Athletes are consuming increasing amounts of nutritional supplements to improve their athletic performance, sometimes without considering their health. Some of the most common health problems experienced by long distance athletes are gastrointestinal problems: nausea, vomiting, abdominal pain, diarrhea, and bloody stools, with a prevalence of 30-90% that often leads them to abandon their competitions (1). The source of these problems seems be a combination of physiological and mechanical causes that may be affected by nutritional factors. The consumption of fiber or fat prior to training or competition seems to increase these symptoms, while a diet rich in different types of carbohydrates and foods that increase the production of nitric oxide improve these symptoms (1). The studies that have been conducted to determine the influence of different dietary components on the gastrointestinal symptoms associated with exercise have been one-off. In these studies the composite or food (carbohydrates, citrulline, dairy) was given in a meal prior to exercising (2,3). However, until now, there has never been a study involving prolonged nutritional intervention over time in order to improve the gastrointestinal problems associated with physical exercise.
Cacao is rich in flavanols, specifically procyanidins and catechins, which give it antioxidant and heart-protecting properties (4). The procyanidins in cacao cause vasodilation in different ways associated with nitric oxide (NO). Thus, the production of gastric NO is strengthened in the presence of nitrate (5). They also have a local and systemic anti-inflammatory effect, interfering with the metabolism of eicosanoids. The result is the reduction of proinflammatory cytokines and the increase of anti-inflammatory cytokines (6,7).
The flavanols present in cacao have also shown a moderating effect on intestinal microbiota. The majority of procyanidins in cacao reach the colon where they are metabolized and they in turn modify the intestinal microbiota. Few studies address the intestinal microbiota modifications linked to the consumption of cacao, but all coincide in that its consumption has a prebiotic effect, increasing the presence of the genera Lactobacillus and Bifidobacterium, which strengthen the gastrointestinal barrier between different mechanisms (8,9). Therefore, the modifications to microbiota may increase the resistance of the intestinal barrier and reduce the symptoms and potential future infections in athletes experiencing the alteration of the gastrointestinal barrier.
Until now, studies on the use of cacao in supplements for athletes have been limited and mainly focused on determining their effect on performance and oxidative stress. It has been observed that regular consumption of dark chocolate reduces oxidative stress levels during exercise (10,11). However, only a limited and transitory effect has been observed in the oxidative effect arising in DNA during exercise (12). With regard to performance, a recent study showed that a chocolate drink consumed in the recovery phase after a long climbing session reduced muscular pain, facilitating recovery (13), and increased the amount of time before cyclists experienced exhaustion (14).
That is why the Universidad Europea MAS (Microbiota, Nutrition, and Health) research team is working on a new research project. This project focuses on chronic interventions, providing long distance athletes with cacao rich in flavanols in order to determine their influence on the strength of the intestinal barrier through microbial modulation.
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10. Wiswedel I, Hirsch D, Kropf S, Gruening M, Pfister E, Schewe T, et al. Flavanol-rich cocoa drink lowers plasma F(2)-isoprostane concentrations in humans. Free Radic Biol Med. 2004 Aug;37(3):411–21.
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