One way to tell how healthy you are is by your pulse rate. For instance, the hearts of Olympic athletes like Michael Phelps are able to pump double the amount of blood each minute that the heart of an average adult male can. Although most people aren't able to train as hard as an Olympic athlete, changes you make to your diet can also have an effect on your pulse rate. The evidence for dark chocolate's benefits is inconclusive, but with many other heart-healthy properties, adding dark chocolate to your diet can be a champion idea.
Identification
Each time your heart expands and contracts, it pushes blood through your arteries, veins and capillaries, and you can feel these pulses at points on your body such as your neck or wrist. A normal pulse rate averages between 60 to 90 beats at rest and can range up to 200 during vigorous exercise. If your pulse rate drops too low, it's called brachycardia, and can cause dizziness or fainting. If your pulse is too high, known as tachycardia, it can signal an underlying medical problem, including heart disease.
Elevated Pulse Rate
Research published in "The American Journal of Clinical Nutrition" in 2008 set out to examine the short-term effects of dark chocolate and cocoa on heart health and mental functioning. The 101 subjects were assigned over a six-week period to receive either a daily 37 g dark chocolate bar, 8 oz of an artificially sweetened cocoa drink or a placebo. The scientists found that consumption of dark chocolate and cocoa was associated with significantly higher pulse rates than at baseline at three-week and six-week assessments.
Decreased Pulse Rate
A research team in Tokyo tested cacao liquor, pure chocolate in its liquid form, on rabbits with high cholesterol over a period of six months. When the study was published in "Basic Clinical Pharmacology and Toxicology" in 2008, it demonstrated that the chocolate extracts significantly reduced plaque buildup in the aortas of the rabbits and also lowered both blood pressure and heart rate.
No Effect
A study in the United Kingdom followed 16 healthy young subjects who ingested 150 mg of cocoa over five days. The study, published in 2006 in the "Journal of Cardiovascular Pharmacology," was primarily interested in the effects of the cocoa on the subjects' cognitive abilities, but the researchers also found that the moderate amounts of cocoa in the young people had no effect on pulse rate. A university hospital in Germany set out to study the effects of cocoa on blood vessel functioning in diabetic patients on medication. The findings were published in the June 2008 issue of the "Journal of the American College of Cardiology" and showed that a 30-day regimen of dietary cocoa helped reverse vascular dysfunction, although it didn't have an effect on pulse rate.
Considerations
Most studies have linked consumption of dark chocolate to lower blood pressure and cholesterol levels, improved blood vessel health and also the prevention of diabetes. However, if you already have high blood pressure, check with your doctor before consuming large amounts of chocolate. For maximum health benefits, choose varieties that have a cocoa content of at least 65 percent, or opt for natural cocoa powder, which provides the same benefits with fewer calories.
References
- Cleveland Clinic: Your Pulse and Your Target Heart Rate
- "American Journal of Clinical Nutrition"; A Double-Blind, Placebo-Controlled, Randomized Trial of the Effects of Dark Chocolate and Cocoa on Variables Associated with Neuropsychological Functioning and Cardiovascular Health; W David Crews, Jr, et al.; April 2008
- "Basic and Clinical Pharmicology and Toxicology"; Effects of Cacao Liquor Polyphenols on Cardiovascular and Autonomic Nervous Functions in Hypercholesterolaemic Rabbits; M. Akita; December 2008
- "Journal of Cardiovascular Pharmacology"; The Effect of Flavanol-Rich Cocoa on The fMRI Response to a Cognitive Task in Healthy Young People; S.T. Francis; 2006
- "Journal of the American College of Cardiology"; Sustained Benefits on Vascular Function Through Flavanol-Containing Cocoa on Medicated Diabetic Patients; J. Balzer; June 2008
