Blood Pressure Is Reduced and Insulin Sensitivity Increased in Glucose-Intolerant, Hypertensive Subjects after 15 Days of Consuming High-Polyphenol Dark Chocolate13
Open accessAbstract
Flavanols from chocolate appear to increase nitric oxide bioavailability, protect vascular endothelium, and decrease cardiovascular disease (CVD) risk factors. We sought to test the effect of flavanol-rich dark chocolate (FRDC) on endothelial function, insulin sensitivity, beta-cell function, and blood pressure (BP) in hypertensive patients with impaired glucose tolerance (IGT). After a run-in phase, 19 hypertensives with IGT (11 males, 8 females; 44.8 +/- 8.0 y) were randomized to receive isocalorically either FRDC or flavanol-free white chocolate (FFWC) at 100 g/d for 15 d. After a wash-out period, patients were switched to the other treatment. Clinical and 24-h ambulatory BP was determined by sphygmometry and oscillometry, respectively, flow-mediated dilation (FMD), oral glucose tolerance test, serum cholesterol and C-reactive protein, and plasma homocysteine were evaluated after each treatment phase. FRDC but not FFWC ingestion decreased insulin resistance (homeostasis model assessment of insulin resistance; P < 0.0001) and increased insulin sensitivity (quantitative insulin sensitivity check index, insulin sensitivity index (ISI), ISI(0); P < 0.05) and beta-cell function (corrected insulin response CIR(120); P = 0.035). Systolic (S) and diastolic (D) BP decreased (P < 0.0001) after FRDC (SBP, -3.82 +/- 2.40 mm Hg; DBP, -3.92 +/- 1.98 mm Hg; 24-h SBP, -4.52 +/- 3.94 mm Hg; 24-h DBP, -4.17 +/- 3.29 mm Hg) but not after FFWC. Further, FRDC increased FMD (P < 0.0001) and decreased total cholesterol (-6.5%; P < 0.0001), and LDL cholesterol (-7.5%; P < 0.0001). Changes in insulin sensitivity (Delta ISI - Delta FMD: r = 0.510, P = 0.001; Delta QUICKI - Delta FMD: r = 0.502, P = 0.001) and beta-cell function (Delta CIR(120) - Delta FMD: r = 0.400, P = 0.012) were directly correlated with increases in FMD and inversely correlated with decreases in BP (Delta ISI - Delta 24-h SBP: r = -0.368, P = 0.022; Delta ISI - Delta 24-h DBP r = -0.384, P = 0.017). Thus, FRDC ameliorated insulin sensitivity and beta-cell function, decreased BP, and increased FMD in IGT hypertensive patients. These findings suggest flavanol-rich, low-energy cocoa food products may have a positive impact on CVD risk factors.
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Dietary flavanol consumption has been shown to reduce blood pressure and improve insulin sensitivity.
“In this regard, dietary flavanol consumption has been shown to reduce blood pressure and improve insulin sensitivity, 17,18 as well as to induce vasodilation of the peripheral 17,18 and cerebral vascular system, 19 increasing brain blood flow and perfusion.19,20”
Dietary flavanol consumption induces vasodilation of the peripheral and cerebral vascular system and increases brain blood flow and perfusion.
“In this regard, dietary flavanol consumption has been shown to reduce blood pressure and improve insulin sensitivity, 17,18 as well as to induce vasodilation of the peripheral 17,18 and cerebral vascular system, 19 increasing brain blood flow and perfusion.19,20”
Flavonoids improve nitric oxide bioavailability in the vasculature, which in turn plays a pivotal role in modulating cerebrovascular tone.
“In this regard, although we did not specifically evaluate the effect of cocoa flavanols on endothelial function, a number of studies, some also from our group, clearly demonstrated the ability of flavonoids to improve NO bioavailability in vasculature, 17,18,25 which, in turn, plays a pivotal role in modulating cerebrovascular tone.28”
The blood pressure reductions are consistent with previous findings in normotensive, hypertensive, and medicated individuals.
“The current demonstration of significant reductions in both systolic and diastolic blood pressure levels after regular cocoa flavanol consumption is consistent with previous findings obtained both in normotensives and in hypertensive subjects, as well as medicated individuals.17,18,29,30”
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- Authors
- Grassi, D., Desideri, G., Necozione, S., Lippi, C., Casale, R., Properzi, G., Blumberg, J. B., & Ferri, C.
- Affiliations
- University of L'Aquila (IT)
- Tufts University (US)
- Corresponding author
- Grassi, Davide
- Venue
- The Journal of Nutrition
- Publisher
- Elsevier BV
- Published
- 2008-09
- Volume
- 138
- Issue
- 9
- Pages
- 1671-1676
- ISSN
- 0022-3166 (ISSN-L)
- OpenAlex
- W2162222948
- Cited by
- 481
- References
- 45
- Citations by year
- 2026: 6 · 2025: 13 · 2024: 15 · 2023: 12 · 2022: 18 · 2021: 16 · 2020: 21 · 2019: 33 · 2018: 39 · 2017: 30 · 2016: 36 · 2015: 46 · 2014: 29 · 2013: 40 · 2012: 55
- FWCI
- 14.32
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Licence
- Locations
- Journal of Nutrition (publishedVersion)
- PubMed (publishedVersion)
- IRIS Research product catalog (Sapienza University of Rome) (submittedVersion)
- Archivio Istituzionale della Ricerca - Università degli Studi dell Aquila (submittedVersion)
- Funders
- U.S. Department of Agriculture (58‐1950‐4‐401)
- Agricultural Research Service (58-1950-4-401)
- Topics
- Health Sciences › Medicine › Biochemistry › Phytochemicals and Antioxidant Activities
- Health Sciences › Medicine › Physiology › Nitric Oxide and Endothelin Effects
- Life Sciences › Agricultural and Biological Sciences › Food Science › Food Chemistry and Fat Analysis
- Keywords
- dark chocolate, flavan-3-ols, polyphenols, hypertension, impaired glucose tolerance, insulin sensitivity, insulin resistance, beta-cell function, endothelial function, flow-mediated dilation, blood pressure reduction, white chocolate, dietary intervention, cardiovascular risk factors, LDL cholesterol, C-reactive protein, homocysteine, nitric oxide bioavailability, QUICKI, HOMA-IR, 24-hour ambulatory blood pressure, dietary fiber, dietary fat, dietary protein
- MeSH terms
- Adult, Blood Pressure, Cacao, Female, Flavonoids, Glucose Tolerance Test, Humans, Hypertension, Insulin Resistance, Male, Middle Aged, Phenols, Cross-Over Studies, Polyphenols
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