There’s a good reason why smart people choose chocolate bars that contain toasted almonds in them. It’s more than a matter of good taste. It’s a matter of good health. Daily indulgences like these may soon be viewed as an important medication to prevent high blood pressure.
Let me back up a few years and tell this story from the start.
Go back about 500 years ago to the days of the Spanish conquistadors. That was the time the Kuna Indians found refuge on a group of islands off the Caribbean Coast of Panama. The islands are rocky, dry, relatively mosquito free and most important at that time, surrounded by a barrier reef making them inaccessible to Spanish Galleons. Fast-forward half a millennium, to 1944; BH Keen reported to the medical world that the Kuna have strikingly no age related increase in hypertension. This was striking news as it is assumed that blood pressure as people age; this is a fact of life. Or at least that’s what everyone thought.
It was assumed that this absence of hypertension was some kind genetic fluke resulting from hundreds of years of inbreeding. It isn’t. The Kuna who move off the islands to Panama City rapidly lose their protection. City dwelling Kuna quickly develop hypertension; 45% of those over 60 have elevated blood pressure.
In 2006 Marjorie McCullough and her colleagues at Harvard completed a survey of the eating habits of the Kuna. McCullough’s data told us that while unsurprisingly the island dwelling Kuna eat more fish than their city dwelling member, the most striking difference in their diets was chocolate. The only liquid Island Kuna drink is a chocolate beverage. No coffee, tea, water or soda, just chocolate. The island dwelling Kuna consume a 10-fold higher amount of cocoa-containing beverages, than the urban Kuna.
At this point the Mars candy company offered funding and lab expertise to the Harvard researchers to figure out what was going on. They found that the chocolate these Kuna were imbibing so freely, because it was minimally processed, contains very high amounts of flavanoids, particularly the flavanols (-)epicatechin, (+)catechin and oligomers called procyanidins.
Astute readers will recognize these names. Certain types of epicatechins are found in green tea while we usually associate procyanidins with grape seed extracts. Once the Harvard scientists realized the key was chocolate they found research published a half dozen years earlier that helped them make sense of the Kuna phenomenon. Researchers from University of California, Davis had observed that cocoa flavanols can induce synthesis of prostacyclin and trigger relaxation of the heart’s aortic ring.
Further experiments have explained these mechanisms in greater detail. The current understanding is that flavanol rich cocoa triggers synthesis of nitric-oxide in the blood vessels. Nitric oxide causes the blood vessels to relax and dilate, lowering blood pressure.
This blood pressure lowering action of flavanol rich chocolates has been confirmed in numerous clinical trials over the last few years. A March 2010 study by Stefan Desch et al. published in the American Journal of Hypertension describes an experiment in which 102 patients with high blood pressure, severe enough to already have caused end organ damage, ate either 6 or 25 gram a day of a flavanol-rich dark chocolate for 3 months. The average blood pressures of both groups dropped. The larger 25 gram ‘dose’ of chocolate was not any more effective though than the 6 gram dose. It didn’t take much chocolate to make a difference considering that 6 grams is only about one quarter of an ounce. The same authors had, a few months earlier completed a meta-analysis of earlier chocolate hypertension studies, analyzing data from ten trials with a total 294 people. In their analysis, chocolate decreased systolic blood pressure an average of -4.5 mm Hg and diastolic by -2.5 mm Hg.
