Table 9.

Summary of clinical studies on MSG impact on food consumption and energy intake

Number of participants (characteristics)	Vehicle for MSG	Study protocol	Results	Reference
26 volunteers (age 18–34 years old; mean BMI 22.7 kg/m2)	Spiced carrot soup	3 hours after standardized breakfast, volunteers received 450 g of (a) low energy or (b) high-energy, high-carbohydrate and protein soup preload with added MSG/IMP [0.6% MSG (w/w) and 0.25% (w/w) IMP] or without MSG/IMP. Changes in appetite during soup intake and at a subsequent (after 45 minutes) ad libitum lunch were recorded.	Increase flavor and immediate appetite but reduced subsequent ad libitum test meal intake regardless of the protein content of the soup.	(Masic & Yeomans, 2014b)
35 volunteers (age: 18–28 years old; mean BMI: 22 kg/m2)	Spiced carrot soup	3 hours after standardized breakfast, volunteers received 450 g of (a) low energy, (b) high-energy high-carbohydrate or (c) high-energy high-protein soup preload with added MSG [1 % (w/w) MSG] or without MSG. Changes in appetite during soup intake and at a subsequent (after 45 minutes) ad libitum lunch were recorded.	MSG addition enhances significantly compensation for energy added as protein There were no differences between MSG or specific macronutrient conditions in rated satiety over the course of testing after preload intake.	(Masic & Yeomans, 2014a)
30 infants (age: 1.0–3.7 months; Weight-for-length percentile at study entry: 63.9 ± 4.9)	Milk formula	Infants received iso-caloric formulas: (a) CMF (cow milk formula) - low in free amino acids and small peptides (b) ePHF (extensive protein hydrolysate formula) - abundant in free aminoacids and small peptides or (c) cow milk formula with added free glutamate 84 mg/100 mL. A second meal of CMF was given when hunger was signaled again	Infants consumed less of formulas higher in free glutamate than of an iso-caloric formula lower in free glutamate, yet showed equivalent levels of satiation and greater levels of satiety.	(Ventura, Beauchamp, & Mennella, 2012)
33 elderly individuals (age: 74.6–87 years old; BMI: 21.3±2 kg/m2) and 29 young subjects (age: 19.1–23.5; BMI: 27.4±4.9 kg/m2)b)	Mashed potatoes, spinach and ground beef	Volunteers rated pleasantness (10-point scale) of the 3 foods each with 0 g, 0.5 g, 0.8 g, 1.3 g and 2.0 g of MSG/100 g	0.5% MSG (p<0.05) was preferred in mash potatoes. No optimal concentration was found for the other courses.	(Essed, Oerlemans, et al., 2009)
53 elderly (age: 74.6–87 years old; BMI: 26.5±4.2 kg/m2)		Volunteers received 2 cooked meals with MSG (0.5% in mashed potatoes, 2% in spinach and ground meat) and without MSG in random order (single blind, cross-over design) within four weeks.	MSG 0.5% and 2% did not increase food intake in elderly people.
