How depressing? Junk food is bad for your mental health, study warns

Eating ultra-processed food significantly raises the risk of depression, according to a major study.

The foods have long been linked to medical conditions such as heart disease, cancer, diabetes and Alzheimer’s. 

But now researchers from Tehran University of Medical Sciences in Iran have concluded that regularly eating junk food raises the risk of depression by 15 per cent.

Diets which include ready meals, sugary cereals and soft drinks are often high in fat, salt and sugar, but low in vitamins and fibre. 

Using data from worldwide clinical trials and studies involving 160,000 men and women, the researchers looked for links between mental illness and poor diet.

Scientists suggest that ultra-processed foods (UPFs) could be triggering inflammation in the brain, leading to mental health problems

The results concluded that a high intake of nutrient-low meals also increased the risk of anxiety by 16 per cent.

Scientists suggest that ultra-processed foods (UPFs) could be triggering inflammation in the brain, leading to mental health problems.

At around 57 per cent of the national diet, Britons consume more UPFs than any other European country.

The Iranian study – the largest to date on the impact of diet on mental wellbeing – also suggested that these foods may lower levels of a protein called brain-derived neurotrophic factor in the body, which is crucial for healthy mental function.

However, some experts have argued that ultra-processed food might not necessarily trigger depression.

Instead, they argue that people who are depressed are more likely to make poor food choices.

‘When people feel down they often don’t make the effort to cook, so they turn to ready-made meals,’ says Gunter Kuhnle, professor of nutrition and food science at the University of Reading.

‘We’ve long known there is a strong relationship between diet and mental health, but it is difficult to definitively say that a bad diet causes depression.’

Earlier this year, the world’s largest review of UPFs found they increased the risk of harm to every part of the body when consumed in large quantities.

The study, published in the British Medical Journal, found that diets rich in UPF items raised the risk of dying from a heart attack or stroke by 50 per cent.