An apple a day keeps the doctor away, or so the saying goes.
The old wives' tale may hold some truth when it comes to neurologists, with new research suggesting the popular fruit boosts brain health in mice.
An antioxidant in apple peel was linked to increased nerve cell survival in the vital organ when injected into a mouse's abdomen.
Other compounds in the flesh of an apple were also associated with the formation of new nerve cells in the brain.
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Writing in the journal Stem Cell Reports, scientists from the German Center for Neurodegenerative Diseases in Dresden said: "An apple a day keeps the doctor away. There may be some truth to this aphorism.
"Apart from being a source of energy, food is known to influence an individual's overall fitness."
The German scientists injected the antioxidant quercetin, which is highly abundant in apple peel, into the abdomen of adult mice.
The team then focused on the rodents' hippocampus, an area of the brain involved in learning and memory.
Results suggest the quercetin injection promoted the survival and differentiation of nerve cells, known as neurones, in the animals' hippocampus.
Differentiation occurs when a cell changes its function as it divides, usually to become more specialised.
The scientists then administered the compound 3,5-dihydroxybenzoic acid, found in apple flesh.
This too significantly increased "neural precursor cell proliferation and neurogenesis". Neural precursors have the ability to differentiate into neurones, via a rapid division process known as proliferation.
Neurogenesis describes how new neurones are formed in the brain.
Feeding the mice apple juice had no effect, however. This may have been due to the antioxidant levels being too low in the popular drink.
Further research is required to uncover if these antioxidants have a similarly promising effect in other animals, including humans, according to the scientists.
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