In their study with laboratory
rats, Dr Beverly Muhlhausler, Postdoctoral Fellow in the University's FOODplus
Research Centre, and her colleagues, found that a junk food diet during
pregnancy and lactation desensitized the mesolimbic reward pathway (the reward
system in the brain) fuelled by these highly palatable foods.
'We found that the opioid
signalling pathway (the reward pathway) in these offspring was less sensitive
than those whose mothers were eating a standard diet,' Dr Muhlhausler says.
The opioid system plays a role in
energy-driven feeding as well as food hedonics resulting in a higher intake of
junk food and these are produced by the body as a reward response. Opioids
target the brain's reward system by flooding the circuit with dopamine, a 'feel
good' neurotransmitter that regulates feelings of pleasure
So, being addicted to junk food
is very similar to that of being addicted to drugs.
'In the same way that someone addicted to opioid drugs
has to consume more of the drug over time to achieve the same 'high',
continually producing excess opioids by eating too much junk food results in
the need to consume more foods full of fat and sugar to get the same
pleasurable sensation,' says Muhlhausler.
This study showed that babies
born to a mother who mostly ate junk food would need to eat more fat and sugar
to get the same good feeling
, because the opioid receptors in the babies
change making the reward system less sensitive thus increasing their preference
for junk food. These babies tend to grow up into high-fat, high-sugar food
junkies leading to health problems.
What this means is, mothers
eating a lot of junk food while pregnant are setting up their children to be
. Unfortunately, the alterations to the opioid receptors are
permanent found the researchers.
'It is important to try and understand the effects of the
maternal diet at a very early stage in the offspring to see what systems could
be targeted, if any, to reverse the problem,' Muhlhausler opined.
'Although our research shows that many of the
long-term health problems associated with maternal junk food diets can be
avoided if offspring carefully follow a healthy diet after weaning
are always going to have a predisposition for over-consumption of junk food and
obesity. It's going to make it much more difficult for them to maintain a
healthy body weight', she continued. 'The take-home message for women is
that eating large amounts of junk food during pregnancy and while breastfeeding
will have long-term consequences for their child's preference for these foods,
which will ultimately have negative effects on their health'