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Lower satiety for
fructose vs glucose drinks
An article by Ben Bouckley, Edited by Dr.
Saleeby
Introducing their
research, Kathleen Page (Yale University School of Medicine) and colleagues
said that increases in fructose consumption
had shadowed rising obesity rates in the US, and that “high fructose diets are
thought to promote weight gain and insulin
resistance”.
The scientists found that
drinking a 75g pure glucose preparation alone, and not a 75g pure fructose
drink in isolation, reduced cerebral blood
flow and activity in brain regions regulating appetite.
Ingestion of glucose alone
produced increased ratings of satiety and fullness compared with fructose,
which is very rarely used on its own as a
beverage sweetener; high fructose corn syrup (HFCS) is processed to convert some of its glucose into fructose, to boost
sweetness levels.
In an accompanying JAMA
editorial, Jonathan Purnell and Damien Fair from Oregon Health & Science
University said the study supported the
“conceptual framework” linking fructose consumption to neurobiological pathway changes that promoted increased food intake. “The major new finding
reported by Page et al. is that the hypothalamic brain signal generated in
response to fructose ingestion was
statistically different from the response following glucose ingestion,” Purnell
and Fair wrote. “[A] difference was found and is
accompanied by an increased sensation of fullness and satiety after glucose,
but not fructose, consumption.”
Page et al. said that rat
studies showed that ‘central administration’ (injection into hypothalamus) of
fructose in rodents provoked feeding, Page et
al. said, while glucose promoted satiety. “Thus, fructose possibly increases food-seeking behavior and increases food intake”.
But the current study
authors admitted that no-one really understood the human implications of the
relation between brain regions and glucose- or
fructose- inspired animal feeding patterns. Examining neurophysiological factors
that could underlie associations between fructose consumption and weight gain, Page et al. recruited 20 healthy adults for
two magnetic resonance imaging sessions.
The team found a
significantly greater reduction in regional cerebral blood flow (CBF) in the
hypothalamic region of the brain after
glucose, rather than fructose, consumption. “Glucose but not fructose
ingestion reduced the activation of the hypothalamus, insula and striatum,
brain regions that regulate appetite,
motivation and reward processing,” Page et al. said.
“Glucose ingestion also
increased functional connections between the hypothalamic-striatal network and increased satiety.” The different responses to fructose
were associated with reduced systemic levels of satiety-signaling hormone insulin, the scientists added.
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