Eating a diet high in fat and sugar during pregnancy changes the development of the opioid signally pathway in the baby’s brain and permanently alters the way this system operates after birth, according to new research from the University of Adelaide. Meanwhile, US research also shows the link between ‘feel good’ brain chemical dopamine and suggests obesity be classified as an “addictive disorder”.

Mother’s diet changes brain chemistry of offspring

The Australian animal study, which was presented at the Annual Meeting of the Society for the Study of Ingestive Behaviour held in New Orleans 30 July 2013 to 2 August 2013, found that the gene encoding one of the key endogenous opiods, enkephalin, was expressed at a higher level in the offspring of rat mothers who consumed a diet high in fat and sugar compared with the offspring of mothers who ate standard rat feed.

The researchers said this increase in enkephalin, together previous work done by the group showing that an opioid receptor blocker was less effective at reducing fat and sugar intake in the pups of the “junk-food” fed mothers, shows for the first time that the opioid signalling pathway is less sensitive in “junk-food” exposed offspring.

Opioids are chemicals that are released when foods that are high in fat and sugar are consumed. These chemicals are responsible for causing the release of another ‘feel good’ chemical, dopamine.

Researchers said being less sensitive to opiods means that individuals whose mothers eat excessive quantities of food high in fat and sugar during pregnancy and breastfeeding would have to eat more of these foods to get the same ‘feel good’ response. This could make them more likely to over-consume these types of foods, according to the researchers.

“The results of this study will eventually permit us to better inform pregnant women about the enduring effect their diet has on the development of their child’s lifelong food preferences and risk of negative metabolic outcomes,” said Jessica Gugusheff, from the FoodPlus research centre at the University of Adelaide and lead author of the study.

US research suggests obesity could be an ‘addictive disorder’

Meanwhile, researchers from Tufts University in Massachusetts, have also found that there is a strong link between dopamine levels and obesity, suggesting that “common dietary obesity is an addictive disorder”.

A literature review published in August 2012 by Dr Emmanuel N. Pothos PhD and colleagues at the Tufts University School of Medicine found that brain chemistry responds similarly to food and to illicit drugs.

“Neurobiological studies have shown that the hedonic brain pathways activated by palatable food overlap considerably with those activated by drugs of abuse and suffer significant deficits after chronic exposure to high-energy diets,” Dr Pothos and colleagues wrote.

In their ongoing research, Dr Pothos and colleagues have found that dopamine release in rats kept on a high-fat diet for several weeks was depressed by 60 per cent with a consequent weight gain of at least 20 per cent. That is, the rats became dopamine deficient, which meant it was necessary to consume more in order to bring the brain’s chemistry back to homeostasis.

“Therefore, even without any diet history, genetic predisposition to obesity is characterised by depression of mesolimbic dopamine neurotransmission at a very early age; while genetic predisposition to obesity resistance is characterised by upregulation of mesolimbic dopamine neurotransmission,” the researchers said.

“The current food environment encourages these addictive-like behaviours where increased exposure through advertisements, proximity and increased portion sizes are all routine,” the researcher said.

Dr Pothos and colleagues have called for the reclassification of common dietary obesity as an addictive disorder, which they said “would necessitate policy changes”.

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