxigenic and antioxidant activity of Citrus maxima and Citrus sinensis essential oils were analyzed.  From:  Singh, P., Shukla, R., Prakash, B., Kumar, A., Singh, S., Mishra, P. K., & Dubey, N. K. (2010). Chemical profile, antifungal, antia  flatoxigenic and antioxidant activity of Citrus maxima Burm. and Citrus sinensis (L.) Osbeck essential oils and their cyclic monoterpene, DL-limonene. Food and Chemical Toxicology, 48(6), 1734-1740.
• Citrus fruits: Citrus sinensis (orange), C. aurantium (bitter orange), C. deliciosa (mandaran), C. paradisi (grapefruit), and C. limon (lemon) were tested and showed antimicrobial activity against P. digitatum and P. italicum growth. From: Caccioni, D. R., Guizzardi, M., Biondi, D. M., Renda, A., & Ruberto, G. (1998). Relationship between volatile components of citrus fruit essential oils and antimicrobial action on Penicillium digitatum and penicillium italicum. International journal of food microbiology, 43(1-2), 73-79.
• Grapefruit and other plants showed anti-HIV potential.  From:  Chinsembu, K. C., & Hedimbi, M. (2010). Ethnomedicinal plants and other natural products with anti-HIV active compounds and their putative modes of action. Int J Biotechnol Mol Biol Res, 1(6), 74-91.
• The author discussed the antimicrobial evidence on grapefruit extract.  From:  Cvetnic, Z. D. E. N. K. A., & Vladimir-Knezevic, S. A. N. D. A. (2004). Antimicrobial activity of grapefruit seed and pulp ethanolic extract. Acta Pharm, 54(3), 243-250.
• C. paradisi inhibited the bacterial strains of P. larvae, a honey bee pathogen. From:  Fuselli, S. R., de la Rosa, S. B. G., Eguaras, M. J., & Fritz, R. (2008). Chemical composition and antimicrobial activity of Citrus essences on honeybee bacterial pathogen Paenibacillus larvae, the causal agent of American foulbrood. World Journal of Microbiology and Biotechnology, 24(10), 2067-2072.
• Grapefruit juice increases the bioavailability of saquinavir, an HIV protease inhibitor.  From:  Kupferschmidt, H. H., Fattinger, K. E., Ha, H. R., Follath, F., & Krähenbühl, S. (1998). Grapefruit juice enhances the bioavailability of the HIV protease inhibitor saquinavir in man. British journal of clinical pharmacology, 45(4), 355-359.
• Antibacterial action of grapefruit was assessed and was more effective against Gram-positive than Gram-negative bacteria.  From:  Negi, P., & Jayaprakasha, G. (2001). Antibacterial activity of grapefruit (Citrus paradisi) peel extracts. European Food Research and Technology, 213(6), 484-487.
• Lemon, mandarin, grapefruit, and orange oils were antifungal against food spoilage molds.  From:  Viuda-Martos, M., Ruiz-Navajas, Y., Fernández-López, J., & Pérez-Álvarez, J. (2008). Antifungal activity of lemon (Citrus lemon L.), mandarin (Citrus reticulata L.), grapefruit (Citrus paradisi L.) and orange (Citrus sinensis L.) essential oils. Food control, 19(12), 1130-1138.
• Orange, grapefruit, mandarin, and tangarine essential oils demonstrated antioxidant and antimicrobial actions in vitro.  From:  Javed, S., Javaid, A., Nawaz, S., Saeed, M. K., Mahmood, Z., Siddiqui, S. Z., & Ahmad, R. (2014). Phytochemistry, GC-MS analysis, antioxidant and antimicrobial potential of essential oil from five citrus species. Journal of Agricultural Science, 6(3), 201.
• Bay, cinnamon, grapefruit, lemongrass, thyme, clary sage, wintergreen, clove, allspice, and camphor essential oils showed varying degrees of inhibition against MRSA and MSSA bacterial samples from hospital patients. From:  Sharma, P. U. J. A., Mack, J. P., & Rojtman, A. (2013). Ten highly effective essential oils inhibit growth of methicillin resistant staphylococcus aureus (MRSA) and methicillin sensitive staphylococcus aureus (MSSA). Int. J. Pharm. Pharmacol, 5(1), 52-54.
• Grapefruit extracts showed antibacterial and antimicrobial activities in vitro. From: Mushtaq, H. (2018). A Study of Antimicrobial Effects of Citrus Paradisi ‘Grape Fruit’. Annals of PIMS-Shaheed Zulfiqar Ali Bhutto Medical University, 14(2), 185-190.
• Citrus essential oils showed a variety of effectiveness against foodborne pathogens in vitro. From: Restuccia, C., Conti, G. O., Zuccarello, P., Parafati, L., Cristaldi, A., & Ferrante, M. (2019). Efficacy of different citrus essential oils to inhibit the growth and B1 aflatoxin biosynthesis of Aspergillus flavus. Environmental Science and Pollution Research, 1-10.