83 elderly individuals institutionalized in a nursing home (age: 79.2–94.1 years old)	Cooked meal	The participants were randomly assigned to the control group (placebo 1 g maltodextrine; n=25), the MSG group (300 mg MSG + 700 mg maltodextrine; n=24), the flavor group (700 mg flavor + 300 mg maltodextrine; n=26) or to the flavor plus MSG group ((700 mg flavor + 300 mg MSG; n=25) for 16 weeks. Anthropometry data (body weight, body composition), dietary intake of the cooked meal, pleasantness and appetite data were assessed	Body fat, total body water, and extra cellular water did not change within any of the four groups; No differences were found in changes in energy intake between groups.	(Essed et al., 2007)
120 elderly adults (age: 72±6 years old)	Tomato soup	Participants received (a) 1,200 mg/L MSG (0.12% MSG) + 3 g/L celery powder versus (b) non-enhanced soup. The effect on intake and pleasantness were assessed.	No difference in intake, liking, and strength between the soups was found; No difference was reported within the low olfactory/low gustatory group (elderly vs young).	(Essed, Kleikers, et al., 2009)
35 women (age: 20–40 years old; BMI: 18.5–24.9 kg/m2)	Chicken broth	Participants received: Preload 1 (given at 9:00 a.m.): 240 mL broth Preload 2 (given at 11:00 a.m.): 240 mL broth Ad libitum test lunch (12:30 a.m.) 4 sessions were conducted each using one ofthe following broths (preloads): (a) base chicken broth (base broth), (b) chicken broth with MSG and nucleotides (MSG 1.2 g/serving), (c) chicken broth with MSG (MSG 1.2 g/serving), and (d) chicken with added fat.	Hunger and desire to snack between the second preload exposure and the test meal were significantly reduced in the MSG condition relative to the base broth condition (both, p < 0.03); The addition of MSG to chicken broth did not increase energy intakes at lunch or affect motivational ratings over the entire testing session.	(Carter et al., 2011)
60 volunteers (age: 19–63; BMI: 20–30 kg/m2)	Soup stock	On two separate experimental sessions, each subject determined (using a single blinded design) the lowest detected concentration of (a) MSG or (b) MSG +IMP. MSG was added in concentrations of 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8% (w/w) and IMP’5 0.25% (w/w). On each day, subjects assessed the sensory properties of the soup and their ‘liking’ and ‘eating frequency’ of high carbohydrate, fat and protein food items.	The taste threshold (and therefore sensitivity) of MSG was lowered from 0.33±0.24% to 0.26±0.22%MSG when 0.25% (w/w) of IMP was added; ‘Liking’ and ‘preference’ scores for protein were found to be related to the threshold of MSG ± 0.25% IMP.	(Luscombe-Marsh et al., 2008)
22 volunteers (age: 19–63; BMI: 20–30 kg/m2)	Vegetable soup and rolls filled with minced meat	On five experimental sessions (single-blinded, randomized cross-over design), subjects consumed: preloads consisting in (a) control (water); (b) a high-protein meal + 0.6 % MSG w/w + 0.25 % IMP-5 w/w; (c) high-protein meal with no additives; (d) a high-protein meal + MSG 0.6% w/w; (e) sham-fed meal 2 (sham high-protein + MSG + IMP). ad libitum meal (after 30 minutes)	The addition of MSG to a high protein meal does not influence the perceptions of appetite or satiety. It increases significantly the energy intake at a second course vs. high-protein meal with no MSG; There was no significantly difference in the insulin and blood glucose responses between any of the high-protein conditions (with or without additives) (though GLP-1 values were higher for high-protein meal + MSG 0.6% vs. high-protein meal with no additives).	(Luscombe-Marsh et al., 2009)
86 women (age: 30–45; BMI: 20–26 kg/m2)	Chicken flavor broth	Volunteers received preload: (a) a low-energy chicken flavor broth (200 mL); (b) broth + MSG (0.5 g/100 mL) (c) broth + MSG + IMP (0.05 g/100 mL) ad libitum testing meal (snacks varying in taste and fat content)	MSG and MSG + enhanced savory taste and broth properties; MSG preload resulted in less. consumption of total energy, as well as energy from sweet and high-fat snacks vs control and reduced added sugar intake; These findings were not observed after MSG + IMP preload; Appetite ratings were not different across the three preloads.	(Imada et al., 2014)
13 volunteers (age: 30–50 years; BMI: 23–28 kg/m2)	Capsule	Dietary adaptation for 2×7days (cross-over, single-blinded design) Volunteers received with food (a) MSG 2 g/day or (b) NaCl 0.87 g On test day they received a test meal (38 g milk protein, 27 g fat, 99 g carbohydrate final volume of 600 mL) + (1) MSG 2g or (2) NaCl 0.87g.	MSG addition to the meal determines antral distension significant between 30 and 90 min vs. control. It elicited a significant increase in the area under the curve of plasma concentrations of glutamate, serine, cysteine, isoleucine, leucine, tyrosine, and ornithine at 60 or 120 min post-meal; MSG favors the interaction between time and treatment on hunger sensation, but the effect is not significant, nor the effect on fullness; No change in body weight, urea concentration, glycemia, plasma insulin, glucagon like peptide-1, and ghrelin vs control	(Boutry et al., 2010)