Regular Dark Chocolate Consumption’s Reduction of Oxidative Stress and Increase of Free-Fatty-Acid Mobilization in Response to Prolonged Cycling

Abstract

This study investigated the effects of regular consumption of dark chocolate (DC), rich in cocoa polyphenols, on plasma metabolites, hormones, and markers of oxidative stress after prolonged exhaustive exercise. Twenty active men cycled at 60% maximal oxygen uptake (VO2max) for 1.5 hr, with the intensity increased to 90% VO2max for a 30-s period every 10 min, followed by a ride to exhaustion at 90% VO2max. In the 2 wk before exercise participants consumed 40 g of DC or an isocarbohydrate-fat control cocoa liquor–free chocolate (CON) twice daily and once 2 hr before exercise in a randomized, counterbalanced, crossover design. Venous blood samples were taken immediately before exercise, postexercise (fixed duration), postexhaustion, and after 1 hr of recovery. F2-isoprostanes were significantly lower (post hoc tests: p < .001) at exhaustion and after 1 hr of recovery with DC. Oxidized low-density lipoproteins were significantly lower with DC (p < .001) both before and after exercise and at exhaustion. DC was also associated with ~21% greater rises in free fatty acids during exercise (main effect: p < .05). Changes in circulating glucose, insulin, glucagon, cortisol, and interleukin (IL)-6, IL-10, and IL-1ra were unaffected by treatment. Time to exhaustion at 90% VO2max was not significantly different between trials (398 ± 204 and 374 ± 194 s for DC and CON, respectively). These results suggest that regular DC intake is associated with reduced oxidative-stress markers and increased mobilization of free fatty acids after exercise but has no observed effect on exercise performance.

The effect of acute dark chocolate consumption on carbohydrate metabolism and performance during rest and exercise

“…Despite differences in plasma glucose between treatments all measured glucose responses were euglycemic (>4 mmol), and thus it may not be surprising that the current study found no differences in ~11.5 min TT performance, which is consistent with a recent publication showing no change in a time to exhaustion performance test over ~6.5 min after chronic and acute dark chocolate consumption (Allgrove, Farrell et al 2011). Consequently, perhaps a more taxing and prolonged exercise stimulus may have altered the performance outcomes.…”

“…However, very few studies have examined metabolic and anti-fatigue effects of dark chocolate. Recent studies have shown that 100 g of dark chocolate increased the concentration of plasma glucose (Davison et al 2011), and chronic dark chocolate consumption caused a ~21% increase in plasma free-fatty acids (Allgrove et al 2011), during prolonged exercise compared to a iso-fat/calorie/carbohydrate (CHO) control. But, these studies did not examine mechanisms associated with these shifts in metabolism during exercise, nor performance outcomes.…”

“…However, whether acute DC consumption as found within this study directly has an LPL inhibitory effect remains to be determined. The recent studies by Allgrove et al (Allgrove, Farrell et al 2011) and Davison et al (Davison, Callister et al 2011) both showed significant increases in plasma FFA throughout moderate intensity exercise that were greater after dark chocolate consumption than control. In contrast, the current study found no differences in FFA concentrations during rest or exercise between groups.…”

The Effects of Dark Chocolate Consumption on Lipid Profile, Fasting Blood Sugar, Liver Enzymes, Inflammation, and Antioxidant Status in Patients with Non-Alcoholic Fatty Liver Disease: A Randomized, Placebo-Controlled, Pilot study

“…Latter studies have mostly supported a protective relationshipe between cocoa or chocolate consumption and a variety of health indicators [14] . The results of these studies have shown that cocoa and DC consumption can reduce stress, stimulate brain function, fight cancerous cells, improve circulation, mood, memory, immune system, and even protect the heart [12] , and liver tissue [10] .…”

“…Dark chocolate for management of NAFLD rich in bioflavonoids (flavanols, polyphenols, and theobromine) [12] , which has the highest antioxidant level in comparison with other food sources based on Oxygen Radical Absorbance Capacity measurement [13] . Besides nutrients such as saturated fat (60%), monounsaturated fat (35%), and linoleic acid (3%), chocolate contains important minerals such as potassium and magnesium [14] as well as cocoa, which is the main and the quintessential ingredient in chocolate [10] .…”