ANTIOXIDANT

• In a summary of research, it was concluded that flavonoids from citrus fruits have antioxidant activity that may help reduce disease like cancer and inflammation. From: Asjad, H. M. M., Akhtar, M. S., Bashir, S., Din, B., Gulzar, F., Khalid, R., & Asad, M. (2013). Phenol, flavonoid contents and antioxidant activity of six common citrus plants in Pakistan. Journal of Pharmaceutical and Cosmetic Sciences, 1(1), 1-5.
• In a review of research grapefruit and its component, naringin has shown antioxidant, lipid-lowering, antihypertensive, antidiabetic, cardiac protective, and anti-obesity effects. From: Razavi, B. M., & Hosseinzadeh, H. (2019). A Review of the Effects of Citrus paradisi (Grapefruit) and Its Flavonoids, Naringin, and Naringenin in Metabolic Syndrome. In Bioactive Food as Dietary Interventions for Diabetes (pp. 515-543). Academic Press.
• Antioxidant activity of two grapefruit varieties was demonstrated in vitro. From: Sicari, V., Pellicanò, T. M., Giuffrè, A. M., Zappia, C., Capocasale, M., & Poiana, M. (2018). Physical chemical properties and antioxidant capacities of grapefruit juice (Citrus paradisi) extracted from two different varieties. International Food Research Journal, 25(5).
• Antifungal, anti-aflatoxigenic and antioxidant activity of Citrus maxima and Citrus sinensis essential oils were analyzed.  From:  Singh, P., Shukla, R., Prakash, B., Kumar, A., Singh, S., Mishra, P. K., & Dubey, N. K. (2010). Chemical profile, antifungal, antia  flatoxigenic and antioxidant activity of Citrus maxima Burm. and Citrus sinensis (L.) Osbeck essential oils and their cyclic monoterpene, DL-limonene. Food and Chemical Toxicology, 48(6), 1734-1740.
• Orange, grapefruit, mandarin, and tangarine essential oils demonstrated antioxidant and antimicrobial actions in vitro.  From:  Javed, S., Javaid, A., Nawaz, S., Saeed, M. K., Mahmood, Z., Siddiqui, S. Z., & Ahmad, R. (2014). Phytochemistry, GC-MS analysis, antioxidant and antimicrobial potential of essential oil from five citrus species. Journal of Agricultural Science, 6(3), 201.
• Flavonoids and other constituents isolated from citrus demonstrated antioxidant activities in vitro. From: Yu, J., Wang, L., Walzem, R. L., Miller, E. G., Pike, L. M., & Patil, B. S. (2005). Antioxidant activity of citrus limonoids, flavonoids, and coumarins. Journal of agricultural and food chemistry, 53(6), 2009-2014.
• In a summary of research, hesperidin is a bioflavonoid found in high concentrations in citrus fruit with a significant anti-inflammatory and antioxidant effect. From: Tejada, S., Pinya, S., Martorell, M., Capó, X., Tur, J. A., Pons, A., & Sureda, A. (2018). Potential anti-inflammatory effects of hesperidin from the genus Citrus. Current medicinal chemistry, 25(37), 4929-4945.
• Phenolic components from citrus fruits showed antioxidant, hypoglycemic, hypotensive activities in vitro.   From: Alu’Datt, M. H., Rababah, T., Alhamad, M. N., Al-Mahasneh, M. A., Ereifej, K., Al-Karaki, G., … & Ghozlan, K. A. (2017). Profiles of free and bound phenolics extracted from Citrus fruits and their roles in biological systems: content, and antioxidant, anti-diabetic and anti-hypertensive properties. Food & function, 8(9), 3187-3197.

