Researchers look at how umami foods may influence our eating choices.
Umami, or savory taste, was first identified as an independent basic taste by Japanese chemist Kikunae Ikeda in 1908.
Since then, it came to be accepted as the fifth taste, which we perceive thanks to glutamic acid, which is an amino acid that occurs naturally in many foods.
A common source of glutamic acid — often used to make certain foods taste more savory — is monosodium glutamate (MSG).
MSG's role in health has been subject to intense debates over the years. Recently, researchers at Harvard Medical School in Boston, MA, decided to investigate whether umami foods could influence the brain to make more healthful choices when it comes to eating.
They built on previous studies suggesting that having an MSG-supplemented broth before a meal could decrease appetite — particularly in women at risk of overeating and weight gain.
"Previous research in humans studied the effects of umami broths on appetite, which is typically assessed with subjective measures," explains senior study author Dr. Miguel Alonso-Alonso.
"Here, we extended these findings replicating the beneficial effects of umami on healthy eating in women at higher risk of obesity, and we used new laboratory measures that are sensitive and objective."
Dr. Miguel Alonso-Alonso
The results of the new study have been published in the journal Neuropsychopharmacology.
Boosted inhibitory control
The team worked with healthy young women to understand how added MSG might influence the brain to make different dietary choices.
During a buffet meal, the participants were first asked to have a serving (240 milliliters) of chicken broth. The difference was that, for some, the broth was enriched with MSG (1.44 grams), whereas some had regular broth without MSG.
The scientists then evaluated how well each participant was able to control their eating behavior and measured brain activity as the women decided what they wanted to eat next.
In order to do this, the scientists asked the participants to complete a computer test assessing their inhibitory control, as well as to wear portable eye-tracking (which recorded eye movement) during the buffet meal. Additionally, the women's brains were scanned to track activity as they were choosing their meals.
Those who had consumed the umami broth had better inhibitory control, their gazes were more focused during the meal, and they had more activity in the left dorsolateral prefrontal cortex, which is a brain region associated with self-control during eating.
The scientists also saw that, among the cohort who had the MSG-enriched broth, the participants at a higher risk of obesity actually opted for foods with less saturated fat throughout their meals.
"Many cultures around the world advocate drinking a broth before a meal," says Dr. Alonso-Alonso, and, he adds, "[the new] study suggests the possibility that people at high risk of obesity could benefit from an umami-rich broth before a meal to facilitate healthy eating and healthy food choice."
Nevertheless, the study authors caution that their new findings would benefit from being supported by further research, analyzing the effects of umami foods on the brain in more detail.
"[H]ere we only evaluated immediate effects and in a laboratory context," Dr. Alonso-Alonso claims.
"Future research," he continues, "should address whether these observed changes can accumulate and affect food intake over time and/or whether they can be leveraged to help people lose weight more successfully."