Anderson GH, et al. – This study was performed in healthy young men to assess the impacts of adding monosodium glutamate (MSG) to carrot soup with or without whey protein, on subjective appetite, food intake (FI) and satiety hormones. No influence on FI was observed, of adding MSG alone, or in combination with whey protein, to carrot soups. However, an increase in fullness and reduction in desire to eat, as well as subjective appetite, was attributed to MSG, which when added to protein decreased blood glucose and increased insulin and C–peptide, offering some support for the hypothesis that MSG in the gut signals protein consumption.

Methods

• Researchers used a repeated-measures, within-subject, crossover design to conduct 2 experiments.
• In exp-1 healthy young men (n = 28) consumed water alone (500 mL), or carrot soup (500 g) with or without MSG (5 g, 1% w/w) or whey protein enriched (36 g) carrot soup with or without MSG (5 g, 1% w/w).
• They measured subjective appetite post-treatment and FI at a meal at 120 min.
• In exp-2 (n = 15) the same treatments except for water were used.
• They measured blood glucose, insulin, glucose like peptide 1 (GLP-1), C-peptide and ghrelin in addition to subjective appetite and FI.

Results

• Findings demonstrated no impact on FI of adding MSG to carrot soup or whey protein enriched carrot soup.
• However, researchers observed that in exp-1 the addition of both MSG and protein increased fullness, and when MSG was added to carrot soup reduced desire to eat.
• Data also revealed that in exp-2, average post-treatment appetite (5–120 min) was lower after carrot soup with MSG and protein than all other treatments (P < 0.05).
• Additionally, results highlighted that in exp-2, carrot soup with MSG and protein, but not with protein alone, increased post-treatment insulin and C-peptide, and lowered blood glucose in comparison to carrot soup with no additions (P < 0.05).