PRESERVATIVE

• Lemon, mandarin, grapefruit, and orange oils were antifungal against food spoilage molds.  From:  Viuda-Martos, M., Ruiz-Navajas, Y., Fernández-López, J., & Pérez-Álvarez, J. (2008). Antifungal activity of lemon (Citrus lemon L.), mandarin (Citrus reticulata L.), grapefruit (Citrus paradisi L.) and orange (Citrus sinensis L.) essential oils. Food control, 19(12), 1130-1138.
• Citrus essential oils showed a variety of effectiveness against foodborne pathogens in vitro. From: Restuccia, C., Conti, G. O., Zuccarello, P., Parafati, L., Cristaldi, A., & Ferrante, M. (2019). Efficacy of different citrus essential oils to inhibit the growth and B1 aflatoxin biosynthesis of Aspergillus flavus. Environmental Science and Pollution Research, 1-10.

CARDIAC HEALTH / BLOOD HEALTH

• In this systematic review of over 100 randomized controlled human trials, grapefruit consumption significantly reduced systolic blood pressure, but could not definitively demonstrate weight loss.  More human studies are needed.  From:  Onakpoya, I., O’Sullivan, J., Heneghan, C., & Thompson, M. (2017). The effect of grapefruits (Citrus paradisi) on body weight and cardiovascular risk factors: A systematic review and meta-analysis of randomized clinical trials. Critical reviews in food science and nutrition, 57(3), 602-612.
• Grapefruit extract improved blood count levels in rats.  From: Adeneye, A. A. (2008). Haematopoetic effect of methanol seed extract of Citrus paradisi Macfad (grapefruit) in Wistar rats. Biomed Res, 19(1), 23-26.
• Coronary vasodilator and hypotensive effects of Citrus paradisi peel extract were demonstrated.  From:  Díaz‐Juárez, J. A., Tenorio‐López, F. A., Zarco‐Olvera, G., Valle‐Mondragón, L. D., Torres‐Narváez, J. C., & Pastelín‐Hernández, G. (2009). Effect of Citrus paradisi extract and juice on arterial pressure both in vitro and in vivo. Phytotherapy Research, 23(7), 948-954.
• In a review of research grapefruit and its component, naringin has shown antioxidant, lipid-lowering, antihypertensive, antidiabetic, cardiac protective, and anti-obesity effects. From: Razavi, B. M., & Hosseinzadeh, H. (2019). A Review of the Effects of Citrus paradisi (Grapefruit) and Its Flavonoids, Naringin, and Naringenin in Metabolic Syndrome. In Bioactive Food as Dietary Interventions for Diabetes (pp. 515-543). Academic Press.
• Citrus paradisi juice decreased diastolic arterial pressure and systolic arterial pressure in both normal and hypertensive animals. From: Díaz‐Juárez, J. A., Tenorio‐López, F. A., Zarco‐Olvera, G., Valle‐Mondragón, L. D., Torres‐Narváez, J. C., & Pastelín‐Hernández, G. (2009). Effect of Citrus paradisi extract and juice on arterial pressure both in vitro and in vivo. Phytotherapy Research: An International Journal Devoted to Pharmacological and Toxicological Evaluation of Natural Product Derivatives, 23(7), 948-954.
• Phenolic components from citrus fruits showed antioxidant, hypoglycemic, hypotensive activities in vitro.   From: Alu’Datt, M. H., Rababah, T., Alhamad, M. N., Al-Mahasneh, M. A., Ereifej, K., Al-Karaki, G., … & Ghozlan, K. A. (2017). Profiles of free and bound phenolics extracted from Citrus fruits and their roles in biological systems: content, and antioxidant, anti-diabetic and anti-hypertensive properties. Food & function, 8(9), 3187-3197.

