Maternal exposure to fatty food aromas predisposes offspring to obesity

A research team at the Max Planck Institute for Metabolism Research has found that the smell of fatty foods during pregnancy increases the risk of overweight and obesity in children. The researchers fed pregnant mice a healthy diet low in fat but containing fatty smells, such as the smell of bacon. The mothers themselves did not change their metabolism, but their offspring reacted more strongly to a high-fat diet and developed more pronounced obesity and insulin resistance, a sign of type 2 diabetes.

The researchers also found that the brains of the offspring had changed. The dopaminergic system, which plays an important role in motivation and reward, and the AgRP neurons, which control hunger and whole-body metabolism, reacted differently to high-fat food. 'The brains of the offspring resembled those of obese mice, simply because their mothers had eaten a healthy food that smelled like fatty food", explains Laura Casanueva Reimon, co-first author of the study.

The researchers found that fetuses are exposed to the smells of unhealthy foods while still in the womb and as newborns during breastfeeding through their mother's milk. Artificial activation of neural circuits associated with the smell of fatty foods during the neonatal period was sufficient to trigger obesity in adulthood.

What does this mean for humans?

It is known that children of overweight mothers have an increased risk of becoming overweight themselves. The study suggests that the mere smell of fatty food during development can increase the risk of overweight and obesity later in life, even in lean and healthy mothers. However, it is important to emphasize that in these experiments the mothers needed to ingest the food containing the fatty odors, as mere exposure to the smell alone did not lead to obesity in the offspring.

"What we discovered changes how we think a mother's diet can influence the health of her children," explains Sophie Steculorum, who led the study. "Until now, the focus has mostly been on maternal health and the negative effects of eating a high-fat diet, such as the risk of gaining too much weight. But our results suggest that the smells fetuses and newborns are exposed to could influence their health later in life independently of their mother's health."

Flavoring agents as food additives

The researchers used various flavouring agents to create the diets used for their investigations and found that these often contained the same ingredients that are used as food additives. One of this additive alone was able to trigger the same effects in the offspring. 'The findings point to the need for more research to understand how consuming these substances during pregnancy or breastfeeding could affect babies' development and metabolic health later in life", said Sophie Steculorum.