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Phytonutrients

Phytonutrients are plant compounds thought to have health-promoting qualities.

Phytonutrients are plant compounds which are thought to have health-promoting qualities. Scientists are discovering that these plant-derived components are intimately involved in fighting cellular damage, a common initiation step in the pathways for cancer, ageing, and a variety of diseases. 

Grapefruit and 100% grapefruit juice have an array of phytonutrients including carotenoids and flavonoids. 

Carotenoids

  • The red, orange, and yellow pigments in citrus are called carotenoids. Grapefruit has many carotenoids, especially in pink grapefruit and pink grapefruit juices, but the most concentrated are beta-carotene, lycopene, lutein, and zeaxanthin.1
  • Beta-carotene can be converted to vitamin A in the body, which is required for reproduction and growth, immune function, and maintaining healthy vision.2,3
  • Pink grapefruit and 100% pink grapefruit juice have lycopene, the same carotenoid that makes tomatoes red. Test tube studies show lycopene has one of the highest antioxidant activities of the carotenoids.4 Although studies report mixed results, lycopene may have beneficial effects towards lowering the risk of some cancers, including prostate and lung cancer.4
  • Carotenoids have antioxidant traits, help our cells communicate with each other, support our immune system, and some studies show they contain properties that protect against certain types of chronic diseases.3

The amount of carotenoids in food can vary widely depending on citrus variety, growing conditions, fruit maturity, processing, storage, and multiple other factors. 

Only pink grapefruit and pink grapefruit juices contribute to vitamin A intake. The amount of vitamin A delivered by carotenoids in half a pink grapefruit and 250 ml of 100% pink grapefruit juice is approximately 2-4% of the recommended Daily Value.*

Flavonoids

  • Grapefruit naturally includes many flavonoids, a class of plant compounds similar to those found in red wine (resveratrol), green tea (catechins), and cocoa (flavanols).
  • Naringenin is the most common flavonoid found in grapefruit, followed by hesperidin.5
  • Several flavonoids have been reported to have antioxidant, anti-inflammatory, and cardioprotective properties which may help protect against various diseases and conditions.6-11
  • In a randomized controlled study in healthy post-menopausal women, 100% grapefruit juice consumption was associated with beneficial effects on arterial stiffness.12 Arterial stiffness increases with ageing and has been associated with an increased risk of cardiovascular disease, including heart attack and stroke. The effects seen in this study were thought to be primarily due to naringenin.
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References

  1. USDA National Nutrient Database for Standard Reference, Release 28 (slightly revised).US Department of Agriculture, Agricultural Research Service, Nutrient Data Laboratory; May 2016. https://ndb.nal.usda.gov/ndb
  2. Carotenoids, in:Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids.Institute of Medicine.The National Academies Press, Washington, D.C.2000.
  3. Vitamin A, in:Dietary Reference Intakes.Institute of Medicine.The National Academies Press, Washington, D.C.2006.
  4. Linus Pauling Micronutrient Information Center.Oregon State University. http://lpi.oregonstate.edu/mic/dietary-factors/phytochemicals/carotenoids
  5. Bhagwat, Haytowitz.USDA Database for the Flavonoid Content of Selected Foods Release 3.2.In.Beltsville, MD:United States Department of Agriculture; 2015.
  6. Rangel-Huerta et al. J Nutr.2015;145(8):1808-1816.
  7. Milenkovic et al. PLoS One.2011;6(11):e26669.
  8. Morand et al. Am J Clin Nutr.2011;93:73–80.
  9. Rendeiro et al. Br J Nutr.2017;116(12):1999-2010.
  10. Napoleone et al.Thrombosis Research.2013;132(2):288-292.
  11. Gorinstein et al. J Agric Food Chem. 2004;52(16):5215-5222.
  12. Habauzit et al.Am J Clin Nutr.2015;102:66-74.