HEPATOPROTECTIVE

• Grapefruit showed anti-genotoxic, hepatoprotective capabilities.  From: Alvarez-Gonzalez, I., Mojica, R., Madrigal-Bujaidar, E., Camacho-Carranza, R., Escobar-García, D., & Espinosa-Aguirre, J. J. (2011). The antigenotoxic effects of grapefruit juice on the damage induced by benzo (a) pyrene and evaluation of its interaction with hepatic and intestinal Cytochrome P450 (Cyp) 1a1. Food and Chemical Toxicology, 49(4), 807-811.

DIGESTIVE AID

• In a review of research, eating citrus fruits help reduce inflammatory bowel disease. From: Musumeci, L., Maugeri, A., Cirmi, S., Lombardo, G. E., Russo, C., Gangemi, S., … & Navarra, M. (2019). Citrus fruits and their flavonoids in inflammatory bowel disease: an overview. Natural product research, 1-15.
• In a review of research, flavones from citrus fruits can help improve digestive health. From: Stevens, Y., Rymenant, E. V., Grootaert, C., Camp, J. V., Possemiers, S., Masclee, A., & Jonkers, D. (2019). The Intestinal Fate of Citrus Flavanones and Their Effects on Gastrointestinal Health. Nutrients, 11(7), 1464.

ANTI-CANCER / ANTI-TUMOR

• In a review of 17 studies, it was concluded that intake of citrus fruits was associated with a 50% reduction of risk in cavity and pharyngeal cancer. From: Cirmi, S., Navarra, M., Woodside, J. V., & Cantwell, M. M. (2018). Citrus fruits intake and oral cancer risk: A systematic review and meta-analysis. Pharmacological research, 133, 187-194.
• Citrus oils of sweet orange, grapefruit, and lemon induced apoptosis of human leukemia cancer tumor cells and limonene, decanal, octanal and citral showed strong apoptotic activity.  From:  Hata, T., Sakaguchi, I., Mori, M., Ikeda, N., Kato, Y., Minamino, M., & Watabe, K. (2002). Induction of apoptosis by Citrus paradisi essential oil in human leukemic (HL-60) cells. In vivo (Athens, Greece), 17(6), 553-559.

ANTI-INFLAMMATORY

• In a summary of research, hesperidin is a bioflavonoid found in high concentrations in citrus fruit with a significant anti-inflammatory and antioxidant effect. From: Tejada, S., Pinya, S., Martorell, M., Capó, X., Tur, J. A., Pons, A., & Sureda, A. (2018). Potential anti-inflammatory effects of hesperidin from the genus Citrus. Current medicinal chemistry, 25(37), 4929-4945.
• In a summary of research, hesperidin is a bioflavonoid found in high concentrations in citrus fruit with a significant anti-inflammatory and antioxidant effect. From: Tejada, S., Pinya, S., Martorell, M., Capó, X., Tur, J. A., Pons, A., & Sureda, A. (2018). Potential anti-inflammatory effects of hesperidin from the genus Citrus. Current medicinal chemistry, 25(37), 4929-4945.

​SKIN

• In a study of 95 women, long term ingestion of a supplement containing rosemary and grapefruit extracts improved the visual signs of sun damage on the skin, including elasticity, wrinkles, and color.  From:  Nobile, V., Michelotti, A., Cestone, E., Caturla, N., Castillo, J., Benavente-García, O., … & Micol, V. (2016). Skin photoprotective and antiageing effects of a combination of rosemary (Rosmarinus officinalis) and grapefruit (Citrus paradisi) polyphenols. Food & nutrition research, 60(1), 31871.

