Dr Paul Clayton 2006


Researchers in Athens set out to investigate chocolate’s heart health benefits by investigating the effect of eating dark chocolate on three determinants of cardio-vascular performance: endothelial function (the lining of blood vessels), arterial stiffness, and wave reflections(5).

All three are predictors of cardiovascular risk. Their study found that soon after eating dark chocolate, wave reflections and endothelial function were both improved – a combination considered to be significantly cardioprotective. Soon after, their colleagues at the University of California published almost identical results(6).

Lowers blood pressure

In a separate study carried out at the University of L’Aquila in Italy, cocoa was found to lower blood pressure in patients with essential hypertension(7). Somewhat to the surprise of the experimenters, it also improved insulin sensitivity – an effect which would make cocoa and cocoa products very well suited to diabetics!

Within 12 months, a group at the University of Buenos Aires showed that the anti-hypertensive effect of cocoa was due to its ability to inhibit ACE, the same enzyme targeted by many antihypertensive drugs(8). At our own University of Dundee, dark chocolate was shown to reduce blood platelet activity, a generally desirable effect which reduces the risks of both heart attacks and stroke(9). (Milk and white chocolate were ineffective.) The University of Kuopio in Finland found dark chocolate increased levels of HDL, the healthy form of cholesterol(10).

Finally, in January ’06, a team of scientists at the Harvard School of Public Health performed a meta-analysis of cocoa and chocolate studies and concluded that eating chocolate was indeed likely to reduce the risk of heart disease and stroke(11).


