Obese women have lower monosodium glutamate taste sensitivity and prefer higher concentrations than do normal-weight women

Abstract

The goal of this study was to determine whether obese women exhibit altered umami and sweet taste perception compared to normal-weight women. A total of 57 subjects (23 obese and 34 normal weight) participated in a 2-day study separated by 1 week. Half of the women in each group were evaluated using monosodium glutamate (MSG; prototypical umami stimulus) on the first test day and sucrose on the second test day; the order was reversed for the remaining women. We used two-alternative forced-choice staircase procedures to measure taste detection thresholds, forced-choice tracking technique to measure preferences, the general Labeled Magnitude Scale (gLMS) to measure perceived intensity of suprathreshold concentrations, and a triangle test to measure discrimination between 29 mmol/l MSG and 29 mmol/l NaCl. Obese women required higher MSG concentrations to detect a taste and preferred significantly higher MSG concentrations in a soup-like vehicle. However, their perception of MSG at suprathreshold concentrations, their ability to discriminate MSG from salt, and their preference for sucrose were similar to that observed in normal-weight women. Regardless of their body weight category, 28% of the women did not discriminate 29 mmol/l MSG from 29 mmol/l NaCl (nondiscriminators). Surprisingly, we found that, relative to discriminators, nondiscriminators perceived less savoriness when tasting suprathreshold MSG concentrations and less sweetness from suprathreshold sucrose concentrations but had similar MSG and sucrose detection thresholds. Taken together, these data suggest that body weight is related to some components of umami taste and that different mechanisms are involved in the perception of threshold and suprathreshold MSG concentrations.

Figure 1

Taste detection thresholds in normal-weight and obese women. (a) MSG and (b) sucrose detection thresholds of normal-weight (gray bars) and obese women (black bars). Data are presented as median ± SIQR. *P < 0.05, significantly different. MSG, monosodium glutamate; SIQR, semi-interquartile range.

Figure 2

Taste perception in normal-weight and obese women. (a) Perceived savoriness and (b) saltiness of increasing MSG concentrations and perceived sweetness of increasing (c) sucrose concentrations for normal-weight (open symbols) and obese (closed symbols) women using gLMS. The y axis labels represent gLMS notation. BD, barely detectable; gLMS, general Labeled Magnitude Scale; M, moderate; MSG, monosodium glutamate; W, weak.

Figure 3

Taste perception by discriminator status. (a) Perceived savoriness and (b) saltiness of increasing MSG concentrations and perceived sweetness of increasing (c) sucrose concentrations for discriminating (open triangles), semidiscriminating (open inverse triangles), and nondiscriminating subjects (closed triangles) using the gLMS. The y axis labels represent gLMS notation. *P < 0.05, significantly different from intensity perceived at 0.00 mol/l MSG within each group. Different letters signify significant differences (P < 0.05) between groups. BD, barely detectable; gLMS, general Labeled Magnitude Scale; M, moderate; MSG, monosodium glutamate; W, weak.