Taste is a weird thing. Defined as “a homeostatic function that aids in deciding what to eat,” it can vary quite substantially among people. For example, I find marmite, the often-polarizing food, absolutely repulsive; meanwhile, my wife enjoys it on toast. Conversely, she has a strong dislike for parsnips, while I like nothing better than a couple roasted up and eaten along with a side of beef. The ability to detect different tastants—chemicals that drive flavor—can also differ in the magnitude by which it occurs, leading some people to be labeled as supertasters (and tending to dislike coffee and Brussel sprouts). What we taste is subject to a variety of different influences, including smell and visual stimuli, and also social and cultural factors.
In recent years, those involved in sport have become increasingly interested in the effects a variety of tastes can have on performance. A couple of years ago, I wrote a post for SimpliFaster about how strong spicy flavors might act as a treatment for muscle cramps. Other research demonstrates how both sweet and bitter tastes, as well as cooling sensations mediated through taste, may help improve performance.
Based on this research, I recently co-authored a really interesting paper published in the European Journal of Nutrition, which asked, “Can taste be ergogenic?” We explored the influences of sweet and bitter tastants on performance, how thermal tastants (both hot and cold) can influence our capacity to exercise, and whether these performance-enhancing effects were due to taste itself or placebo or expectancy mechanisms. Here, I’ll share the key points with you.
Sweet and Bitter Tastes
In day-to-day life, the main sweet taste we’re exposed to comes from simple carbohydrates—essentially, sugar. We’ve long known that carbohydrates positively influence exercise performance, especially in endurance activities where athletes often consume carbohydrate-containing drinks, gels, and bars during competitions. Over the last couple of decades, however, researchers have started to notice something interesting: we see an improvement in performance when we consume carbohydrates during exercise, but only around 25% of the carbohydrate consumed during exercise enters our bloodstream to be used as energy.
This is much less than expected, given the performance-boost carbohydrate delivers. The finding led other researchers to speculate that—when consumed during exercise—carbohydrates might stimulate pathways within the brain and central nervous system. Two main proposed pathways are thought to be activated:
- Those associated with reward
- Those associated with feelings of energy availability
On the latter point, when we exercise, our brain consistently makes calculations between how much energy we have left and how long the exercise is due to carry on and uses the results of these calculations to regulate effort. When our brain senses that our energy stores are running low, it subconsciously drives us to slow down. When we consume carbohydrates during exercise, the sweetness activates taste receptors that tell our brain “energy is coming,” allowing it to modify the effort we’re putting in.When we consume carbohydrates during exercise, our brain loans us the energy we're expecting to digest soon, says @craig100m. Click To Tweet
Essentially, we’re loaning the energy from the carbohydrate we expect to digest in the next short period of time. We know this happens because we can trick the brain into thinking energy is coming by rinsing a carbohydrate around the mouth and spitting it out; when we do this, exercise performance is still enhanced.
The relationship between carbohydrates, sweet taste, and performance is somewhat complicated. Carbohydrates that don’t have a strong sweet taste, such as maltodextrin, have performance-enhancing effects when rinsed around the mouth. In contrast, very sweet flavors that have no energetic value—such as artificial sweeteners—don’t exhibit an ergogenic effect. Overall, this suggests that taste per se does not enhance performance. Instead, the carbohydrate molecules bind to some as-of-yet-unidentified receptors in the mouth. A further important area to consider here is that carbohydrate mouth rinses could lead to oral health issues, which commonly affect athletes and have important impacts on performance—something we should consider before using them.
Bitter tastes appear to activate similar regions of the brain as sweet tastes, leading researchers to wonder whether they could enhance performance similar to carbohydrate mouth rinses. The idea has been most well-explored by an Australian research group. In one study, the authors gave a group of male cyclists a solution made to taste bitter by adding quinine—the compound that gives tonic water its bitter taste. When the cyclists rinsed the solution around their mouths and then ingested it, they experienced an almost 4% performance improvement compared to when they rinsed and swallowed water. When a similar bitter solution was swilled around the mouth and not ingested, performance did not improve—which suggests that ingesting the bitter solution is what’s important. The researchers proposed this reason: there are a large number of bitter taste receptors situated in the upper gastrointestinal tract, and swallowing the solution activates these receptors and, hence, performance enhancement.
