Even the thought of eating broccoli, kale and arugula makes many people pucker, but if you aim to eat healthier, science says to suck it up: simply adding more bitter vegetables to your diet will eventually change how they taste to you.
Nutrient-rich leafy greens develop bitter toxic compounds to deter predators and pests.
“Plants make these compounds to defend themselves,” said Ann-Marie Torregrossa, assistant professor at the Department of Psychology at the University of Buffalo, associate director of the Center of Ingestive Behavior Research. “Almost any green vegetable is going to have these compounds in them. Evolutionarily, we think bitter signifies toxins, but not all bitter is toxic to us.”
Torregrossa compared the human aversion to bitterness to a more universally beloved taste: sweetness.
“Evolutionarily speaking, sweet is almost always safe calories,” Torregrossa said. “We tend to be drawn to sweet and reject bitter. We have a combination or learned and innate responses to different taste stimuli.”
How our diets change the way we taste
Torregrossa was the lead author on a study conducted by scientists at the University of Buffalo which found that increasing the amount of bitter food you eat changes how bitter food tastes to you.
Earlier research showed that diet impacts the proteins in saliva, which is a key component to taste. The new research takes that one step further by connecting those changes in saliva to changes in taste.
The researchers gave one group of rats diets comprised primarily of quinine, a well-studied bitter compound, and another group diets of tannic acid, a bitter compound more likely to be found in human diets.
“We’re talking about compounds that activate bitter taste receptors,” Torregrossa said. “Quinine is not going to be found in your normal diet, [except] in gin and tonic. Tannic acid is in red wine, tea, nuts and bananas.”
In addition to a control group of rats without bitter diets, the fourth group of rats were fed sucrose octaacetate, an artificial, a modified sucrose compound that is designed to hit bitter taste buds instead of sweet.
The bitterness experiment
Before they started their diets, the rats were presented with a challenge: lick a plastic ball loaded with a certain concentration of a bitter solution, and if it tastes bitter, run to a port on the right. The researchers reduced concentration until the rats could not taste bitterness anymore and answered incorrectly.
After a few weeks, the rats with quinine and tannic acid diets failed the test miserably.
“They couldn’t tell [it was bitter] anymore, even though three weeks earlier, they were very good at tasting that compound as bitter,” Torregrossa said.
The group of rats fed the bitter sucrose octaacetate diet, however, were still able to taste bitterness and pass the test.
“There’s something different about the way that compound activates the receptors or the fact that it doesn’t have extra natural compounds,” Torregrossa said. “There might be something missing in it. It’s a really interesting problem.”
How to make bitter vegetables work for you
Torregrossa said that the time it takes to see effects from adding more bitter foods to your diet would vary in human subjects.
“In the animal study, it’s the only food they get,” Torregrossa said. “In humans, with a more variable diet, it’s sort of hard to estimate.”
Still, the results of the study suggest a new way to help people improve their diets. Torregrossa said that instead of telling dieters that bitter vegetables taste delicious, more honest, science-based advice would be more effective.
“If people are not hearing something that’s true to them, they’re less likely to comply with that advice,” Torregrossa explained. “Say, ‘I know this doesn’t taste good, but the more you eat it, the more accustomed you’ll get to it.’”
Torregrossa also hopes future research on bitterness will help solve issues of pediatric compliance, or getting infants and children to take life-saving medicines.
“Infants and young children don’t understand they need to take medication, they just know that it tastes bad,” Torregrossa said. “Maybe we can isolate compounds to reduce the bitterness of pediatric medicine.”
For now, the takeaway is this: if at first you don’t like broccoli, try, try again. Soon enough, you will be able to stomach it.