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'High-fat' (Omega-6-rich, Omega-3 deficient) maternal diet can cause life-long changes in the fetal brain

Medical University of Vienna


When pregnant women consume diets high in polyunsaturated omega-6 fatty acids, an excess of endocannabinoids is produced which overloads the fetus, and impairs healthy brain development.


We've modified the title of this (otherwise pretty good) news article from Neuroscience News, as:

  1. Using the term 'High-Fat' to describe ANY kind of diet is so vague as to be useless - because there are many different kinds of fats, each with very different effects on health
  2. as used here, that term seems particularly misleading, given that the effects found relate specifically to the high omega-6 polyunsaturated fat (PUFA) content of the study diet (as the article itself does at least mention, and explain fairly well)
Calling it a 'high fat diet' in the headline (as so many articles always do) effectively conceals the fact that the effects found were the direct result of the excess of omega-6 relative to omega-3 PUFA - which is a key characteristic of typical modern, western-type diets.

It is these fats from which a whole array of different 'endocannabinoids' are made - and different ones are made from omega-6 fats, than from omega-3.

The effects shown involved lifelong impairments of brain function in the offspring of (animal) mothers eating this omega-6 rich (and therefore relatively omega-3 deficient) diet. 

Specifically - as already shown by previous research, the endocannabinoid-mediated effects of this omega-6/3 imbalance on the developing offspring's brain lead to:

  • permanent changes in brain networks, leading to an irreversible increase in anxiety and emotional dysregulation - and what's more
  • these kinds of brain changes are already known to raise risks for many developmental and psychiatric disorders, incuding not just anxiety, but ADHD, depression and schizophrenia.

Rather concerning is that this kind of diet is now eaten by most humans in all developed - and most developing - countries. 

It seems highly unlikely that most pregnant women would actually want to confer permanent brain changes of this kind on their unborn children - permanently raising their risks of anxiety, depression and many other emotional, behavioural and mental health problems.   

So it's very hard not to conclude that if most mothers-to-be actually knew that the diet they are eating could have these kinds of effects on their child's brain development - they would probably be willing to try to make different dietary choices.

Unfortunately, lazy and misleading headlines like this one (along with hundreds of thousands of similar ones over the years) imply that 'high fat' diets (type of fat unspecified) are the problem, so that girls and women of childbearing age have simply NOT been getting the information they really need. 

If they only knew the real facts - most mothers-to-be would probably be willing to consume a diet providing a healthier balance of fats to support their baby's brain development:

  • more omega-3 from fish and seafood - by far the best source of the long-chain omega-3 fats (EPA and DHA) needed for healthy brain development, and numerous other critical brain nutrients too, such as iodine, zinc, selenium, Vitamin D, and important B vitamins
  • less of the short-chain omega-6 PUFA (LA) from industrially produced seed oils (found in almost all processed foods - and usually called 'vegetable' oils to make them sound healthier...)

As it is, however - because of endless bad and misleading headlines like this one - most women instead still believe that foods and diets promoted or labelled as 'low fat' must be the healthier options. WRONG! The brain is 60% fat - and it really does matter what kind of fat it is made from.  

Ironically enough, the foods labelled 'low fat' are usually ultra-processed, high in sugar and refined carbohydrates, and undesirable artiifical additives - and with what fats they do contain coming from cheap 'vegetable' oils - rich in short-chain omega-6, and lacking omega-3.

In animals, as this latest study confirms, eating this kind of diet during pregnancy has permanent negative effects on brain development of the offspring, raising their lifelong risks for a wide range of emotional and mental health problems.

Obviously, similarly controlled studies in humans are just not possible, for both ethical and practical reasons - and findings in animals do not always generalise to humans.

However, the findings from animal studies like this one are entirely consistent with the increasing rates of mental health disorders that have now been observed for over 50 years in each successive generation of human children, adolescents and young adults whose mothers ate modern, western-type so-called 'high fat' (and high sugar) diets - i.e. omega-6-rich, omega-3 deficient diets - during their pregnancy.

