Mothers who eat junk food during pregnancy may
be condemning their children to crave the same diet, according
to animal tests.
Royal Veterinary College researchers found
that when pregnant rats were fed a diet of biscuits, crisps
and sweets, their babies ate more unhealthy food.
They said the British Journal of Nutrition
study showed the rats' behaviour was "programmed" in the womb.
Dieticians have stressed the importance of
a balanced diet for mothers-to-be.
Scientists have already shown that, in humans,
diet in early life can literally shape your future, setting
your risk of obesity and heart disease.
However, the latest research suggests that,
in rats at least, eating too much of the wrong food while carrying
a child could be potentially harmful.
Chow or sweets
The female rats used in the Wellcome Trust
funded research were either given a balanced diet of "rat chow"
- an unappealing but reasonably healthy diet - or access to
as many doughnuts, biscuits, muffins, sweets and crisps as they
This diet was continued in some rats up to
birth, and then during the breastfeeding period until weaning.
Unsurprisingly, the rats given free rein to
eat sweets consumed more food overall.
Significantly, however, their babies showed
marked differences in behaviour compared with the offspring
of chow-fed rats.
The young rats were split into different groups
- some of those from chow-fed mothers given nothing but their
chow to eat, while the babies of junk-fed mothers, and the rest
from chow-fed mothers, were given a mixture of chow and junk
food to see which they chose.
Those in the chow-only group consumed the least
food, while those from healthy-eating mothers given junk food
again were tempted to eat more.
However, the final group - babies of junk-food
mothers given the option of an unhealthy diet - ate the most
food, eating nine days worth of food for every seven days worth
consumed by the other babies on the junk food or chow menu.
They ate roughly twice as much as those on
the chow-only diets.
The researchers suggested that the "pleasure
chemicals" released by the mother when eating fatty foods might
have an effect on the developing brain of the foetus.
Professor Neil Stickland, who headed the research,
said: "The government is trying to encourage healthier eating
habits in school, but this shows that we need to start during
the foetal and suckling life.
"Future mothers should be aware that pregnancy
and lactation are not the time to over-indulge on fatty and
sugary treats on the assumption that they are 'eating for two'."
However, Fiona Ford, a research nutritionist
from the University of Sheffield, said that in the absence of
strong evidence that the same effect was present in humans,
it would be wrong to make women feel guilty about eating some
unhealthy snacks during pregnancy.
She said: "A balanced diet is important during
pregnancy. While this is interesting research, these mechanisms
are so finely tuned that I don't think we understand them yet."
Dr Atul Singham, from the Institute of Child
Health in London, also said that he was slightly sceptical about
the likely scale of "foetal programming" in child diet until
it could be proven in human studies.
He said: "This is what we are looking into
- but at the moment there is no data in humans to support this,
and obviously it is very difficult to carry out intervention
studies such as these in pregnancy."
Tracy Kelly, of the charity Diabetes UK, cautioned
against extrapolating to humans from studies on rats.
"Much more work needs to be done before we
draw any firm conclusions on how a junk food diet in pregnancy
can affect the baby?s craving for the same diet."