ANXIOLYTIC

• A human study including grapefruit, rose, orange, lime, and lemon, with 200 participants in Germany, showed grapefruit aroma to reduce anxiety and improve attention in both men and women.  From:  Haehner, A., Maass, H., Croy, I., & Hummel, T. (2017). Influence of room fragrance on attention, anxiety and mood. Flavour and Fragrance Journal, 32(1), 24-28.
• The limonene constituent showed an anxiolytic effect in vivo.  From:  Lima, N. G., De Sousa, D. P., Pimenta, F. C. F., Alves, M. F., De Souza, F. S., Macedo, R. O., … & de Almeida, R. N. (2013). Anxiolytic-like activity and GC–MS analysis of (R)-(+)-limonene fragrance, a natural compound found in foods and plants. Pharmacology Biochemistry and Behavior, 103(3), 450-454.
• Limonene showed an anxiolytic effect in mice.  From:  de Almeida, A. A. C., de Carvalho, R. B. F., Silva, O. A., de Sousa, D. P., & de Freitas, R. M. (2014). Potential antioxidant and anxiolytic effects of (+)-limonene epoxide in mice after marble-burying test. Pharmacology Biochemistry and Behavior, 118, 69-78.
• Limonene affected brain neurotransmitter levels in rats.  From:  Zhou, W., Yoshioka, M., & Yokogoshi, H. (2009). Sub-chronic effects of s-limonene on brain neurotransmitter levels and behavior of rats. Journal of nutritional science and vitaminology, 55(4), 367-373.
• Grapefruit had an anti-anxiety effect on mice.  From:  Gupta, V., Bansal, P., Niazi, J., & Kaur, G. (2010). Anti-anxiety Activity of Citrus paradisi var. star ruby Extracts. International Journal of PharmTech Research, 2(3), 1655-1657.

STIMULANT / ANTIDEPRESSANT

• Fragrance inhalation affected the sympathetic nervous system. Pepper, estragon oil, fennel, and grapefruit increased sympathetic activity, and rose and patchouli oils decreased sympathetic activity.  Inhaling pepper oil increased plasma adrenaline levels while rose oil decreased adrenealine.  From:  Haze, S., Sakai, K., & Gozu, Y. (2002). Effects of fragrance inhalation on sympathetic activity in normal adults. The Japanese journal of pharmacology, 90(3), 247-253.
• Rats given an extract of the leaves of Citrus paradisi  var. Duncan had improved swimming activity. From: Gupta, V., Bansal, P., Kumar, P., & Shri, R. (2010). Anxiolytic and antidepressant activities of different extracts from Citrus paradisi var. duncan. Asian J Pharm Clin Res, 3(2), 98-100.
• Rats given an extract of the leaves of Citrus paradisi var. foster had improved swimming activity. From: Vikas, G., Parveen, B., Pawan, K., & Richa, S. (2009). Anxiolytic and antidepressant activities of different extracts from Citrus paradisi var. foster. Journal of Pharmacy Research, 2(12), 1864-1866.

COGNITION

• Juices from grapefruit and sweet orange improved cognitive performance and memory in mice. From: Mallick, N., Anjum, F., Ali, H., & Bano, N. (2018). MEMORY BOOSTING EFFECT OF CITRUS JUICES.

WEIGHTY LOSS / ANTI-CELLULITE

• In a twelve week randomized double blind trial of overweight men, intake of a polyphenol citrus extract had a slimming effect with improved muscle mass metabolism.From:  Cases, J., Romain, C., Dallas, C., Gerbi, A., & Rouanet, J. M. (2015). A 12-week randomized double-blind parallel pilot trial of Sinetrol XPur on body weight, abdominal fat, waist circumference, and muscle metabolism in overweight men. International journal of food sciences and nutrition, 66(4), 471-477.
• Results of the study showed grapefruit oil efficiently inhibits adipogenesis.  From:  Haze, S., Sakai, K., Gozu, Y., & Moriyama, M. (2010). Grapefruit oil attenuates adipogenesis in cultured subcutaneous adipocytes. Planta medica, 76(10), 950-955.
• A randomized placebo controlled study of 91 obese patients showed twelve week intake of grapefruit juice reduced glucose insulin levels and reduced weight.  From:  Fujioka, K., Greenway, F., Sheard, J., & Ying, Y. (2006). The effects of grapefruit on weight and insulin resistance: relationship to the metabolic syndrome. Journal of medicinal food, 9(1), 49-54.
• Exposure to the scent of grapefruit oil, and its component limonene, affected the autonomic nerves in rats, acting as a stimulant that enhanced lipolysis through a histaminergic response, and reduces appetite and body weight.  From:  Shen, J., Niijima, A., Tanida, M., Horii, Y., Maeda, K., & Nagai, K. (2005). Olfactory stimulation with scent of grapefruit oil affects autonomic nerves, lipolysis and appetite in rats. Neuroscience letters, 380(3), 289-294.
• In a review of research grapefruit and its component, naringin has shown antioxidant, lipid-lowering, antihypertensive, antidiabetic, cardiac protective, and anti-obesity effects. From: Razavi, B. M., & Hosseinzadeh, H. (2019). A Review of the Effects of Citrus paradisi (Grapefruit) and Its Flavonoids, Naringin, and Naringenin in Metabolic Syndrome. In Bioactive Food as Dietary Interventions for Diabetes (pp. 515-543). Academic Press.
• Olfactory stimulation of the aromas of grapefruit and lemon increased lipolysis and caused a suppression in body weight gain in rats. From: Niijima, A., & Nagai, K. (2003). Effect of olfactory stimulation with flavor of grapefruit oil and lemon oil on the activity of sympathetic branch in the white adipose tissue of the epididymis. Experimental Biology and Medicine, 228(10), 1190-1192.
• In rodents, grapefruit aroma and its limonene constituent affected brain activity to suppress appetite while lavender and its linalool constituent had the opposite effect. From: Nagai, K., Niijima, A., Horii, Y., Shen, J., & Tanida, M. (2014). Olfactory stimulatory with grapefruit and lavender oils change autonomic nerve activity and physiological function. Autonomic Neuroscience, 185, 29-35.

