A new Australian study revealed that old people with unhealthy diets have smaller brain, ascertaining that junk food has an appalling impact on health.

ABC reported that the study showed alarming findings about the effects of unhealthy diet on a part of the brain called hippocampus -- also called as the bookcase or the filing cabinet of the brain which is critical for mood regulation and cognition.

The Victorian research covered about 250 people aged 60 to 64, in and around Canberra. Each of them took MRI scans to measure the size of the hippocampus.

"The hippocampus is absolutely central to learning and memory," Associate Professor Felice Jacka from Deakin University said. "Basically your hippocampus gets smaller as you age, and the difference we found between people with good diets and people with poor diets in terms of their left hippocampal volume, it counted for about 60 percent of that aged-related decline. So it's a not insubstantial amount."

Professor Felice, a Principal Research Fellow with the IMPACT Strategic Research Centre in Geelong, also stated the results of the study were more proof that a bad diet could cause mental problems. "It is becoming even clearer that diet is critically important to mental as well as physical health throughout life," adding, "The quality of people's diets is related to their risk for depression in particular."

Hippocampus is one of few structures in the brain which "continually grows new cells", which explicates why dietary intake is vital across all ages.

She admitted this is the first time they have seen the change in hippocampal function due to diet manipulation in humans. "And in the same way, the food that we put in our mouths needs to be of the best quality."

The researchers considered several other factors, such as gender, education, socioeconomic status, depression and blood pressure, Herald Sun informed. These factors were said to be related to both hippocampal volume and diet.

With these significant implications, Prof Felice then called for tougher restrictions on taxes and marketing on unhealthy food. She said examples of insalubrious food comprise "the usual suspects" -- high content of fat, sugar and salt.