Acquired flavor acceptance and intake facilitated by monosodium glutamate in humans

Abstract

Monosodium glutamate (MSG) is known to enhance liking for the flavor of savory foods, but 2 whether associations between flavors and effects of MSG lead to changes in subsequent liking and intake for the flavor alone is unclear. To test this, 32 volunteers evaluated and consumed a 4 novel savory soup with no added MSG before and after four training sessions where the same soup was consumed either unchanged (Control) or with added MSG. The addition of MSG 6 during training increased both pleasantness and savory character of the soup and resulted in a larger increase in rated pleasantness of the soup in the MSG-trained relative to control 8 condition when the soup was re-evaluated post-training without MSG. There was also a significant increase in voluntary soup intake post-training after the soup had been paired with 10 MSG but not in the Control condition, and rated hunger increased more after tasting the soup post-training in the MSG-trained but not Control condition. These findings demonstrate that 12 co-experience of a savory flavor and MSG can result in increased subsequent liking and intake for the flavor in the absence of MSG, and possible explanations for how MSG reinforces 14 learning are discussed. 16

Monosodium Glutamate Toxic Effects and Their Implications for Human Intake: A Review

“…While obesity after MSG diet in rats could be the result of leptin resistance (Dolnikoff et al 2001), in humans MSG could lead to obesity due to the increase in the intake of high caloric savory foods, in which MSG enhances liking resulting in learning reinforcement (Bannai andTorii 2013, Yeomans et al 2008). In accordance with this hypothesis is the finding of a significant increase of hunger and savory flavor soup intake, even in the absence of MSG, which has been observed in a group of volunteers previously trained in four sessions where the soup was consumed with added MSG (Yeomans et al 2008). However, the opposite results including subjective assessments of hunger have been shown in adults supplemented for 6 days with a nutritional dose of MSG (2 g/day).…”

Consumption of monosodium glutamate in relation to incidence of overweight in Chinese adults: China Health and Nutrition Survey (CHNS)

“…Concern has been raised about MSG as a risk factor for epidemic obesity because data from both animal models (7)(8)(9)(10) and human studies (11,12) suggest a possible link between MSG and overweight/obesity. Potential mechanisms for the MSG-obesity link include the possible influence of MSG on energy balance by increasing palatability (13,14) and by disrupting the hypothalamic signaling cascade of leptin action (15,16).…”

Flavours: the pleasure principle

“…Thus, pairing novel odours with glutamate in soup increases liking for those odours, but in addition, exposure to the flavour following conditioning also increased feelings of hunger and increased consumption of the soup, relative to simple repeated exposure to the soup [11]. This suggests a mechanism for the development of food 'wanting' , a distinct construct from 'liking' that has been explored in terms of both distinct neural and motivational substrates [12,13].…”