ANTI-DIABETIC

• A randomized placebo controlled study of 91 obese patients showed twelve week intake of grapefruit juice reduced glucose insulin levels and reduced weight.  From:  Fujioka, K., Greenway, F., Sheard, J., & Ying, Y. (2006). The effects of grapefruit on weight and insulin resistance: relationship to the metabolic syndrome. Journal of medicinal food, 9(1), 49-54.
• In a review of research, flavone glycosides (naringin, hesperidin, and diosmin) found in citrus fruit have an anti-diabetic effect. From: Srinivasan, S., Vinothkumar, V., & Murali, R. (2019). Antidiabetic Efficacy of Citrus Fruits With Special Allusion to Flavone Glycosides. In Bioactive Food as Dietary Interventions for Diabetes (pp. 335-346). Academic Press.
• Phenolic components from citrus fruits showed antioxidant, hypoglycemic, hypotensive activities in vitro.   From: Alu’Datt, M. H., Rababah, T., Alhamad, M. N., Al-Mahasneh, M. A., Ereifej, K., Al-Karaki, G., … & Ghozlan, K. A. (2017). Profiles of free and bound phenolics extracted from Citrus fruits and their roles in biological systems: content, and antioxidant, anti-diabetic and anti-hypertensive properties. Food & function, 8(9), 3187-3197.

HYPOLIPIDEMIC

• In a 16 week double blind study of 27 people with risk for coronary heart disease due to hypercholesterolemia, intake of  a grapefruit supplement reduced cholesterol levels.  From:  Cerda, J. J., Robbins, F. L., Burgin, C. W., Baumgartner, T. G., & Rice, R. W. (1988). The effects of grapefruit pectin on patients at risk for coronary heart disease without altering diet or lifestyle. Clinical cardiology, 11(9), 589-594.
• In a study of 57 hyperlipidemic patients that had coronary bypass surgery, a diet containing grapefruit positively affected serum lipid levels, especially triglycerides.  From:  From:  Gorinstein, S., Caspi, A., Libman, I., Lerner, H. T., Huang, D., Leontowicz, H., … & Trakhtenberg, S. (2006). Red grapefruit positively influences serum triglyceride level in patients suffering from coronary atherosclerosis: studies in vitro and in humans. Journal of agricultural and food chemistry, 54(5), 1887-1892.
• Orange and grapefruit reduced cholesterol in rats.  From:  Mallick, N., & Khan, R. A. (2016). Antihyperlipidemic effects of Citrus sinensis, Citrus paradisi, and their combinations. Journal of pharmacy & bioallied sciences, 8(2), 112.
• In a review of research grapefruit and its component, naringin has shown antioxidant, lipid-lowering, antihypertensive, antidiabetic, cardiac protective, and anti-obesity effects. From: Razavi, B. M., & Hosseinzadeh, H. (2019). A Review of the Effects of Citrus paradisi (Grapefruit) and Its Flavonoids, Naringin, and Naringenin in Metabolic Syndrome. In Bioactive Food as Dietary Interventions for Diabetes (pp. 515-543). Academic Press.
• Phenolic components from citrus fruits showed antioxidant, hypoglycemic, hypotensive activities in vitro.   From: Alu’Datt, M. H., Rababah, T., Alhamad, M. N., Al-Mahasneh, M. A., Ereifej, K., Al-Karaki, G., … & Ghozlan, K. A. (2017). Profiles of free and bound phenolics extracted from Citrus fruits and their roles in biological systems: content, and antioxidant, anti-diabetic and anti-hypertensive properties. Food & function, 8(9), 3187-3197.

