Prebiotics, although carbohydrates, are not the starchy or
sugary type of carbohydrates we typically think of; prebiotic carbohydrates occur naturally in many plants.
A 5 - year study
of 3,500 middle - aged adults published in the British Journal
of Psychiatry in 2009 showed that people who ate a diet high in processed foods, including refined
carbohydrates,
sugary desserts, fried foods and processed meats, had a 58 percent higher risk
of depression compared with those who followed a healthy Mediterranean -
type diet.