INTRODUCTION: HERE IS A GRAPEFRUIT
If you are a devout follower of Paleo, then you know that we encourage eating fruits such as grapefruit. In addition to being low in calories, it is also a great source of vitamin C, as well as vitamin A, vitamin B5, and vitamin B9.1 Furthermore grapefruit is packed with fiber, and phytonutrients like lycopene, limonoids and flavanones.2
Over the years, many scientific studies have shown the great health benefits, including decreasing cancerous growth3, and possibly being as effective in treating diabetes type II as metformin.4 An exceptional study just published in the American Journal of Clinical Nutrition provides great evidence regarding the benefits of grapefruit consumption on vascular function in postmenopausal women and decreasing the risk of arterial stiffness.5 In simpler terms, how drinking grapefruits can boost the arteries, and decrease the risk of developing cardiovascular diseases such as a myocardial infarction/heart attack, or a stroke.
OVERVIEW OF STUDY
Researchers recruited 48 healthy postmenopausal women who were between three to 10 years post menopause. These women were randomly assigned to drink 340 mL of grapefruit juice a day containing 210 mg naringenin glycosides (flavanones), or a matched control drink without flavanones for 6 months each. Then there was a two month washout period between beverages, before the participants were crossed over into the other group.
The most important end-point was the measurement of endothelial function in the brachial artery by means of flow-mediated dilation. Additionally, blood pressure, arterial stiffness, and endothelial function in the peripheral arterial bed were assessed as signs of vascular function. These measurements and blood collection for clinical biochemical markers were carried out in overnight-fasted subjects, pre and post the six month treatment periods.
The results showed a significant decrease in the carotid-femoral pulse wave velocity (PWV) after the consumption of grapefruit juice, at 7.36 m/s. On the other hand, it was 7.70 m/s after consumption of the matched control drink without flavanones. This PWV is seen as the gold standard for evaluating central arterial stiffness, and has a strong correlation with the development of the risk of cardiovascular disease6. The scientists estimate that the PWV reduction of -0.524 m/s is similar to about an absolute 5% risk reduction in cardiovascular disease.
WHAT ARE FLAVANONES?
Many people may be unaware of flavanones. These are compounds that are a subclass of flavonoids, and seen mainly in citrus fruits such as oranges and grapefruits.7 While an orange has the highest amounts of flavanones at 48 mg/100 g aglycones,8 a grapefruit has a total flavanone content (summed means) of 27 mg/100 g9. Lemons contain an overall flavanone content of 26 mg aglycones/100 g edible fruit or juice, while limes have 17 mg aglycones/100 g edible fruit or juice.10 Epidemiological studies showed and demonstrated the many benefits of flavanones including its anti-inflammatory and lipid-lowering properties.11 A previous study demonstrated the possibility of flavanones decreasing the risk of ischemic stroke in women by 17%.12
Well you may be wondering since oranges have a greater content of flavanones, would it not be easier to just drink up some orange juice instead? Well as we have always advocated, commercial juices frequently contain excess sugar, and while you may benefit from the decreased risk of cardiovascular disease, it would be unwise to do so at the expense of diabetes.
ARTERIAL STIFFNESS
As one ages, the aorta stiffens, a process that may be hastened by arterial hypertension.13 It results in a condition known as arteriosclerosis.14 So, if you have high blood pressure, you really should be eating your grapefruits and oranges. Arterial stiffness describes the decreased ability of the artery to swell up and contract as a result of any pressure changes.15 In addition, multiple studies have also shown the predictive significance of arterial stiffness (AS) in a range of populations as an independent predictor of cardiovascular morbidity and all-cause mortality.16
CONCLUSION
In closing, this recent study suggests that the consumption of grapefruit juice by middle aged post-menopausal women is beneficial for arterial stiffness. Given the earlier statement about the possibility of increased sugar in juices, my suggestion instead would be to eat grapefruit whole instead, as we recommend with other fruit and vegetables when following a Paleo diet. Moreover, careful chewing has been shown to stimulate the release of 2 intestinal peptides which decrease appetite and food intake.17 This indicates more benefits for you to actually eat a grapefruit, instead of drinking the juice.