Admittedly, these aren’t large decreases but extrapolate them over a large population and they will lower morbidity and mortality a significant amount. Lowering blood pressure isn’t the only heart protective effect of chocolate. The flavanols in chocolate decrease vascular inflammation. In a November 2009 paper by Monagas et al., Spanish researchers tell us that a daily dose of chocolate milk decreased numerous blood markers of vascular inflammation. A paper from 2008, tells us that a eating a daily dose of chocolate providing 700 mg of flavanols for a month caused impressive changes in blood lipids in study participants. After just one week, low-density lipoprotein fell by 6% and high-density lipoprotein rose by 9%. Eating chocolate also reduced highly sensitive c-reactive protein levels in women. The real benefit of eating chocolate over the long term will be lower rates of cardiovascular disease. Oh, but I’ve gotten distracted with all this science stuff. What about the nuts? Nuts are an excellent source of an amino acid called l-arginine. Ask anyone with herpes; l-arginine seems to trigger herpes outbreaks. L-arginine has another claim to fame. It is the raw amino acid from which nitric oxide is synthesized. If one is deficient in l-arginine, once can’t make nitric oxide. Thus this amino acid is often prescribed as a supplement in the hope it will increase nitric oxide and increase blood flow in a range of conditions, ranging from angina to erectile dysfunction. Eating nuts with chocolate may have a synergistic effect at producing nitric oxide.
Before you run down to the grocery store and buy every chocolate bar in sight, there is some bad news about this whole business. The chocolates the Kuna eat and also the chocolate used in all these clinical trials isn’t the same sort of chocolate we can purchase at the store. The heat typically used in manufacturing chocolate destroys the flavanol chemicals it initially contained. Chocolate works for the Kuna because they make it themselves from the beans. The chocolate used in all these research studies was especially made using patented proprietary technology. Reading the small print in the recent studies and you will notice that either the Mars Candy Company (CirKuhealth) or Barry Callebaut, a manufacturer of Belgium chocolate (Acticoa) supplied the participants. Several other companies claim to have figured out how to make these special chocolates. Unfortunately it appears that Mars is bringing them to court for patent infringement. So for the moment hold off stuffing yourself with chocolate. In the next few months, these high flavanol chocolates may start appearing in retail outlets. Our goal is to get 500 to 700 mg of flavanols per day. If the label doesn’t specify flavanol content assume there are just a few milligrams in the product; you can’t use ‘good health’ to justify eating it. But soon, you may be able to……
Hollenberg NK, Martinez G, McCullough M, Meinking T, Passan D, Preston M, et al. Aging, acculturation, salt intake, and hypertension in the Kuna of Panama. Hypertension. 1997 Jan;29(1 Pt 2):171-6.
McCullough ML, Chevaux K, Jackson L, Preston M, Martinez G, Schmitz HH, Coletti C, Campos H, Hollenberg NK. Hypertension, the Kuna, and the epidemiology of flavanols. J Cardiovasc Pharmacol. 2006;47 Suppl 2:S103-9; discussion 119-21.
Schramm DD, Wang JF, Holt RR, Ensunsa JL, Gonsalves JL, Lazarus SA, Schmitz HH, German JB, Keen CL. Chocolate procyanidins decrease the leukotriene-prostacyclin ratio in humans and human aortic endothelial cells. Am J Clin Nutr. 2001 Jan;73(1):36-40.
Desch S, Kobler D, Schmidt J, Sonnabend M, Adams V, Sareban M, Eitel I, Blüher M, Schuler G, Thiele H. Low vs. Higher-Dose Dark Chocolate and Blood Pressure in Cardiovascular High-Risk Patients. Am J Hypertens. 2010 Mar 4.
Desch S, Schmidt J, Kobler D, Sonnabend M, Eitel I, Sareban M, Rahimi K, Schuler G, Thiele H. Am J Hypertens. Effect of cocoa products on blood pressure: systematic review and meta-analysis. 2010 Jan;23(1):97-103.
Monagas M, Khan N, Andres-Lacueva C, Casas R, Urpí-Sardà M, Llorach R, Lamuela-Raventós RM, Estruch R. Effect of cocoa powder on the modulation of inflammatory biomarkers in patients at high risk of cardiovascular disease. Am J Clin Nutr. 2009 Nov;90(5):1144-50.
Hamed MS, Gambert S, Bliden KP, Bailon O, Singla A, Antonino MJ, Hamed F, Tantry US, Gurbel PA. Dark chocolate effect on platelet activity, C-reactive protein and lipid profile: a pilot study. South Med J. 2008 Dec;101(12):1203-8.