The cognitive score of people in the study who ate the most flavonols declined 0.4 units per decade more slowly than those who ate the fewest flavonols.

"It's exciting that our study shows making specific diet choices may lead to a slower rate of cognitive decline," said study author Dr.

The study looked at the impact of the four major flavonols — kaempferol, quercetin, myricetin and isorhamnetin — on the rate of cognitive decline over the seven years.

The greatest impact was found with kaempferol: People who ate the highest amounts of foods with kaempferol showed a 0.4 units per decade slower rate of cognitive decline compared with those who ate the fewest, according to the study.

Myricetin was next: People who ate the most foods with myricetin had a 0.3 units per decade slower rate of cognitive decline compared with the lowest consuming group.

People who ate the most foods with quercetin showed a 0.2 units per decade slower rate of cognitive decline.

Despite the apparent positives, studies on the impact of flavonols on human health have been inconclusive — mainly because many are observational and cannot show a direct cause and effect.

A few randomized controlled trials — the scientific gold standard — have shown benefits associated with flavonols for controlling blood sugar in type 2 diabetes and improving cardiovascular health, according to the Linus Pauling Institute, home to the Micronutrient Information Center, an online database for nutrition information.