Sucrose and non-nutritive sweeteners can suppress the bitterness of vegetables independent of PTC taster phenotype

The unpleasant bitter taste found in many nutritious vegetables may deter their consumption. While bitterness suppression by sweeteners is well-studied in the chemical and pharmacological fields (Ley Chem Percept, 1:58-77, 2008), less is known about the interaction of sweeteners with the bitterness of functional foods such as vegetables. We investigated whether sweeteners decreased the bitterness of vegetables as a step toward increasing consumption. Our secondary aim was to determine whether this effect was influenced by individual variation in bitterness perception, as assessed by phenylthiocarbamide (PTC) tasting ability. In Experiment 1, 111 college students tasted and rated plain broccoli and cauliflower, then received one with the addition of sucrose. In Experiment 2, we replaced broccoli with Brussels sprouts, which are generally perceived as highly bitter (Tepper Am J Hum Genet, 63:1271-1276, 1998), and replicated the study with 76 new participants. In Experiment 3, 224 participants tasted Brussels sprouts plain and with the addition of sucrose, saccharin, aspartame, or sucralose. In all experiments, sensitivity to PTC was also measured using suprathreshold scaling with an updated generalized labeled magnitude scale. The reported bitterness of the vegetables was significantly decreased by the addition of sweeteners in each study, all p values of <0.001. In Experiment 3, the non-nutritive sweeteners (NNS) functioned identically to sucrose in suppressing bitterness and increasing palatability. The effect of the sweeteners did not vary by the participants' PTC taster phenotype, which was treated as a continuous variable in a linear regression analysis (all R ² < 0.05). The addition of sweeteners to vegetables reduces the bitterness that many consumers find objectionable. This robust effect was found for vegetables that varied in their perceived bitterness and regardless of individual differences in bitterness sensitivity. Importantly, the finding that NNS are as effective as sucrose at suppressing bitterness implies that sweeteners can be incorporated into the diet without the addition of calories. Furthermore, by the principles of flavor-flavor learning sweeteners will come to condition a preference for vegetables plain.