Eating dark chocolate may help improve energy levels, raise exercise stamina and improve other measures of heart health in sedentary older adults, according to a double blind placebo controlled study presented at the American College of Cardiology (ACC) Scientific Sessions 2015.
Researchers analyzed blood samples, exercise endurance tests and skeletal muscle biopsies from 17 volunteers before and after a 3-month period in which they were randomly assigned to eat a small amount of dark chocolate or placebo daily.
“This is the first study we have conducted with a normal sedentary population. We saw on average a 15% improvement in performance,” lead study author Pam Taub, MD, who is an assistant professor of medicine at the University of California, San Diego Health System, said.
“The findings were not surprising as we have showed in our animal studies that epicatechin, the compound in dark chocolate, improved exercise capacity and mitochondrial function. We also showed in a proof-of-concept study in patients with heart failure and diabetes that mitochondrial structure improved.”
Subjects given dark chocolate showed improvements in HDL cholesterol levels, a trend for decreases in triglycerides and increased proteins associated with metabolism and energy production. Exercise testing indicated the volunteers also had a higher capacity for exercise and more efficient energy production in their muscle cells.
For this investigation, 17 sedentary subjects (mean age, 50 years) were randomly assigned to consume two squares of Hershey’s Extra Dark Chocolate or placebo (20 grams) for 3 months. The volunteers in this study underwent bicycle ergometry to assess VO2 max and power. A lipid profile also was performed along with a skeletal muscle biopsy to investigate underlying biochemical mechanisms.
The researchers found a trend for an increase in VO2 max in the dark chocolate group and an increase in maximum work (watts) achieved compared with the placebo group. The dark chocolate group also showed significant increases in protein levels for metabolic and/or mitochondrial biogenesis control enzymes (PGC1-alpha, AMPK and LKB1) and in their phosphorylation levels.
It is believed that dark chocolate has a direct effect on blood pressure (BP), lipids, insulin resistance and inflammatory markers. The researchers report that the mechanism underlying these improvements is thought to be due to increased nitric oxide levels and improved endothelial function.
Dr. Taub said endocrinologists in particular may find these study results clinically significant because sedentary older adults with diabetes may benefit from daily dark chocolate consumption.
“Consumption of small amounts of dark chocolate that contains epicatechin improves mitochondrial function. Normal mitochondrial function is essential for all cellular metabolic processes and is important in patients with diabetes and metabolic syndrome. Prior studies have shown that dark chocolate is beneficial in diabetics and improves endothelial function,” Dr. Taub told Endocrinology Advisor.
She also said the results suggest dark chocolate could be an inexpensive and beneficial treatment for older adults who are unable to exercise due to disabilities or mobility limitations. Kim Williams, MD, who is the President of the ACC and the chief of cardiology at Rush University School of Medicine in Chicago, said these findings are intriguing and if validated in larger trials suggest that chocolate could help combat cardiovascular disease (CVD).
“This study was very small and so larger trials are needed,” said Dr. Williams in an interview with Endocrinology Advisor. “It may be that there is an opiate affect from chocolate and that may affect how people view exercise, but anything that helps with being less sedentary and more active is awesome.”
He said if eating chocolate can help motivate sedentary adults to move more then it could have a significant impact on heart health. Dr. Williams noted, however, that calories can be a concern, as eating large amounts of chocolate products could lead to significant weight gain.
- Taub PR et al. Abstract 1178-123. Presented at: American College of Cardiology (ACC) 64th Scientific Session & Expo; March 14-16, 2015; San Diego.