For details of this research, see:

The same research is also covered in this news article (for which again, we have modified the title to make it more accurate):

And for previous research showing similar findings - in fact the first study to show permanent brain changes induced by omega-3 deficient (omega-6-rich) diets during pregnancy via endocannabinoid mechanisms, see also:

18th November 2019 - Neuroscience News


A study team at MedUni Vienna’s Center for Brain Research has found that high-fat maternal diets can cause life-long changes in the brain of the unborn offspring.

When a pregnant woman consumes a diet high in polyunsaturated omega-6 fatty acids, her body produces an excess of endogenous cannabinoids (endocannabinoids), which overload the fetal organism and impair the development of healthy brain networks.

Such a mechanism seems relevant to pathologies such as ADHD, schizophrenia and anxiety disorders. It is unlikely that such damage can simply be reversed by a subsequent change of diet.

The study, which has been published in the journal ‘Molecular Psychiatry’, examined in cell- and mouse models, how intake of high-fat diets throughout pregnancy (rich in polyunsaturated omega-6 fatty acids) impacts fetal brain development.

When the mother consumes a high-fat diet during pregnancy, both mother and child produce an excess of endocannabinoids, which can even be transferred from the mother to the fetus. Endocannabinoids can then overload the corresponding cannabinoid receptors in the fetal brain and limit their ability to signal. As a result, nerve cells will no longer be able to correctly integrate into the brain to fulfil their prospective functions.

The study also shows that these impairments persist throughout life of the affected offspring and can serve as critical triggers to developing psychiatric disorders later in life.

Endocannabinoids are substances produced by the body itself. They are part of the endocannabinoid system, which serves as a fundamental communication system in the brain as well as other organs. In the adult brain, endocannabinoids limit communication (‘chemical neurotransmission’) between neurons by binding to cannabinoid receptors.

In the developing brain, endocannabinoids determine when and where neurons are positioned and if they form connections with each other. This means that any substance that influences either endocannabinoid levels or directly affects cannabinoid receptor function will inevitably impinge upon brain development.

“By acting like a ‘stop signal’, a prolonged overload of endocannabinoids impairs the developmental program of many neurons in the fetal brain,” explains principal investigator Tibor Harkany, Head of the Department of Molecular Neurobiology at MedUni Vienna’s Center for Brain Research.

“Persistently muting cannabinoid receptors, we believe, alters the epigenetic programs of affected nerve cells. Epigenetic mechanisms determine the pattern of gene expression in any cell. If damaged, the cells are no longer able to carry out their functions adequately. This will limit their ability to adapt their proper shape or select communication partners because of a shortage of proteins required as cellular building blocks or signalling molecules.”

On a large scale, an inhibition to the creation of connections between brain cells will impair the formation of important neuronal networks, the functional building blocks of the brain. This can result in psychiatric disorders such as ADHD, schizophrenia and anxiety disorders.

The study also shows that these impairments persist throughout life of the affected offspring and can serve as critical triggers to developing psychiatric disorders later in life. The image is in the public domain.

Damage is likely irreversible

“As far as we can tell, the pathological changes of nerve cells we have found are irreversible,” explains Harkany. “It is of limited use to changing to a healthy, low-fat diet after birth when the damage has already been done.”

Although the study is based on animal models, Harkany stresses that other studies already indicate harmful effects in humans, while this report identifies the very molecular mechanisms that can also apply to humans.

Is treatment still possible?

“In order to find effective treatments, we will need active agents that directly intervene in the epigenetic regulation of gene expression,” explains lead author Valentina Cinquina. “We have not yet trialed any such drugs but it is an exciting prospect to work on such interventions, which can perhaps be used safely and effectively in the future.” For example, so-called histone deacytylase Inhibitors (HDACs) are extensively tested for their treatment potential in Alzheimer’s disease and various cancers.