The Sweetness Paradox: Mounting Evidence Challenges the “Sweet Tooth” Hypothesis

Contrary to common belief, exposure to sweet foods and beverages does not necessarily increase liking for sweetness, as multiple recent studies have shown.

It’s a widely accepted notion that exposure to sweet foods and beverages drives us to crave more sweetness – the so-called “sweet tooth” effect.

This idea is so pervasive that it’s often stated as fact by health authorities and in scientific literature.

But does it actually hold up to rigorous scientific inquiry?

To find out, researchers David J. Mela and Davide Risso examined the evidence, conducting an extensive review of intervention trials and longitudinal cohort studies examining the relationship between sweetness exposure and subsequent sweetness liking.

Their paper Does sweetness exposure drive ‘sweet tooth’? was published in the British Journal of Nutrition on February 26, 2024.

Putting the Hypothesis to the Test

The review builds upon previous systematic analyses, incorporating the latest research up through February 2024.

The authors identified 11 intervention trials published since 2017 that assessed changes in sweetness liking after exposing participants to sweet vs. non-sweet stimuli.

These trials were conducted in a range of populations, from infants in Ghana to adults in the Netherlands, and employed varying methodologies.

For example, a trial in 49 German adults compared the effects of consuming a high-sugar, high-fat yogurt twice daily for 8 weeks versus a low-sugar, low-fat version.

Another study in 985 Ghanaian infants tested the impacts of providing a sweetened nutrient supplement daily from birth to 18 months.

The researchers also examined recent longitudinal cohort studies, including one that followed over 500 French children from infancy to ages 8-12, tracking associations between early sugar intake and later sweetness preferences.

The Results: A Not-So-Sweet Surprise

Across these diverse studies, a consistent pattern emerged: contrary to the prevailing “sweet tooth” hypothesis, sweet taste exposure did not appear to drive increased liking for sweetness.

As Mela and Risso report:

“None of the recent trials involving acute or sustained sweet exposures followed by assessments of generalised liking found that these exposures increased the liking or choice of sweet stimuli or foods.”

In the 8-week yogurt trial, for instance, there were no significant differences in sweetness liking between the high-sugar and low-sugar groups.

The Ghanaian infant study found no effect of the 18-month sweetened supplement on preferences for sweet foods or beverages at ages 4-6.

And the French cohort study observed no significant associations between infant sugar intake and reported sweetness liking in late childhood.

Intriguingly, several of the intervention trials found that short-term sweet taste exposure often reduced subsequent desire for sweetness – the opposite of the hypothesized effect.

A single exposure to a sweet beverage decreased adult participants’ positive ratings for sweet foods by as much as 20-30% relative to water.

Caveats and Future Directions

The authors acknowledge limitations of the current evidence base, noting inconsistencies in methodologies and a lack of studies in certain populations.

There are also unanswered questions about potential differences between sugar and low-calorie sweeteners.

But the overall body of evidence points away from the notion of a simple, universal “sweet exposure → sweet liking” relationship.

Instead, the reality appears to be far more complex, likely shaped by a tapestry of biological, psychological, and contextual factors.

To unravel this “sweetness paradox”, Mela and Risso argue for more standardized, rigorously-designed studies, especially in currently under-represented populations and testing a wider variety of sweeteners.

By better understanding the true drivers of sweet taste preference, we may be able to craft more effective, evidence-based strategies for promoting healthy food choices and eating habits.

Study information:

  • Title: Does sweetness exposure drive ‘sweet tooth’?
  • Authors: David J. Mela and Davide Risso
  • Publication Date: 26 February 2024
  • Journal: British Journal of Nutrition
  • DOI: 10.1017/S0007114524000485