A recent study published in the Proceedings of the National Academy of Sciences (PNAS) suggests that individuals who frequently consume fried food may face a 12% increased risk of anxiety and a 7% increased risk of depression compared to those who do not eat fried food. This association was particularly significant for those who consume fried potatoes.
Depression and anxiety are two of the most common mental disorders, and individuals often experience both conditions simultaneously. Estimates suggest that the global population’s prevalence of anxiety and depression increased by approximately 27% following the COVID-19 pandemic in 2020.
The primary symptoms of depression include persistent feelings of sadness, hopelessness, and a lack of interest in activities, often accompanied by other physical and emotional symptoms. Anxiety is characterized by excessive and often irrational worry, fear, or uneasiness, which can manifest physically and interfere with daily functioning.
The exact causes of depression and anxiety remain unknown, but various genetic, biological, environmental, and psychological factors are believed to contribute. Recent studies have shown a link between diet and the risk of developing depression and anxiety, with the so-called Western diet, consisting of fried or processed foods, refined grains, sugary products, and beer, associated with a higher risk.
Frying is a popular cooking method used in both restaurants and homes. However, studies have demonstrated that the frying process can alter the nutrient composition of food and produce harmful chemicals. One such chemical is acrylamide, which is generated when frying carbohydrate-rich foods like potatoes. Epidemiological studies have linked prolonged acrylamide exposure to an increased risk of neurological disorders, obesity, metabolic syndrome, cardiovascular disease, and depression. Acrylamide is also neurotoxic at higher concentrations.
Considering acrylamide’s presence in fried food, study author Anli Wang and colleagues aimed to investigate the association between acrylamide intake and depression and anxiety on a large population sample. They hypothesized that high consumption of fried food, and therefore high exposure to acrylamide, would increase symptoms of depression and anxiety by causing dyslipidemia (abnormal lipid levels in the blood) and inflammation.
The research team analyzed data from 140,728 individuals in the UK Biobank, a comprehensive biomedical database and research initiative that collects detailed health and genetic data from half a million UK residents.
In addition, the researchers conducted an experiment on zebrafish, exposing them to varying concentrations of acrylamide for 180 days. They performed several tests to assess signs of depression and anxiety in the fish and collected brain samples for tissue analysis after euthanizing them.
The findings revealed that individuals who consumed at least one fried meal per day were typically younger, male, and smokers compared to those who did not consume fried foods. Over the 11-year follow-up period, 8,294 participants displayed symptoms of anxiety, while 12,735 exhibited signs of depression.
After accounting for participants’ age and gender, the analysis showed that individuals consuming fried foods had a slightly higher likelihood of experiencing anxiety (12% higher) and depression (7% higher). Specifically, the consumption of fried potatoes was associated with a 4% higher risk of anxiety symptoms and a 2% higher risk of depression.
The zebrafish experiment showed that fish exposed to acrylamide (0.5 mM) experienced a reduction in body mass and length. These fish also exhibited a preference for areas of dim light or darkness, a behavior analogous to human anxiety. The researchers observed additional anxiety and depression-like behaviors in the fish. Tissue analysis of these specimens indicated that acrylamide exposure disrupted their lipid metabolism and triggered an inflammatory response.
“Consistently, long-term exposure to acrylamide, a representative food processing contaminant in fried products, exacerbates scototaxis [preference for staying or moving towards areas of reduced light or darkness] and thigmotaxis [preference for contact or close proximity to surfaces, often as a means of seeking shelter or security], and further impairs exploration ability and sociality of adult zebrafish, showing anxiety- and depressive-like behaviors,” wrote the study authors.
This study contributes to the scientific understanding of the relationship between diet and mental health. However, it is important to note the study’s limitations. The observed effects were relatively small, and the study’s design does not allow for cause-and-effect conclusions to be drawn from the data collected on humans.
The study, titled “High fried food consumption impacts anxiety and depression due to lipid metabolism disturbance and neuroinflammation”, was conducted by Anli Wang, Xuzhi Wan, Pan Zhuang, Wei Jia, Yang Ao, Xiaohui Liu, Yimei Tian, Li Zhu, Yingyu Huang, Jianxin Yao, Binjie Wang, Yuanzhao Wu, Zhongshi Xu, Jiye Wang, Weixuan Yao, Jingjing Jiao, and Yu Zhang.
