Eating carrots, kale and sweet potatoes could prevent dementia in older adults, new research suggests. Consuming the compounds that give plants and vegetables their vibrant colours can bolster brain functioning in older adults. Those who had lower levels of carotenoids in their system had to rely on more brain power to complete memory-orientated tasks, scientists found. The powerful compounds can be found in a range of colourful vegetables and are known to improve cognitive ability. Researchers from the University of Georgia used functional MRI technology to investigate how levels of carotenoids affect brain activity.