Depending on who you listen to, coffee is either a superfood (well, superdrink) or a health hazard, yet a remarkable new study demonstrates that store-bought Java beans can be used to disrupt the formation of protein plaques that contribute to the development of Alzheimer’s disease. And while the experiments were conducted in a petri dish, the researchers say it may be possible to attain similar results in vivo by drinking a few cups of Joe a day.
Alzheimer’s disease is one of a group of disorders called tauopathies, which are characterized by the aggregation of tau proteins in the brain. Given that recent studies have suggested a possible neuroprotective effect of coffee, the study authors decided to see how a regular espresso influences the development and behavior of these pathological protein clumps.
Using commercial coffee beans, the researchers poured themselves an espresso, before isolating a few of the compounds in their beverage. Specifically, they selected the alkaloids caffeine and trigonelline, as well as the flavonoids genistein and theobromine, for incubation alongside a shortened form of the tau protein for up to 40 hours.
A whole coffee extract was also used so that the researchers could observe the combined effect of all these compounds on the aggregation of tau proteins.
Results showed that caffeine, genistein, and the coffee extract all inhibited the formation of tau plaques in a dose-dependent manner, whereby the length of the tau filaments decreased as concentrations of these various compounds increased. The full coffee extract was the most effective, and was found to disrupt the shape of the tau aggregates.
“The effect of coffee extract was remarkable: even in the presence of low quantities of the mixture, the formation of long fibrils was compromised and only few short fibrils were visible,” explain the researchers.
Further experiments revealed that caffeine also has the potential to bind pre-formed tau fibrils, while the coffee extract prevented the formation of tau condensates, which are thought to be a precursor to plaques. “Therefore, our results show a further interesting property of the coffee extract in interfering with the early events, leading to the pathological accumulation of tau,” write the study authors.
Having seen how these various components impede the formation of tau fibrils, the researchers then decided to investigate the impact of this stunting on the protein’s toxicity. They therefore added human embryonic kidney cells to the mix, and found that tau proteins were less capable of harming these cells when coffee compounds were present.
According to the study authors, drinking two or three espressos per day can provide significant quantities of both caffeine and genistein, both of which can cross the blood-brain barrier and exert their neuroprotective effects. Given that the concentration of tau proteins in the brain is typically around 25 times lower than the levels used in this study, the researchers speculate that drinking coffee may help to prevent the aggregation of these proteins and protect against Alzheimer’s disease.
Naturally, such claims will need to be verified by proper clinical trials, and much more research is needed to confirm the neuroprotective power of coffee. Nevertheless, the study authors say that “based on the bioavailability of coffee components in the brain, and on the results of our study, we expect that moderate coffee consumption may provide a sufficient amount of bioactive molecules to act separately or synergistically as modulators of tau protein aggregation and toxicity.”
The study is published in the Journal of Agricultural and Food Chemistry.
