Combining the drink with exercise strengthens certain regions of the brain, making it appear more youthful and potentially preventing the organ's decline.
This finding could help people who are at risk of brain deterioration to remain functionally independent, such as those with a family history of dementia.
Beetroot juice's power likely lies in its nitric oxide content, which both increases blood flow to the brain and improves exercise performance.
Study author Professor Jack Rejeski, said: 'Nitric oxide is a really powerful molecule. It goes to the areas of the body which are hypoxic, or needing oxygen, and the brain is a heavy feeder of oxygen in your body.
'Compared to exercise alone, adding a beetroot juice supplement to exercise resulted in brain connectivity that closely resembles what you see in younger adults.'
Scientists from Wake Forest University, North Carolina, studied 26 men and women aged 55 and older who did not exercise and had high blood pressure.
Some participants were given beetroot juice one hour before walking for 50 minutes on a treadmill, while others did the same exercise but without the drink. This was repeated three times a week for six weeks.
Those who drank the juice had healthier brains, including the regions involved in movement, emotion and cognitive function.
The scientists also found higher levels of nitrate and nitrite in those who drank the juice.
Beetroot contains nitrate, which is first converted to nitrite and then nitric oxide in the body.
This comes after researchers from Queen Mary University of London found one daily glass of 250ml beetroot juice substantially lowers blood pressure.