Several nutrients in chocolate affect heart rate, but the type of chocolate that has shown the most benefit to heart health is dark chocolate with cocoa content of 70 percent or more, according to "Today's Dietitian." Even with dark chocolate, however, it's important to consume chocolate in moderation, since despite the positive nutrients, chocolate still also is rich in calories, sugar and saturated fat.
Endothelial Function and Heart Rate
Endothelial function refers to the activities that occur at the lining or the walls of the blood vessels. The walls of blood vessels, or endothelium, are made to withstand the flow and pressure of blood. The integrity of the endothelium is critical to maintain because if it is compromised, heart rate increases because the heart has to pump harder to pump the blood through the entire body. Flavonoids found in chocolate produce nitric oxide, explains a study in the January 2006 journal "Nutrition and Metabolism." Nitric oxide functions to destroy and remove remnants from cell turnover and blood vessel injury. Without nitric oxide, these leftover remnants could accumulate and cause a blockage or a clot restricting blood flow and increasing heart rate.
Blood Pressure and Heart Rate
Nutrients in chocolate assist with lowering blood pressure, which results in decreasing heart rate. The effect chocolate has on blood pressure is similar to that of anti-hypertensive drugs. This is because the flavonoids in chocolate help to reduce angiotensin-converting enzyme, or ACE. Without this enzyme, angiotensin II cannot be created. Angiotensin II constricts blood vessels, which increases blood pressure. A study in the January 2011 "Journal of Cardiovascular Pharmacology" found significant reductions in ACE caused blood vessels to relax in participants who consumed 72 percent cocoa dark chocolate.
Platelet Function and Heart Rate
Heart rate is decreased by affecting platelet function and components in chocolate have been found to affect platelets. Platelets are very sticky, colorless components that flow through the bloodstream right next to the blood vessel walls. Platelets stick close to the walls because they are the first line of defense in response to cell or blood vessel injury as they try to clot the injury. The problem is that blood clots can build up, attach to blood vessel walls, tear off and travel through the bloodstream and adhere to another area in the blood vessel walls. All of this action obstructs blood flow and causes the heart to beat faster and harder. Antioxidants in chocolate known as catechin and epicatechin prevent platelets from sticking together and adhering, according to a study in the 2009 "Circulation" journal.
Inflammation and Heart Rate
Cocoa flavonoids in chocolate help to reduce inflammation in the bloodstream, allowing the blood to flow easier and decreasing heart rate. Cocoa flavonoids do this by affecting the lipooxygenase pathway. This pathway produces inflammatory substances known as leukotrienes. If the pathway is reduced or inhibited, the leukotrienes are not generated. Cytokines are another type of inflammatory protein that cocoa flavonoids inhibit in the blood vessels, explains the journal "Nutrition and Metabolism."
References
- Today's Dietitian: Chocolate and Nut Lovers Take Heart - Foods May Be Cardioprotective
- "Nutrition and Metabolism"; Chocolate and Prevention of Cardiovascular Disease: A Systematic Review; Eric L. Ding, et al.; Jan. 3, 2006
- "Journal of Cardiovascular Pharmacology"; Effects of Cocoa Extract and Dark Chocolate on Angiotensin-converting Enzyme and Nitric Oxide in Human Endothelial Cells and Healthy Volunteers--A Nutrigenomics Perspective; Ingrid Persson, et al.;January 2011
- "Circulation"; Cocoa and Cardiovascular Health; Roberto Corti, M.D., et. al.; 2009
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