References

  1. Lee KW, Kim YJ, Lee HJ, Lee CY. Cocoa has more phenolic phytochemicals and a higher antioxidant capacity than teas and red wine. J Agric Food Chem. 2003 Dec 3;51(25):7292-5.
  2. Hammerstone JF, Lazarus SA, Mitchell AE, et al. Identification of procyanidins in cocoa (Theobroma Cacao) and chocolate using high-performance liquid chromatography/mass spectrometry. J Agric Food Chem. 1999; 47:490-496.
  3. Lazarus SA, Hammerstone JF, Schmitz HA. Chocolate contains additional flavonoids not found in tea. Lancet 1999; 354:1825.
  4. Vinson JA, Proch J, Zubik L. Phenol antioxidant quantity and quality in foods: cocoa, dark chocolate and milk chocolate. J Agric Food Chem. 1999; 47:4821-4824.
  5. Vlachopoulos C, Aznaouridis K, Alexopoulos N, Economou E, Andreadou I, Stefanadis C. Effect of dark chocolate on arterial function in healthy individuals. Am J Hypertens. 2005 Jun;18(6):785-91.
  6. Engler MB, Engler MM, Chen CY, Malloy MJ, Browne A, Chiu EY, Kwak HK, Milbury P, Paul SM, Blumberg J, Mietus-Snyder ML. Flavonoid-rich dark chocolate improves endothelial function and increases plasma epicatechin concentrations in healthy adults. J Am Coll Nutr. 2004 Jun;23(3):197-204.
  7. Grassi D, Necozione S, Lippi C, Croce G, Valeri L, Pasqualetti P, Desideri G, Blumberg JB, Ferri C. Cocoa reduces blood pressure and insulin resistance and improves endothelium-dependent vasodilation in hypertensives. Hypertension 2005 Aug;46(2):398-405.
  8. Actis-Goretta L, Ottaviani JI, Fraga CG. Inhibition of angiotensin converting enzyme activity by flavanol-rich foods. J Agric Food Chem. 2006 Jan 11;54(1):229-34.
  9. Innes AJ, Kennedy G, McLaren M, Bancroft AJ, Belch JJ. Dark chocolate inhibits platelet aggregation in healthy volunteers. Platelets 2003 Aug;14(5):325-7.
  10. Mursu J, Voutilainen S, Nurmi T, Rissanen TH, Virtanen JK, Kaikkonen J, Nyyssonen K, Salonen JT. Dark Chocolate Consumption Increases HDL Cholesterol Concentration and Chocolate Fatty Acids May Inhibit Lipid Peroxidation in Healthy Humans. Free Radic Biol Med. 2004 Nov 1;37(9):1351-9.
  11. Ding EL, Hutfless SM, Ding X, Girotra S. Chocolate and prevention of cardiovascular disease: a systematic review. Nutr Metab (Lond). 2006 Jan 3;3:2.
  12. Carnesecchi S, Schneider Y, Lazarus SA, Coehlo D, Gosse F, Raul F. Flavanols and procyanidins of cocoa and chocolate inhibit growth and polyamine biosynthesis of human colonic cancer cells. Cancer Lett. 2002 Jan 25;175(2):147-55.
  13. Noe V, Penuelas S, Lamuela-Raventos RM, Permanyer J, Ciudad CJ, Izquierdo-Pulido M. Epicatechin and a cocoa polyphenolic extract modulate gene expression in human Caco-2 cells. J Nutr. 2004 Oct;134(10):2509-16.
  14. Kenny TP, Keen CL, Jones P, Kung HJ, Schmitz HH, Gershwin ME. Pentameric procyanidins isolated from Theobroma cacao seeds selectively downregulate ErbB2 in human aortic endothelial cells. Exp Biol Med (Maywood). 2004 Mar;229(3):255-63.
  15. Kenny TP, Keen CL, Jones P, Kung HJ, Schmitz HH, Gershwin ME. Cocoa procyanidins inhibit proliferation and angiogenic signals in human dermal microvascular endothelial cells following stimulation by low-level H2O2. Exp Biol Med (Maywood). 2004 Sep;229(8):765-71.
  16. Kozikowski AP, Tuckmantel W, Bottcher G, Romanczyk LJ Jr. Studies in polyphenol chemistry and bioactivity. 4.(1) Synthesis of trimeric, tetrameric, pentameric, and higher oligomeric epicatechin-derived procyanidins having all-4beta,8-interflavan connectivity and their inhibition of cancer cell growth through cell cycle arrest. J Org Chem. 2003 Mar 7;68(5):1641-58.
  17. Ramljak D, Romanczyk LJ, Metheny-Barlow LJ, Thompson N, Knezevic V, Galperin M, Ramesh A, Dickson RB. Pentameric procyanidin from Theobroma cacao selectively inhibits growth of human breast cancer cells. Mol Cancer Ther. 2005 Apr;4(4):537- 46.
  18. Tavani A, Giordano L, Gallus S, Talamini R, Franceschi S, Giacosa A, Montella M, La Vecchia C. High glycemic foods linked to increased risk of breat cancer, via insulin and insulin growth factors. Ann Oncol. 2006 Feb;17(2):341-5.
  19. Mao TK, Powell J, Van de Water J, et al. The effect of cocoa procyanidins on the transcription and secretion of interleukin 1beta in peripheral blood mononuclear cells. Life Sci. 2000; 66:1377-1386.
  20. Mao TK, Powell JJ, Van de Water J, et al. The influence of cocoa procyanidins on the transcription of interleukin-2 in peripheral blood mononuclear cells. Int J Immunotherapy 1999; 15:23-29.
  21. N, Sakane T. Polyphenols in chocolate, which have antioxidant activity, modulate immune function in humans in vitro. Cell Immunol. 1997; 177:129-136.
  22. Hollenberg NK, Mohres E, Meinking T, Preston M, Crespo B, Rivera A, Jackson L, Martinez G, Loken WM. Stress and blood pressure in Kuna Amerinds. J Clin Hypertens (Greenwich). 2005 Dec;7(12):714-20.
  23. Hollenberg NK: Data presented at the 2006 Symposium on Cocoa, February 9-10, 2006 at The National Academies, Washington D.C.
  24. Buijsse B, Feskens EJ, Kok FJ, Kromhout D. Cocoa intake, blood pressure, and cardiovascular mortality: the Zutphen Elderly Study. Arch Intern Med. 2006 Feb 27;166(4):411-7.
  25. Fisher NDL and Hollenberg NK. Flavanols for cardiovascular health: The science behind the sweetness. Journal of Hypertension 2005 August;23:1453-1459.