There is an old saying that you are what you eat. Many people believe this, and some have doubts about it, but what a well-known psychiatrist recently said will undoubtedly make you reconsider this long-held opinion.

Dr Daniel Amen, a brain-imaging researcher in California, has said that people who are fighting depression should stop eating junk food, which according to him is harmful for the patients.

"Your gut health is critical to brain health," Dr Daniel Amen said in a TikTok last week. "If you have, for example, an ultra-processed food diet, you have a dramatically increased risk of struggling with depression."

According to The New York Post, researchers have long been highlighting the importance of the gut-brain connection-the idea that the gut and brain constantly communicate through an intricate network of nerves and chemical signals. The brain signals the gut to prepare for food digestion, while stress can trigger signals that cause gastrointestinal symptoms like nausea or diarrhoea.

For its part, the gut microbiome - the collection of bacteria, viruses, and fungi in our digestive system - produces chemicals that can influence brain function and affect mood.

In his TikTok video, Dr Amen notes that over 100 trillion microbes, primarily bacteria, make up the microbiome. He refers to them as "bugs" and likens them to "pets."

"You have to feed your gut bugs healthy foods, fibre, colourful fruits and vegetables, and healthy protein in order for your gut to support your brain," Amen explained.

According to the National Institutes of Health, junk food can have many negative health effects, including obesity, type 2 diabetes, heart disease, digestive issues, high blood pressure, and depression.