Eating junk food will cancel out all the positive effects of a healthy diet, a new study has suggested.
Researchers from Rush University Medical Center in Chicago said that those who indulge in regular cheat days are more at risk of having long-term health issues and cognitive decline, even if they adhere to the Mediterranean diet most of the time.
That particular diet is considered to be the healthiest by experts, as it includes plenty of fruit, grains, vegetables, olive oil, oily fish, and potatoes.
The team observed more than 5,000 adults over the age of 65 between 1993 and 2012, and asked them to fill in a cognitive assessment questionnaire, as well as completing a checklist of the different types of foods they had consumed, every three years.
Researchers looked at how closely each of the participants adhered to a Mediterranean diet, and also assessed how much each person followed a Western diet, which included fried foods, refined grains, sweets, processed meats, and full-fat dairy products.
They found that those who had a slower cognitive decline were those who stuck to the Mediterranean diet, and limited their consumption of junk food.
However, those who ate more junk food while on the Mediterranean diet had any of the beneficial effects of healthy food diminished.
Study leader Puja Agarwal explained findings showed that to benefit from the age-defying and health-boosting effects of the Mediterranean diet, people have to limit how much junk food they consume.
“Western diets may adversely affect cognitive health,” Agarwal said. “Individuals who had a high Mediterranean diet score compared to those who had the lowest score were equivalent to being 5.8 years younger in age cognitively.
“The more we can incorporate green leafy vegetables, other vegetables, berries, olive oil, and fish into our diets, the better it is for our aging brains and bodies.”