There's an alternative available for endurance athletes who are concerned about the healthiness of sugar bombs like sports bars, gels and drinks. Bananas work just as well as sports drinks, write sports scientists at Appalachian State University in PloS One.
During intensive exercise bouts, according to the text books, carbohydrate-rich foods with a high glycaemic index are best for endurance athletes. Bananas do not fall in this category.
Neither do grapes, mangos, pineapple, raisins, honey and orange juice, all of which have a glycaemic index of about fifty. That's considered low-to-medium, so unsuitable as a source of carbohydrate for endurance athletes' training.
But even so… Studies show that endurance athletes perform better after consuming a meal with a low glycaemic index than a meal containing large amounts of high-glycaemic foods, and athletes that derive carbohydrates from raisins perform just as well as athletes who use gels or other super foods.
When these studies came to the notice of the banana sales executives at Dole Foods [dole.com], they thought to themselves: we should try this too. So Dole handed a stack of money over to Appalachian State University to do the experiment described in this article.
The researchers got 14 trained cyclists aged between 14 and 45 to cycle 75 kilometres on two occasions. During each ride the subjects were given 0.2 g carbohydrates per kg bodyweight every 15 minutes. On one occasion the carbs were given in the form of a sports drink; on the other they came in the form of bananas.
It made no difference where the carbs came from; the cyclists performed the same, the researchers discovered.
Sorry, we have no table or figures for you. The researchers didn't produce any. They were too busy with their new game: metabolomics. This sport enables you to measure the presence of multiple conversion products simultaneously.
The researchers discovered that there was more interleukin-8 and interleukin-10 present in the athletes' blood when they had eaten bananas.
Both of these interleukins activate the innate immune system. You can speculate that endurance athletes who get their carbs from bananas are less likely to catch a viral infection.
The researchers also discovered that the bananas led to a rise in the dopamine concentration in the subjects' blood.
When the researchers analysed the bananas they found out what had caused the rise in dopamine level. 100 g banana contains 0.42 mg dopamine. The cyclists had consumed 6-7 bananas, so had ingested about 3.33 mg dopamine.
The researchers exclude the possibility that the dopamine makes its way to the brain. It's possible that dopamine derived from food might enable the heart muscle to work harder. That didn't happen in this study; the rise in dopamine level wasn't high enough for that.
But, write the researchers, banana peel contains higher quantities of dopamine than the fruit itself. "Future studies with banana peel-based supplements will reveal if high oral dopamine intake is advantageous for endurance athletes using similar performance and physiological outcomes", the researchers announce.
We're waiting with bated breath.
PLoS One. 2012;7(5):e37479.