BACKGROUND: There are consistent, evidence-based global public health recommendations to reduce intakes of free sugars. However, the corresponding evidence for recommending reduced exposure to sweetness is less clear.
OBJECTIVE: Our aim was to identify and review the published evidence investigating the impact of dietary exposure to sweet-tasting foods or beverages on the subsequent generalized acceptance, preference, or choice of sweet foods and beverages in the diet.
Design: Systematic searches were conducted to identify all studies testing relations of variation in exposure to sweetness through foods and beverages with subsequent variation in the generalized acceptance, preference, or choice of sweetened foods or beverages, in humans aged >6 mo.
RESULTS: Twenty-one studies met our inclusion criteria, comprising 7 population cohort studies involving 2320 children and 14 controlled trials involving 1113 individuals. These studies were heterogeneous in study design, population, exposure, and outcomes measured, and few were explicitly designed to address our research question. The findings from these were inconsistent. We found equivocal evidence from population cohort studies. The evidence from controlled studies suggests that a higher sweet taste exposure tends to lead to reduced preferences for sweetness in the shorter term, but very limited effects were found in the longer term.
CONCLUSIONS: A small and heterogeneous body of research currently has considered the impact of varying exposure to sweet taste on subsequent generalized sweet taste preferences, and this evidence is equivocal regarding the presence and possible direction of a relation. Future work should focus on adequately powered studies with well-characterized exposures of sufficient duration.
Examining the research question: “does dietary exposure to sweetness in humans impact on the generalized acceptance, preference, choice, and/or intake of sweet taste in the diet?”, this systematic review of 21 studies by Appleton et al concluded that the evidence from controlled studies suggests that a higher sweet taste exposure (including from foods containing low calorie sweeteners) tends to lead to reduced preferences for sweetness in the shorter term, but very limited effects were found in the longer term.
The favourable findings of the short-term studies can be explained by earlier evidence on sensory-specific satiety, which suggests that exposure to a particular sensory attribute (e.g., sweetness) can lead to reductions in the apparent pleasantness and choice of foods and beverages with that same attribute, relative to others. Thus, exposure to sweet taste from dietary sources with low amounts of sugars (e.g. sweetened with low calorie sweeteners) may not only replace consumption of free sugars but could also reduce the desire for sweetness from other sources.
While evidence from population cohort (observational) studies is equivocal, the controlled and better-designed clinical studies show favourable results at least in the short term, and importantly, current evidence does not support public health and nutrition policies that call for a reduction of low calorie sweeteners’ use in the context of an overall reduction of sweetness and on the basis of a potential negative effect on habituation to sweet taste (sustained “sweet tooth”). Similarly, a review of literature by Public Health England in the UK (2015) concluded that there is little evidence for the theory that repeated exposure to sweetness can lead to habituation to sweet taste.