Mothers-to-be should avoid eating snacks that have been doused in vegetable oil, experts have once again warned.
Scientists fear linoleic acid, an omega-6 fat, could harm babies in the womb after they discovered it causes internal swelling in tests on rats.
They warned consuming too much of it may lead to ‘pregnancy complications and poor development of babies’.
Vegetable oil, often used to cook pizzas, potato-based snacks and bread, is one of the biggest sources of linoleic acid.
NHS guidance states mothers-to-be should have only small amounts of foods rich in unsaturated fat, such as vegetable oils.
Vegetable oil, often used for cooking pizzas, potato-based snacks and bread, is one of the biggest sources of linoleic acid
It also urges them to steer clear of fatty foods such as pizza and chips – but not because they contain linoleic acid.
Researchers based at Griffith University, Brisbane, gave rats a diet high in linoleic acid for 10 weeks.
They ate the equivalent of three times more than they should.
The American Heart Association says adults should consume between 100 and 200 calories from linoleic acid each day.
Linoleic acid is the predominant polyunsaturated fatty acid in the Western diet, according to researchers at Harvard University.
TIPS FOR A HEALTHY PREGNANCY
Pregnancy health charity Tommy’s gives a list of actions which would have a positive impact on the health of a pregnancy and the future child if done before the mother stops contraception.
Take folic acid
Taking 400mcg of folic acid daily from two months before stopping contraception can help protect babies from developing neural tube defects such as spina bifida.
Smoking during pregnancy causes 2,200 premature births, 5,000 miscarriages and 300 perinatal deaths per year in the UK.
Be a healthy weight
Being overweight before and during pregnancy increases the risk of potentially dangerous conditions such as pre-eclampsia and diabetes.
Eat healthy and be active
A healthy mother is more likely to give birth to a healthy baby, and both will help maintain a safe body weight.
Speak to your GP if you are taking medication
Some medications may affect pregnancy, and it is best to check with a GP as soon as possible
Dr Deanne Skelly and her colleagues then forced the rodents to mate and investigated the dangers of the diet on their offspring.
They searched for any changes inside the mothers and their babies, and examined levels of cholesterol and levels of inflammatory proteins – which cause dangerous swelling inside the body.
Results showed rats fed lots of linoleic acid gave birth to offspring with lower levels of hormones that regulate growth, suggesting they could have development problems.
However, there were no recorded differences in size when the young rats were killed after 20 days.
The rats also had more inflammatory proteins in the liver, according to the results published in The Journal of Physiology.
In a press release, the team said ‘these changes may result in an increased risk of pregnancy complications and poor development of the babies’.
Commenting on the research, Dr Skelly said: ‘It is important for pregnant women to consider their diet.’
She added the study is ‘yet another example’ consuming too much of a certain type of nutrient can have a negative impact on the growing baby.
Further trials are still needed to confirm the effects, the researchers said.
And they pointed out that when humans eat diets rich in linoleic acid, they also tend to be high in fat, sugar and salt.
Writing in the journal, the researchers said: ‘Dietary intakes of linoleic acid have increased dramatically in Western populations, including in women of reproductive age.
However, in the study, the only change in the diet was higher linoleic acid, but no changes in fat, sugar or salt.
The jury is currently out on linoleic acid. Research has linked it to inflammation – a bodily response thought to lead to chronic diseases.
While other studies have suggested consuming too much may increase the risk of heart disease, the world’s leading killer.
But Harvard Researchers found in 2014 that swapping saturated fat for linoleic acid actually lowers risk of coronary heart disease.
WHAT SHOULD A BALANCED DIET LOOK LIKE?
Meals should be based on potatoes, bread, rice, pasta or other starchy carbohydrates, ideally wholegrain, according to the NHS
• Eat at least 5 portions of a variety of fruit and vegetables every day. All fresh, frozen, dried and canned fruit and vegetables count
• Base meals on potatoes, bread, rice, pasta or other starchy carbohydrates, ideally wholegrain
• 30 grams of fibre a day: This is the same as eating all of the following: 5 portions of fruit and vegetables, 2 whole-wheat cereal biscuits, 2 thick slices of wholemeal bread and large baked potato with the skin on
• Have some dairy or dairy alternatives (such as soya drinks) choosing lower fat and lower sugar options
• Eat some beans, pulses, fish, eggs, meat and other proteins (including 2 portions of fish every week, one of which should be oily)
• Choose unsaturated oils and spreads and consuming in small amounts
• Drink 6-8 cups/glasses of water a day
• Adults should have less than 6g of salt and 20g of saturated fat for women or 30g for men a day
Source: NHS Eatwell Guide