A new study out of Spain has showed that, in a sample of breastfeeding mothers, all of the women sampled had levels of acrylamide in their urine, a compound that is potentially seriously toxic and could be transferred to their children through their breastmilk.

Acrylamide is an organic compound that is classified as highly likely to be carcinogenic to humans. It’s carcinogenicity has already been demonstrated in rodent studies. It is mainly found in tobacco smoke and processed foods that are rich in carbohydrates and amino acids.

The cooking method, and the use of particular kinds of fat, affects the levels of this substance. Potatoes, for example, if cooked in low humidity conditions and above 120 degrees C (by baking, frying or roasting, for instance), produce high levels of acrylamide.

Acrylamide: a potentially carcinogenic chemical


The study was carried out with urine samples from 120 breastfeeding women between the ages of 20 and 45 who gave birth in the Hospital Universitari i Politènic La Fe of Valencia.

The study is part of the broader the BioMoVal project, whose objective is to determine the exposure of the adult population of the Valencian Community to food and environmental contaminants.

The results showed that all of the mothers had been exposed to acrylamide. It is known that the substance can be transferred from mothers to their babies through the consumption of the mother’s breast milk.

Although acrylamide’s relationship with cancer in humans has not been definitively proven, a number of studies indicate that it almost certainly has negative effects on children’s development. Exposure to prenatal acrylamide has been shown, for instance, to lead to higher levels of obesity and overweight among children.

In addition, the new study shows that the exposure and risk of the population studied is greater than the exposure observed in the adult population in other European studies. “The causes may be related to the different dietary guidelines, although further studies are required to gain greater certainty,” said Sandra Fernández, one of the lead researchers.

The type of fat used to cook food is known to be a significant determinant of how much acrylamide is produced and therefore ingested. Interestingly, this isn’t something the study authors mention, but it absolutely deserves mention because of how widely the worst kinds of oils – the ones that produce the most acrylamide – are consumed.

Vegetable oil, which we’ve called “one of the worst things you can eat“, is known to produce significantly more acrylamide that when heated than animal fats, as demonstrated in scientific studies.

One study notes that, “Significantly less acrylamide was produced in saturated animal fat than in unsaturated cooking oil, with 366 ng/g in lard and 211 ng/g in ghee versus 2447 ng/g in soy oil, followed by palm olein with 1442 ng/g.”

Vegetable oils are absolutely ubiquitous in the modern world, as the result of a determined campaign since the 1950s to substitute them for supposedly “unhealthy” animal fats. The effects of this substitution have been nothing short of disastrous (see the box below, for instance).

Soybean oil, the most commonly consumed oil in the US, causes significant weight gain, genetic dysregulation and neurological problems in mice

soybean oil

According to a 2020 study, soybean oil — the most commonly consumed oil in America — caused gene dysregulation in mice which led to neurological problems, particularly in their ability to bond, and weight gain.

Four groups of mice were fed different isocaloric diets (diets with the same number of calories). One group was fed a diet that contained conventional soybean oil, high in linoleic acid; the second, a diet that contained genetically modified soybean oil that was low in linoleic acid; the third, a diet that contained coconut oil, which is high in saturated fat; the fourth was given a low-fat control diet.

The researchers noted that the two soybean diets had similar but non-identical effects on expression of genes for the hypothalamus, whereas the coconut oil had a negligible effect compared to the control diet. 

Among the genes that were negatively altered by the soybean-oil diets were genes associated with inflammation, neuro-endocrine, neurochemical, and insulin signalling, as well as the production of oxytocin, an important hormone.

As the Twitter poster above (Carnivore Aurelius) noted, oxytocin plays an important role in empathy and social bonding, as well as other important biological processes including weight gain. Many of the genes that were dysregulated by the soybean oils are also linked to serious neurological diseases including Alheimer’s disease, Parkinson’s and autism.

Insulin resistance, a topic we have covered in two articles (here and here), was increased by the soybean diets, and the mice on the conventional soybean oil experienced the greatest amount of weight gain, despite consuming the same amount of calories as the others.

All in all, it looks like soybean oil is bad news indeed.

The new study is further evidence for our contention that you should avoid like the plague all so-called “healthy” vegetable oils and return instead to the animal products, like butter, lard and tallow, that have sustained humanity since time immemorial. The old ways really are the best.