Like quinine, caffeine is a bitter tastant that activates bitter taste receptors in the mouth. Caffeine is also exceptionally well-established as an ergogenic aid, which begs the question: Are some of caffeine’s ergogenic effects due to its bitter taste? I explored this in detail in a separate paper published in 2019; a key difficulty with this suggestion is that caffeine mouth rinses don’t seem to enhance performance when the caffeine is not swallowed.
As anyone who enjoys a tasty curry will know, humans have used spices in their diet for years, including those that cause sensations of heat. The main chemical compound that drives these feelings is capsicum, which we find in foods such as chili. Creams and ointments that contain capsicum give a sensation of heat when rubbed on the skin, demonstrating the potentially broad use of this compound. Using capsicum as an oral pre-exercise supplement has received increased attention over the last couple of years, with a few studies exploring capsicum’s effects on exercise performance. Capsicum supplementation improved 1500m time trial performance, total reps in a reps-to-failure protocol carried out at 70% 1RM in the back squat exercise, and time to exhaustion in a repeated treadmill running exercise. Importantly, capsicum consumed as part of a meal doesn’t appear to elicit the same effects, so it’s likely that specific, targeted capsicum consumption in tablets is required.
However, before we all rush off and start purchasing—and taking—capsicum supplements, it’s important to consider that side effects are very common. The most common of these is gastrointestinal (GI) distress. Consuming this very spicy compound is associated with GI pain and diarrhea, as many people can attest to from experience. These effects have the very real potential to limit performance, which presents the main limitation of capsicum supplementation.
Conversely, menthol—a common flavor in toothpaste and mouthwash—elicits a cooling sensation. These sensations can have important implications when it comes to exercise performance, as feelings of overheating are linked to reduced performance. Early studies have demonstrated the somewhat minor effectiveness of menthol mouth rinses on endurance performance, which appear to be largely mediated through improvements in thermal comfort. However, no change in body temperature occurs.
The Important Role of Placebo
The placebo effect refers to the “desirable outcome resulting from a person’s expected and/or learned response to a treatment or situation.” This is crucial from a taste perspective; if an athlete consumes an ergogenic aid with a strong taste, and then sees a performance improvement, they will associate that taste with the improvement. And when they consume the same supplement on a different occasion, they will expect their performance to improve. Given that the effects of placebos on exercise performance are real and replicable, there is the potential that some of the ergogenic effects of any supplement are due partly to the athlete recognizing a taste they expect will improve performance and perform better as a result.
If this sounds implausible, consider the results of this case study, in which a child with an autoimmune disease received medication along with a strong taste and smell. After a period of time, the medication was removed from the cocktail, with only the taste and smell remaining; after consumption, the new “medicine” improved the patient’s symptoms. This isn’t to say the placebo effect exclusively mediates the potential ergogenic effects of taste but that it’s at least a contributor.
In summary, we found that taste has the potential to improve performance. It can be difficult, however, to separate the effects of taste per se and the stimulation of specific receptors in the mouth and gastrointestinal tract that provide signals to the brain regarding aspects such as energy availability. At present, it appears that carbohydrate and menthol mouth rinses have the potential to enhance performance. And ingesting bitter tastants and capsicum may also improve performance, although not because they stimulate the taste receptors.Carbohydrate & menthol mouth rinses as well as bitter tastants and capsicum may enhance performance, though the mechanisms by which they work differ. Click To Tweet
As the research in this area expands, we should get a better idea of how strong tastes enhance performance, and how we can harness this knowledge for athletes. An important part of using any ergogenic aid is that of placebo and expectancy; if the athlete believes something will improve performance, it likely will, and so strong, recognizable tastes form a part of this—and might be something for supplement manufacturers to consider in the future!
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