Tuesday, September 23, 2014

Mono-Sodium Glutamate (MSG) As Dieting Aid for the Avg. Glutton? MSG "Preload" Reduces Total Energy Intake per Meal by 3-5% - Adding Extra Protein Amplifies the Effect

Spicy Carrot Soup (recipe) - Would it be more satiating, if it was made with MSG? The study at hand shows: Yes, if it's eaten as an entree, it will actually reduce your food intake more than an MSG-free soup, you'd eat before a meal.
Mono-sodium glutamate, or MSG, as it is usually called, is a strange molecule. Previous research suggests it may have a paradoxically biphasic effect on appetite: Just as common wisdom tells you, it will increase your appetite while you are eating an MSG-flavored meal due to its (umami) flavour enhancing effect. On the other hand, there is also irrefutable evidence to show that that MSG will enhance subsequent satiety - an effect of which scientists believe that it is brought about by its proposed role as a predictor of protein content.

In their latest experiment, Una Masic and Martin R. Yeomans from the University of Sussex wanted to elucidate, whether one could make use of the satiety effect without increasing the risk of overeating.
Artificial sweeteners have a similarly bad reputation as MSG.

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The Latest on the Sweetener Scare.

Sweeteners In- crease Sweet- ness Threshold
Suez In the corresponding trial, which involved a total of thirty-six low-restraint (not dieting or thinking "Oh my god, I am gonna be fat, when I eat this!") males (mean age: 21 years; BMI: 22 kg/m²).

On all test days, the subjects received identical breakfasts [80 g cereal (Crunchy Nut Cornflakes; Kellogg’s), 200 g semi-skimmed milk (Sainsbury’s plc) and 200 g orange juice (Sainsbury’s plc) (total 2107 kJ (503·6 kcal))] before they consumed a MSG or no-MSG carrot and spice soup as an entree for lunch.
Figure 1: Graphical representation of the timings of the preload and ad libitum meals and the appetite ratings made on each test day.↓, Appetite rating made;■, fixed meal; □, ad libitum meal (Masic. 2014).
Subsequently, the scientists served pasta in tomato sauce followed by ice cream and recorded the amount of food the subjects ate.
Study shows insulin  sensitiziing effects of dreaded food additive | learn more
This is not the first study suggesting that MSG is not "all bad": Actually I have written about beneficial effects of MSG before. About it's insulin sensitizing effects in "Glutamate: Can It Be Use To Your Advantage? Study Shows Insulin Sensitizing Effects of Dreaded Food Additive" (read more) and about its beneficial effects on gut health in "Pigs Would Pick MSG - Glutamate Seals the Gut, Decreases Liver & Muscle Fat & Increases Plasma Amino Acids in Swine" (read more). So, maybe - just maybe, obviously, it's not all that bad, after all... well, one thing we should keep in mind though, is the fact that there is still the issue with attention deficit and other cognitive disorders, of which Thomas J. Sobotoka writes in a 2010 review that the evidence is insufficient.
Unlike the ADHD connection, the headaches and other symptoms some people suffer from, when they ingest large amounts of MSG are non-debatable, though. For me, personally, the existence of these effects is reason enough, not to use MSG deliberately as a supplement. It's yet not enough to run away, when I occasionally realize a food item I am about to eat contains some mono-sodium glutamate.
This simple procedure was repeated thrice. On occasions one and two with a soup with only 117kcal/100g, on occasion three and four and five and six with larger entrees containing ~280kcal/100g and either a balanced protein (45% pro / 38% cho) or high carbohydrate (2% pro / 81% carbohydrate) content.
Figure 1: Rel. changes in energy intake (% of non-MSG entree) in response to the consumption of MSG vs.
non-MSG carrot and spice soup as an entree (Masic. 2014)
The results were as expected (by the scientists, not by the layman ;-): There was a larger decrease in subsequent energy intake with the MSG soup as an entree.

Moreover, a larger preload produced a more significant reduction in energy intake on the subsequent main dish (Pasta) and dessert (Ice cream), than a small one. And last but not least, there was a significant advantage for the balanced, higher protein, lower carbohydrate version of the soup that had been spiked not just with MSG, but also with whey (in both the active and control trial; see Figure 1, right bars).
Wtf, how does this work? The authors suggest two possible explanations. Firstly, the sensory quality generated by the addition of MSG may have made the experience of protein more salient, and did thus enhance the satiating effects of protein in the meal. Alternatively, the improved compensation of protein in the MSG+ condition could be related to a post-ingestive sti- mulation of gut glutamate sen- sors which have been related to enhanced satiety in animal studies (Niijima. 2000; San Gabriel. 2007; Kondoh. 2008).
Bottom line: Overall, the study at hand clearly refutes the commonly held believe that MSG would make you overeat. Rather than that, an MSG preload has similar effects as the previously discussed whey preload before a meal (learn more).

And while the effect does not depend on the presence of additional protein in the MSG-containing entree, it is amplified (albeit non-significantly), if the soup, or whatever else you may be eating before your main dish, contains both MSG and a high amount of protein (see Figure 1, right). As the authors say their evidence does therefore clearly "suggest that moderate increases in the energy content of a food through the addition of protein and MSG, for example as a savoury snack, may reduce the likelihood of subsequent overconsumption" (Masic. 2014) - a result that goes against almost everything you'll read about MSG on the Internet | Comment on Facebook!
  • Kondoh, Takashi, and Kunio Torii. "MSG intake suppresses weight gain, fat deposition, and plasma leptin levels in male Sprague–Dawley rats." Physiology & behavior 95.1 (2008): 135-144. 
  • Monosodium glutamate delivered in a protein-rich soup improves
    subsequent energy compensation
  • Niijima, Akira. "Reflex effects of oral, gastrointestinal and hepatoportal glutamate sensors on vagal nerve activity." The Journal of nutrition 130.4 (2000): 971S-973S. 
  • San Gabriel, Ana M., et al. "mGluR1 in the fundic glands of rat stomach." FEBS letters 581.6 (2007): 1119-1123.
  • Sobotka, Thomas J. "Overview and Evaluation of Proposed Association Between Artificial Food Colors and Attention Deficit Hyperactivity Disorders (ADHD) and Problem Behaviors in Children." US FDA Food Advisory Committee Meeting Materials-Interim Toxicology Review Memorandum (Certified Color Additives). 2010.