Consumption of a high fat, high sugar, Western style diet leads to the long-term impairment of brain functioning and may contribute to the development of neurodegenerative conditions, say scientists reviewing decades of evidence.
The suggestions come from work carried out by Heather Francis and her colleagues at Macquarie University, Australia, who also warn there is limited evidence to suggest that such changes to brain functions can be reversed.
“It is now widely agreed that there has been a rise in obesity levels in Western societies over the past 30 years,” said the researchers. “It is therefore clearly important to understand how the foods that make us fat also act to impair cognition and affect, and whether and how these impairments can further dysregulate appetitive control in humans.”
Reviewing the evidence from animal and human studies in addition to epidemiological data from the last three decades, the Australian researchers provide an overview of how a Western diet that is high in saturated fats and refined sugars (HFS diet) causes alterations to speciﬁc brain regions thought to underlie impairments in two key aspects of neurological function: cognitive abilities (in particular episodic memory, attention and inhibition) and reward processes.
“While human research data is still at an early stage, there is evidence of an association between HFS diet and impaired cognitive function,” said the authors. “Based upon the animal data, and a growing understanding of how HFS diets can disrupt brain function, we further suggest that there is a causal link running from HFS diet to impaired brain function in humans, and that HFS diets also contribute to the development of neurodegenerative conditions.”
The new review examined the evidence for the HFS diet leading to damage in brain systems from human data, “using converging lines of evidence from neuropsychological, epidemiological and neuroimaging data.”
In doing so, the researchers highlight several long-term brain-related costs of consuming a HFS diet.
“It appears that an HFS diet can lead to changes in brain regions associated with energy regulation and the affective appraisal of food.”
The team also suggested that HFS diets are also starting to be viewed as possible contributing factors to the onset of ADHD and certain neurodegenerative diseases.
“These forms of neural dysfunction result in impaired social, educational and occupational function, and present a substantial burden on the social-welfare system, especially AD.”
“Understanding the role of diet in these diseases is clearly important as a tool for prevention, but also in determining their cause,” said Francis and her colleagues. “Especially with the interesting conceptualization of AD as representing a ‘diabetes of the brain’.”
Published online ahead of print, doi: 10.1016/j.appet.2012.12.018
“The longer-term impacts of Western diet on human cognition and the brain”
Authors: Heather Francis , Richard Stevenson