INSECTICIDAL / LARVICIDAL / REPELLENT

• Citrus aurantium (bergamot) and Citrus paradisi (grapefruit) showed a good larvicidal effect against the malaria vector.  From:  Sedaghat, M. M., Sanei-Dehkordi, A., Vatandoost, H., & Abai, M. R. (2016). Chemical Compositions of the Peel Essential Oil of Citrus aurantium and its Natural Larvicidal Activity against the Malaria Vector Anopheles stephensi (Diptera: Culicidae) in Comparison with Citrus paradisi. Journal of Arthropod-Borne Diseases.
• Twenty children that used a shampoo containing grapefruit extract showed a reduction in head lice.  From:  Abdel-Ghaffar, F., Semmler, M., Al-Rasheid, K., Klimpel, S., & Mehlhorn, H. (2010). Efficacy of a grapefruit extract on head lice: a clinical trial. Parasitology research, 106(2), 445.
• These tested citrus essential oils are listed in order of repelling effectiveness against two mosquito species when applied to human skin: C. aurantifolia, C. microcarpa, C. maxima, C. reticulate, C. sinensis, C. hystrix, C. aurantium, and C. medica var sarcodaclylis. From: Soonwera, M. (2015). Efficacy of essential oils from Citrus plants against mosquito vectors Aedes aegypti (Linn.) and Culex quinquefasciatus (Say). Journal of Agricultural Technology, 11(3), 669-681.

COMMON COLD

• In a large double blind study, vitamin C reduced the duration and symptoms of the common cold.  From:  Anderson, T. W., Reid, D. B. W., & Beaton, G. H. (1972). Vitamin C and the common cold: a double-blind trial. Canadian Medical Association Journal, 107(6), 503.

ASTHMA / LUNG FUNCTION

• In a large review of over 4000 children showed eating citrus and kiwi reduced asthma and wheezing symptons.  From:  Forastiere, F., Pistelli, R., Sestini, P., Fortes, C., Renzoni, E., Rusconi, F., … & SIDRIA Collaborative Group. (2000). Consumption of fresh fruit rich in vitamin C and wheezing symptoms in children. Thorax, 55(4), 283-288.
• In a longitudinal study of over 2,000 British adults, eating citrus was associated with higher lung function.  From:  Carey, I. M., Strachan, D. P., & Cook, D. G. (1998). Effects of changes in fresh fruit consumption on ventilatory function in healthy British adults. American journal of respiratory and critical care medicine, 158(3), 728-733.

CHILDREN’S HEALTH

• Twenty children that used a shampoo containing grapefruit extract showed a reduction in head lice.  From:  Abdel-Ghaffar, F., Semmler, M., Al-Rasheid, K., Klimpel, S., & Mehlhorn, H. (2010). Efficacy of a grapefruit extract on head lice: a clinical trial. Parasitology research, 106(2), 445.
• In a large review of over 4000 children showed eating citrus and kiwi reduced asthma and wheezing symptons.  From:  Forastiere, F., Pistelli, R., Sestini, P., Fortes, C., Renzoni, E., Rusconi, F., … & SIDRIA Collaborative Group. (2000). Consumption of fresh fruit rich in vitamin C and wheezing symptoms in children. Thorax, 55(4), 283-288.

SPASMOLYTIC

• Carvone and limonene showed involuntary muscle spasmolytic activity in vitro. From: de Sousa, D. P., Mesquita, R. F., de Araújo Ribeiro, L. A., & de Lima, J. T. (2015). Spasmolytic activity of carvone and limonene enantiomers. Natural product communications, 10(11), 1934578X1501001120.

By: Kathy Sadowski

Updated: 9/12/19