A recent study suggests that protein, not sugar, stimulates brains cells and neurons keeping us thin and awake. |
A
new study has found that protein and not sugar activates the cells
responsible for keeping us awake and burning calories. The research,
published this week in the scientific journal Neuron, has implications for understanding obesity and sleep disorders.
Wakefulness
and energy expenditure rely on “orexin cells”, which secrete a
stimulant called orexin/hypocretin in the brain. Reduced activity in
these unique cells results in narcolepsy and has been linked to weight
gain.
Scientists
at the University of Cambridge compared actions of different nutrients
on orexin cells. They found that amino acids—nutrients found in proteins
such as egg whites—stimulate orexin neurons much more than other
nutrients.
“Sleep
patterns, health, and body weight are intertwined. Shift work, as well
as poor diet, can lead to obesity,” said lead researcher Dr. Denis
Burdakov of the Department of Pharmacology and Institute of Metabolic
Science. “Electrical impulses emitted by orexin cells stimulate
wakefulness and tell the body to burn calories. We wondered whether
dietary nutrients alter those impulses.”
To
explore this, the scientists highlighted the orexin cells (which are
scarce and difficult to find) with genetically targeted fluorescence in
mouse brains. They then introduced different nutrients, such as amino
acid mixtures similar to egg whites, while tracking orexin cell
impulses.
They
discovered that amino acids stimulate orexin cells. Previous work by
the group found that glucose blocks orexin cells (which was cited as a
reason for after-meal sleepiness), and so the researchers also looked at
interactions between sugar and protein. They found that amino acids
stop glucose from blocking orexin cells (in other words, protein negated
the effects of sugar on the cells).
These
findings may shed light on previously unexplained observations showing
that protein meals can make people feel less calm and more alert than
carbohydrate meals.
“What
is exciting is to have a rational way to ‘tune’ select brain cells to
be more or less active by deciding what food to eat,” Dr Burdakov said.
“Not all brain cells are simply turned on by all nutrients, dietary
composition is critical.
“To
combat obesity and insomnia in today’s society, we need more
information on how diet affects sleep and appetite cells. For now,
research suggests that if you have a choice between jam on toast, or egg
whites on toast, go for the latter! Even though the two may contain the
same number of calories, having a bit of protein will tell the body to
burn more calories out of those consumed.”
Activation of Central Orexin/Hypocretin Neurons by Dietary Amino Acids
