FRIED FOODS, ANXIETY AND DEPRESSION

Human-authored, evidence-based – 5 min read

Anxiety and depression are among the most common mental health disorders worldwide. At the same time, fried foods, now a staple of the Western diet, are becoming increasingly consumed globally. Previous research has linked higher intake of fried and processed and beer with an increased risk of both anxiety and depression. Despite this, relatively few studies have explored the potential role of acrylamide in mental health. Understanding this connection could help shape future public health strategies and dietary approaches aimed at supporting mental well-being. A newly published study has shed some light on the effects of acrylamide on anxiety and depression.

But first, what exactly is acrylamide?
Frying can alter the nutritional quality of foods and lead to the formation of potentially harmful compounds, such as acrylamide (fig 1). For instance, when carbohydrate-rich foods like potatoes are fried at high temperatures, especially during frying, roasting, or baking, the natural sugars react with an amino acid called asparagine as the food browns and becomes crisp creating acrylamide. Increased acrylamide exposures has been associated with obesity, metabolic dysfunction, and neurological issues.

The main chemical process that causes this is known as the Maillard Reaction; it is the same reaction that ‘browns’ food and affects its taste. It’s most commonly found in foods such as; chips, fries, toast, biscuits, and even coffee in smaller amounts. The reason it gets attention is because very high doses have shown harmful effects in animal studies, including potential nerve and cancer risks (3), although the relevance and significance of typical dietary acrylamide exposure in humans is still not fully elucidated. In simple terms, acrylamide is just a by-product of cooking certain foods too hot or for too long, especially when they become very brown or burnt. Most health advice focuses on moderation and avoiding over-browning rather than cutting these foods out completely.

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How was the study conducted?
The study published in Proceedings of the National Academy of Sciences (PNAS) used a two-part design combining large-scale human data with experimental validation on Zebrafish (1). First, the researchers analysed data from the UK Biobank, a large prospective cohort of over 140,000 participants. They assessed self-reported fried food consumption and followed individuals over time (around a decade) to examine whether higher intake was associated with the development of anxiety and depression. Statistical models were used to adjust for various confounding factors such as lifestyle, BMI, and socioeconomic variables, although residual confounding remained a limitation. Residual confounding is the lingering bias or error in research findings that remains even after researchers have attempted to control for known contributors (confounding factors).

To explore potential mechanisms behind this association, the researchers then conducted animal experiments using zebrafish. They exposed the fish to acrylamide, a compound formed during high-temperature frying, and observed behavioural changes consistent with anxiety-like states. They also performed molecular analyses on brain tissue, including transcriptomics, to investigate biological pathways. These experiments suggested that acrylamide exposure could disrupt lipid metabolism, increase oxidative stress, and trigger neuroinflammation, offering a possible mechanistic link.

What did the study show?
Overall, the researchers found that people who regularly consumed fried foods, especially fried potatoes like French fries, had a 12% higher risk of anxiety, as well as a 7% higher risk of depression when compared to people who didn’t eat fried foods. People who ate fried potatoes also had a 2% higher risk of depression than those who ate fried white meat, like fried chicken.

Is it just the acrylamide?
No! Advanced glycation end products (AGEs) are compounds that also form when sugars react non-enzymatically with proteins or fats, especially under conditions of high heat such as frying, grilling, roasting, and baking and also linked to increased anxiety and depression in animal models (2). Fried animal foods and potatoes, are one of the highest sources of AGEs. AGEs are also produced in the body as part of normal metabolism, but their accumulation can increase with aging, high blood sugar levels, and diets rich in heavily cooked or processed foods. Once formed, AGEs can alter the structure and function of proteins, making tissues less flexible and more prone to damage over time.

From a health perspective, AGEs are of interest because they can contribute to oxidative stress and inflammation. They interact with specific receptors in the body, often referred to as RAGE (receptor for advanced glycation end products), which can activate inflammatory pathways. This chronic low-grade inflammation has been linked in research to conditions such as cardiovascular disease (fig 2), insulin resistance, and complications associated with diabetes (3). Increased AGEs in processed foods is also linked to faster aging and worse skin (5).

Dietary AGEs, which come from foods cooked at high temperatures with dry heat, can add to the body’s overall burden, although the extent of their absorption and impact is still being studied. Foods like fried meats, baked goods, and fried potatoes tend to have higher AGE levels. Some research suggests that reducing dietary AGE intake may help lower markers of inflammation and oxidative stress (3), but the overall contribution of diet compared to internally produced AGEs remains an active area of scientific investigation. Ways to reduce AGEs formation is to use less aggressive cooking methods, such as boiling, steaming, poaching or sous vide (fig 3).

Overall, AGEs are considered one of several factors that may contribute to long-term tissue aging and chronic disease risk, particularly when combined with high blood sugar, oxidative stress, or inflammatory conditions. However, they are not inherently harmful in small amounts, and their effects depend on overall metabolic health, dietary patterns, and cooking methods.

What about cooking oils?
Furtheremore, cooking oils can also undergo a process called lipid peroxidation when they are heated, especially at high temperatures or when reused multiple times. This means the fats in the oil react with oxygen and break down into unstable compounds that can be harmful in large amounts causing inflammation. When foods cooked in these oils also contain advanced glycation end products (AGEs), the combination may have a kind of additive or ‘synergistic’ negative effect in the body, increasing oxidative stress and inflammation more than either alone. In simple terms, repeatedly heated or overheated oils can produce degraded fats that, together with compounds formed during high-heat cooking, may place extra strain on the body over time, particularly if consumed frequently. So in a nutshell, frying food can increase your exposure to acrylamide, AGEs and lipid peroxidation causing inflammation linked to a wide range of metabolic diseases and faster aging.

Conclusions
The evidence discussed highlights the perils of regularly consuming fried foods, at least with some form of regularity. The study combined observational epidemiology (human data) with experimental mechanistic work (animal model) to move from correlation toward a plausible biological reasoning and explanation, however, it still cannot prove causation in humans. The research nevertheless does appear to suggest that practicing caution and consuming less fried foods may be beneficial for health.

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