The “sweet tooth” hypothesis examined and rejected in a new review study
Highlights:
- Evidence from human studies does not provide support to the widespread assumption that sweetness exposure drives a “sweet tooth”, a review of multiple studies shows
- After consuming a sweet-tasting food or drink, the desire for sweetness and consumption of the same and other sweet foods are reduced, a well-established phenomenon called sensory-specific satiety
- Low/no calorie sweeteners may help to satisfy the desire for sweet taste with fewer calories
It is a common belief that the more we are exposed to sweet tasting foods or beverages in the diet, the more we crave for sweetness, a hypothesis also known as the “sweet tooth” effect. However, contrary to this widespread assumption, often stated as a fact in the literature and in public health policies, evidence from multiple studies do not confirm the ‘sweetness exposure driving sweet tooth’ causal pathway.
To assess if the “sweet tooth” hypothesis is supported by science, a recent study reviewed all latest research that have tested the relationship between sweetness exposure and subsequent liking in adults and children, and compared the results to those of previously published systematic reviews.1 The current article presents the conclusions of this new review study and further discusses the role of low/no calorie sweeteners in managing the desire for sweet taste.
Evidence does not support the “sweet tooth” hypothesis, a new review study shows
In a newly published study in the British Journal of Nutrition,1 David J. Mela and Davide Risso reviewed all recent clinical intervention trials and prospective cohort studies exploring sweetness exposure and subsequent liking, which have been published after the systematic review by Appleton et al (2018)2, the latest review paper on this subject to date.
A total of fifteen clinical controlled trials that measured or intervened in exposures to sweetened foods and beverages and reported an explicit measure of sweetness liking after exposure were identified and included in the review. None of the eleven interventions that involved acute or sustained sweet taste exposures resulted in increases in measures of sweet taste liking. In fact, acute exposures to sweetness generally decreased desire for and liking of the same and other sweet stimuli, a well-established phenomenon called sensory-specific satiety; sustained exposures had no significant or inconsistent effects. Four trials reporting on the effects of exposures to sweet vs non-sweet products followed by assessments of sweetness liking or choice within that same product format, generated a mixed pattern of results, mainly no significant effect of sweetness exposure or inconsistent results. The three included cohort studies in infants and children also reported no significant associations of exposures to sweetness with measures of sweet taste preferences.
The present conclusions are similar for research in adults and children, for low/no calorie sweeteners and sugars, and from both intervention trials and cohort studies.1 Three prior systematic reviews including the most recent by Appleton and colleagues have all come to similar conclusions that current evidence does not support the widespread belief that exposure to sweetness may encourage a “sweet tooth”.2,3,4
Taken together, in line with previous reviews, evidence from recent research does not support a relationship between sweetness exposure and subsequent liking for sweet taste.1 While there is sufficient evidence that excess sugars intake may have adverse health effects,5 there is no evidence that reducing exposure to overall sweetness in the diet, including from low/no calorie sweeteners, could facilitate adaptation to lower sweetness liking and sugar intakes, and more studies are ongoing on this subject.6 Public health guidance should therefore be cautious in expressing an assumption that is currently not supported by scientific evidence.
The role of low/no calorie sweeteners in managing our desire for sweet taste
It is well established that sweetness liking has an innate basis. While all humans express the same response to sweetness immediately after birth, preference for sweet taste changes over time and becomes highly idiosyncratic, with large inter-individual differences in adults.4 Some research suggests that humans fall into three phenotypic sweetness response patterns: those whose liking increases with sweetness intensity (sweet likers), those who show increasing dislike as sweetness increases (sweet dislikers), and a third group who show preference for moderate levels of sweetness.7 Therefore, managing the desire for sweet taste while limiting overconsumption of sugars should be an individualised dietary goal, especially important for those who have an increased liking for sweetness and/ or consume high amounts of sugars.
Research has shown that consuming low/no calorie sweetened food or drinks may satisfy the desire for sweetness and help individuals reduce the intake of sweet-tasting foods and drinks acutely, 8,9 or over sustained periods.10,11,12 It has also been shown that consuming low/no calorie sweetened drinks may help some individuals to control food cravings and feel greater meal enjoyment.13 Research also consistently confirms that the use of low/no calorie sweeteners may result in reductions in sugars and energy intakes and, in turn, in modest weight loss, as assessed in systematic reviews and meta-analyses of controlled human studies by the WHO and other researchers.14,15
In conclusion, current evidence does not support the notion that exposure to sweet taste in general, or to low/no calorie sweeteners in particular, can lead to a heightened liking for sweetness, or to increased consumption of sweet products, and in contrast, in many instances, low/no calorie sweeteners may contribute to satisfy a desire for sweetness and reduce the consumption of sugars and calories.
