April 24, 2023

expert reaction to study on fried foods and anxiety and depression

A study published in PNAS looks at fried food consumption and anxiety and depression.

Prof Gunter Kuhnle, Professor of Nutrition and Food Science, University of Reading, said:

“This study investigated whether there is an association between the consumption of fried foods and mental health. The authors used a two-pronged approach: first investigating whether there is an association in humans and then whether their hypothesis works in Zebrafish.

“They compared intake of fried food in the UK Biobank cohort with the development of anxiety or depression over a period of about ten years and found that fried food intake was associated with an increased risk of anxiety. However, those who consumed fried food where also more likely to be active smokers, have a higher body mass index and were more likely to have lower income and a lower educational background; factors that are likely affecting mental health and that cannot be completely excluded in the analyses they conducted. Interestingly, they only appear to have found an association for certain fried foods but not all those investigated. They report an association with fried potatoes and white meat, but not fish, even though fried fish as part of fish & chips is likely an important contributor to fried food intake (and an important source of oily fish!).

“The study in Zebrafish is interesting, but it is not clear how well these results can be translated into humans. A key difference is that the study uses long-term continuous exposure – something that is unlikely to happen to humans as we do not tend to eat fried food continuously. This makes it very difficult to compare the amounts used – but the lowest concentration used in this study (71 mg/L) is clearly much higher than even very high reported acrylamide concentrations (e.g. American crisps with up to 2.3 mg/kg) – the average crisps have much less acrylamide (~0.4 mg/kg).

“However, it is not clear why the authors focused exclusively on acrylamide, as many other pathways could be considered that link fried food intake with mental health – but the epidemiology data does not really suggest that there is a strong link.

“In summary, the study does not provide any data suggesting that there is a link between fried food intake and mental health, and it is not suitable to provide any information about the effect of acrylamide in humans as the amounts used are too high.”

Dr Duane Mellor, Registered Dietitian and Senior Lecturer, Aston Medical School, Aston University, said:

“This is an interesting study which attempts to link data from the UK Biobank which suggested there was an association between individuals reporting anxiety and depressive symptoms and intake of fried foods, especially fried potatoes. However, to link this to acrylamide using detailed studies in zebrafish, which expressed anxiety-like behaviours was potentially flawed. As although acrylamide is formed in fried foods like chips, crisps and fries it is also produced by baking and toasting so toasted bread and roasted coffee are also significant sources of this compound which has previously been associated with an increased risk of cancer.

“It is possible that people who consume more fried foods may have other risk factors which increase their risk of mental health problems, which although income and education were considered, other factors which could contribute to mental health issues could mean there is either reverse causality or considerable confounding factors which were not accounted for.

“Overall this study does not change the evidence that a healthy diet which is based on plenty of vegetables, fruit, nuts, seeds, pulses and moderate amounts of other foods is associated with better mental and physical health, and caution should be used when using animal models which only show ‘anxiety-like’ symptoms and especially when using a compound to induce these which is not unique to fried food.”

‘High fried food consumption impacts anxiety and depression due to lipid metabolism disturbance and neuroinflammation’ by Anli Wang et al. was published in PNAS at 20:00 UK time on Monday 24^th April.

DOI: https://doi.org/10.1073/pnas.2221097120

Declared interests

Prof Gunter Kuhnle: “No COI.”

Dr Duane Mellor: “No conflicts of interest.”