Abstract

Fructose is credited with some advantages over sucrose: it causes less of an increment in plasma glucose and insulin response, and the taste is sweeter. We reevaluated the latter property with a new methodology (the “up and down” method adapted from Dixon) in 33 healthy subjects, 17 insulin-dependent diabetes mellitus (IDDM) patients, and 12 non-insulin-dependent diabetes mellitus (NIDDM) patients. Sweetening potency was determined over 2–3 test sessions in each subject. Results are expressed in percent as the relative sweetness (R) of fructose (F) over sucrose (S), taken as reference. In the first set of experiments, with a 30-g/L sucrose-water solution at pH 7, we found that R values were similar for healthy subjects (102 ± 8%) and diabetic subjects (106 ± 7%) (P < .05). No significant difference between IDDM and NIDDM patients was observed. In a second set of experiments, performed in healthy subjects only, R was increased in acid water (114%; P < .01), in lemon juice (136%; P < .001), in water at 2°C (130%; P < .001), and in coffee at 2°C (120%; P < .02); mean values were decreased in grapefruit juice (77%; P < .001), in water at 43°C (88%; P < .01), and in coffee at 53°C (87%; P < .001). We found that the test methodology had a very satisfactory intrasubject reproducibility (coefficient of variation [C.V.] < 8%) but a very wide intersubject variability (C.V. ≃ 32%). We conclude that fructose has either an equal, higher, or lower relative sweetness compared with sucrose, depending on the physical and chemical characteristics of the solutions. The results were unpredictable for one given subject, but fructose seemed regularly sweeter in cold beverages than in hot ones. Diabetic individuals found fructose slightly but significantly sweeter than sucrose, but it is doubtful that this modest difference has any clinical implications.