DRESDEN, Germany — “An apple a day keeps the doctor away,” especially when to comes to fighting off dementia. An international study finds the famously healthy fruit is rich in chemicals that fuel neurons, improving learning and memory.

Experiments on mice discovered grey matter increased after they were injected with phytonutrients, like flavonoids, which are abundant in fruits and vegetables. The effects were similar to those seen after exercise, which can also boost brain function.

Corresponding author Professor Gerd Kempermann from the German Center for Neurodegenerative Diseases says these dietary compounds are “vital for maintaining cognitive function.”

“They can have positive effects on different parts of the body – including the brain,” Kempermann says in a statement to SWNS.

How do these substances boost the brain?

These antioxidants dampen inflammation and strengthen the immune system. Researchers took stem cells from the brains of lab rodents and cultured them in petri dishes. After adding apple extracts like quercetin or DHBA (dihydroxybezoic acid), more neurons grew and fewer died.

Hippocampal precursor cells
Hippocampal precursor cells differentiate into neurons when treated with the apple-derived compound DHBA. (Credit: German Centre for Neurodegenerative Diseases)

“High concentrations of phytonutrients from apples stimulate the generation of new neurons – a process called neurogenesis,” Kempermann explains.

The results, published in Stem Cell Reports, were then confirmed in trials involving actual mice. Stem cells multiplied and produced more neurons after the scientists added in high doses of quercetin or DHBA.

Specifically, this applied to distinct structures in the adult brain including the hippocampus, vital for memory, learning, and navigation.

Apples contain pro-neurogenic compounds in both their peel and their flesh,” study authors write in their report.

Quercetin resides in the apple’s peel. The pigment adds color to the fruit and belongs to the flavonoid family. DHBA is a natural preservative unrelated to flavonoids. It is responsible for giving fruit its distinctive aroma. Both chemicals act in similar ways however, protecting cells by destroying harmful free radicals.

“‘An apple a day keeps the doctor away.’ There may be some truth to this aphorism,” researchers write. “Apart from being a source of energy, food is known to influence an individual’s overall fitness. A growing number of studies have demonstrated the health benefits of phytochemicals, the chemical substances found in plants.”

Finding ways to stop disease in our food?

apples antioxidants
(Credit: Apple Peel and Flesh Contain Pro-neurogenic Compounds – Stem Cell Reports)

These substances include resveratrol in red grapes and EGCG (epigallo-catechin-3-gallate) in green tea. Previous studies find they have a link to reducing the risk of diseases like cancer, heart disease, and dementia. Researchers believe quercetin and DHBA act in combination to promote neurogenesis and brain function when consumed in high amounts.

“The effects were comparable to those seen after physical exercise – a known stimulus for neurogenesis,” Kempermann tells SWNS.

When the mice received apple juice however, study authors say there was no benefit to brain health as it contains smaller quantities of the beneficial ingredients. The findings could have implications for protecting against Alzheimer’s disease. With no cure in sight for the degenerative condition, there is an increased focus on lifestyle factors that can help stop or delay its onset.

“As mammals evolved with exposure to particular diets, naturally abundant compounds may have become part of the set of environmental co-determinants that shaped brain structure and function,” study authors write.

“Future studies will be required to determine if these and other phytonutrients can enhance learning and cognitive function in animal models – and in humans,” Kempermann adds.

SWNS writer Mark Waghorn contributed to this report.