With bitter foods, what you eat determines what you
like to eat
University
at Buffalo
Introducing
plant-based foods to a diet is a common-sense approach to healthy eating, but
many people don't like the taste of vegetables, bitter greens, in particular.
But
give that broccoli a chance.
Doing
so won't just change your mind; it will actually change the taste of those
foods, according to a new University at Buffalo study.
What
sounds at first like a culinary parlor trick is actually a scientific matter
based on specific proteins found in saliva. These proteins affect the sense of
taste, and diet composition, at least in part, determines those proteins.
Saliva
is a complex fluid containing around 1,000 specific proteins. Identifying all
the players is a work in progress, but everything we eat is dissolved in saliva
before it interacts with taste receptor cells and all these proteins are
candidates for influencing stimuli before food is tasted.
"What you eat creates the signature in your salivary proteome, and those proteins modulate your sense of taste," says Ann-Marie Torregrossa, an assistant professor in UB's Department of Psychology and the associate director of the university's Center for Ingestive Behavior Research, a comprehensive research home for studying eating and drinking behavior, obesity and other factors contributing to the daily decisions people make related to food and fluid intake.
"We've
shown in previous work with rats that changing your diet changes what proteins
are in your saliva. Now we're showing that the proteins in your saliva change
how you taste."
The
findings, published in the journal Chemical Senses, have
applications ranging from the obesity crisis to medical compliance.
"If
we can convince people to try broccoli, greens and bitter foods, they should
know that with repeated exposure, they'll taste better once they regulate these
proteins," says Torregrossa.
How
much repeated exposure? Give me a number.
"Our
data doesn't provide a number, such as 12 servings of broccoli, however, for
people who avoid these foods because of their bitterness, but would like to
include them in their diet, they should know their taste will eventually
change."
Bitterness
is also a near-universal characteristic of many pediatric medicines, and
getting infants to swallow a bitter liquid -- which by nature they want to
reject -- can be a challenge.
"An
additive to that medicine to make it less bitter would increase compliance,"
she says. "It's similar to liquid dietary supplements in the geriatric
population, which often contain sugar to tame the bitterness. Achieving the
same result without sweeteners has obvious benefits."
At
a bare minimum, Torregrossa says health care and nutritional professionals can
counsel people to explain the role of these salivary proteins.
"Trying
to convince someone that a salad tastes great isn't going to work because to
that person it doesn't taste great. Understanding with taste that we're dealing
with something that's moveable is significant."
Think
of this in an evolutionary context.
Bitter
foods, for foragers, can serve as a sign of danger, but it's an unreliable
predictor. Why look for another food source if there's something safe and abundant
at hand?
"Instead
of having the cognitive load of learning that a food is safe and having to
maintain that memory, instead you know that eventually this bitter food will
taste good," says Torregrossa. "It's an elegant physiological shift
allowing you to put these foods into your diet."
For
the study, Torregrossa trained to rats to choose from one of two water bottles
after tasting a solution, to indicate whether it tasted bitter. Animal research
in this case allows for tighter dietary control and the variation of specific
proteins can be monitored in a way that's difficult to achieve with human
participants.
"This
is interesting because we're not asking, 'Do you like this?' we're looking only
at 'Can you taste this as bitter?'" she says. "Animals with these
bitter-induced salivary proteins turned on cannot taste the bitterness at
higher concentrations than animals who do not have the same protein activated.
"Once
these proteins are on board the bitter tastes like water. It's gone."
Torregrossa's
work is an intriguing tactic in the obesity fight which sees many battles
focusing on over-consumption of high-fat and high-sugar foods.
"The
variation around sweets is very small," she says. "Nearly everyone
likes a cupcake, but the variation around liking broccoli is enormous.
"This
research helps explain why that variation with bitter food exists and how we
can get more people to eat broccoli instead of cupcakes."