REFERENCES
[1] Consumption of Clarified Grapefruit Juice Ameliorates High-Fat Diet Induced Insulin Resistance and Weight Gain in Mice. PLoS ONE 9(10): e108408. doi:10.1371/journal.pone.0108408
[2] Consumption of Clarified Grapefruit Juice Ameliorates High-Fat Diet Induced Insulin Resistance and Weight Gain in Mice. PLoS ONE 9(10): e108408. doi:10.1371/journal.pone.0108408
[3] Consumption of Clarified Grapefruit Juice Ameliorates High-Fat Diet Induced Insulin Resistance and Weight Gain in Mice. PLoS ONE 9(10): e108408. doi:10.1371/journal.pone.0108408
[4] Chudnovskiy R, Thompson A, Tharp K, Hellerstein M, Napoli JL, Stahl A (2014) Consumption of Clarified Grapefruit Juice Ameliorates High-Fat Diet Induced Insulin Resistance and Weight Gain in Mice. PLoS ONE 9(10): e108408. doi:10.1371/journal.pone.0108408
[5] Habauzit V, Verny MA, Milenkovic D, Barber-Chamoux N, Mazur A, Dubray C, Morand C.Flavanones protect from arterial stiffness in postmenopausal women consuming grapefruit juice for 6 mo: a randomized, controlled, crossover trial. Am J Clin Nutr. 2015 Jul;102(1):66-74. doi: 10.3945/ajcn.114.104646
[6] Cavalcante JL, Lima JC, Redheuil A, Al-Mallah MH. Aortic Stiffness: Current Understanding and Future Directions. J Am Coll Cardiol. 2011;57(14):1511-1522. doi:10.1016/j.jacc.2010.12.017.
[7] Peterson, J., Beecher, G., Bhagwat, S., Dwyer, J., Gebhardt, S., Haytowitz, D., & Holden, J. (2006). Flavanones in grapefruit, lemons, and limes: A compilation and review of the data from the analytical literature. Journal of Food Composition and Analysis, 19, S74–S80.
[8] Peterson, J., Beecher, G., Bhagwat, S., Dwyer, J., Gebhardt, S., Haytowitz, D., & Holden, J. (2006). Flavanones in grapefruit, lemons, and limes: A compilation and review of the data from the analytical literature. Journal of Food Composition and Analysis, 19, S74–S80.
[9] Peterson, J., Beecher, G., Bhagwat, S., Dwyer, J., Gebhardt, S., Haytowitz, D., & Holden, J. (2006). Flavanones in grapefruit, lemons, and limes: A compilation and review of the data from the analytical literature. Journal of Food Composition and Analysis, 19, S74–S80.
[10] Peterson, J., Beecher, G., Bhagwat, S., Dwyer, J., Gebhardt, S., Haytowitz, D., & Holden, J. (2006). Flavanones in grapefruit, lemons, and limes: A compilation and review of the data from the analytical literature. Journal of Food Composition and Analysis, 19, S74–S80.
[11] Peterson, J., Beecher, G., Bhagwat, S., Dwyer, J., Gebhardt, S., Haytowitz, D., & Holden, J. (2006). Flavanones in grapefruit, lemons, and limes: A compilation and review of the data from the analytical literature. Journal of Food Composition and Analysis, 19, S74–S80.
[12] Cassidy, A., Rimm, E., O'Reilly, E., Logroscino, G., Kay, C., Chiuve, S., & Rexrode, K. (2012). Dietary Flavonoids and Risk of Stroke in Women. Stroke, 43, 946-951. doi:10.1161/STROKEAHA.111.637835
[13] Cavalcante JL, Lima JC, Redheuil A, Al-Mallah MH. Aortic Stiffness: Current Understanding and Future Directions. J Am Coll Cardiol. 2011;57(14):1511-1522. doi:10.1016/j.jacc.2010.12.017.
[14] Cavalcante JL, Lima JC, Redheuil A, Al-Mallah MH. Aortic Stiffness: Current Understanding and Future Directions. J Am Coll Cardiol. 2011;57(14):1511-1522. doi:10.1016/j.jacc.2010.12.017.
[15] Cavalcante JL, Lima JC, Redheuil A, Al-Mallah MH. Aortic Stiffness: Current Understanding and Future Directions. J Am Coll Cardiol. 2011;57(14):1511-1522. doi:10.1016/j.jacc.2010.12.017.
[16] Cavalcante JL, Lima JC, Redheuil A, Al-Mallah MH. Aortic Stiffness: Current Understanding and Future Directions. J Am Coll Cardiol. 2011;57(14):1511-1522. doi:10.1016/j.jacc.2010.12.017.
[17] Keller, D. (2011, September 13). Thorough Chewing Raises Hormones Regulating Food Intake. Retrieved July 9, 2015, from Medscape: //www.medscape.com/viewarticle/749504
