That fifth-taste, the savory sensation known as umami, is making headlines once again.

Researchers at the University of Sussex performed a study that reached the following conclusion: eating a healthy, umami-rich breakfast may actually decrease your food cravings later in the day.

The study, which was funded by Ajinomoto North America, was published in full in the peer-reviewed American Journal of Clinical Nutrition.

Here’s a breakdown of the study:

The Theory

You may think you’re down with MSG (monosodium glutamate), which is the salty form of the amino acid known as glutamate. It’s a common flavor enhancer in Asian foods. Go to any Asian grocery store and you can buy some for your own home cooking.

For purposes of this study, researchers proposed that another amino acid-derived chemical called IMP (inosine-5′-monophosphate) may act in conjunction with MSG to both enhance flavor and promote a feeling of fullness or satiety.

The Test

The NHS reports that 27 participants were each given one bowl of carrot soup to eat, 45 minutes prior to lunch time.There were four possible bowls of soup that participants could eat: plain carrot soup (the control), carrot soup with added MSG and IMP, carrot soup with added protein and carbohydrate boosters, or carrot soup with protein, carbohydrate, MSG, and IMP together.

umami carrot soup

Photo: Flickr/Stuart Spivack

Prior to being given the soup, all participants had fasted from 11pm onward the night before the test was administered. They were then given a breakfast that consisted of a fixed portion of juice with a bowl of milk and cereal, then told to only drink water until they returned to perform the test three hours after finishing breakfast.

Before eating their bowls of soup, participants were given a survey to rate how alert, clear-headed, energetic, full, hungry, nauseous, and/or thirsty they felt. Then they ate their soup, and filled out another survey that asked the same questions again, as well as questions about how filling, pleasant, salty, savory, strong, and/or sweet the soup they had just eaten was. After 45 minutes passed, participants were asked to complete another survey about how they felt.

umami pasta

Photo: Flickr/Luca Nebuloni

Then a lunch that consisted of a 450g (nearly 1 pound) plate of pasta with sauce was served. Participants were asked to gauge their feelings after eating each 50g of pasta, and could continue eating until they felt full. The plates would be refilled once they had gotten down to only 50g left. Once lunch had concluded, participants filled out more surveys about their appetites and moods.

The Results

Two things happened: participants ate less pasta if they’d eaten the MSG and IMP-laced soups. Those who had eaten the soup that was higher in carbohydrate and protein also ate less pasta.

What about the soup that had both added carbohydrate and protein and MSG and IMP? That did best of all, with participants compensating better for their previous caloric intake (in the soup) when they ate their pasta lunch later.

Additionally, researchers found that participants experienced an immediate increase in appetite upon eating MSG and IMP-laced soup, but that this increase in hunger was only temporary. Participants also rated the soup’s “pleasantness” more highly when eating soup with MSG and IMP present.

What It All Means

Various publications, including The Daily Mail, have gone so far as to suggest that eating more umami may help control growing obesity problems throughout the industrialized world. But the NHS brought research firm Bazian on board to offer a full analysis of the study’s results.

Bazian cautions that this study only involved 27 participants—quite a small number, which limits the reliability of these results. The test was also extremely specific regarding foods eaten; not everyone will eat pasta directly following soup.

Furthermore, the company cautions that no studies regarding the benefit or harm of adding MSG or IMP to foods have yet been done.

Additional Considerations

While researchers did note that Ajinomoto North America “had no role in the study design, data collection, or analysis,” it’s also worth noting that the company produces both MSG and IMP, and that its parent company’s founder was none other than Professor Kikunae Ikeda, who discovered “umami” and how to create MSG in the first place.

Also, the New York Times just reported that researchers are now discovering that there may be a lot more to taste than just the five taste sensations (sweet, salty, bitter, sour, umami) with which we’ve all become familiar. Further research shows that we don’t just taste with our tongue; there are similar flavor receptors throughout our intestines, meaning much of what we taste and how we react to it may be unconscious.

Bottom line: there’s a lot going on with our perception of smell and taste that we still don’t understand.

[via the NHS, AJCN, the New York Times]

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