In addition to brightening our mornings and keeping us all day long, coffee has shown numerous health benefits: on the one hand, its caffeine content improves alertness and short-term memory – but studies suggest that coffee can have effects long-term protectors in the brain, too.
Drinking coffee was previously associated with a reduced risk of Alzheimer's and Parkinson's disease, and now scientists say they may have an idea of why. It turns out that the phenylindanes – chemical compounds that form during the fermentation process – inhibit the growth of proteins associated with degenerative brain diseases. And the darker the roast, they say, the more of these protective compounds exist in each cup.
For the new study, published in Frontiers in NeuroscienceResearchers at the Krembil Brain Institute in Toronto analyzed the chemical components of three different samples of Starbucks Via instant coffee: dark baked, dark, dark decaffeinated baked yeast. They then exposed extracts from each sample to two types of proteins – beta and amyloid – which are known as Alzheimer's and Parkinson's. Studies have shown that, as these conditions progress, these proteins tend to form clumps (known as amyloid plaques and tau protein tangles) in the brain.
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All three coffee extracts prevented the clumping of these proteins, suggesting that something in America's favorite morning beverage might be protective against the progression of the disease. And because the researchers did not notice any difference in the effectiveness of regular versus decaffeinated beers, they determined that it is likely not the caffeine that is providing these benefits.
They noted, however, more inhibitory effects of the two dark roasts compared to the roast clear. This led the researchers to think of phenylindanes – compounds formed from the decomposition of acids during coffee roasting, which are mainly responsible for the bitter taste of coffee.
Phenylindans are found in higher concentrations in coffees with higher roasting time, such as dark and expressed roasts. They have been shown to exhibit "surprisingly potent antioxidant activity," the authors wrote in their paper, but their ability to interact with amyloid and tau proteins has not been previously reported.
In additional laboratory studies, they found that a mixture of phenylindane actually prevents the accumulation of disease-related protein; in fact, it was the only compound studied that had an effect on amyloid and tau proteins. For tau proteins, it exhibited more potent inhibition levels than any other compound investigated.
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Given that both extracts of dark roasted coffee showed more potent levels of protein inhibition compared to the clear roasted, the authors proposed that it is the phenylindane component of coffee that is "largely responsible" for this effect. (And good news for decaffeinated consumers: because the decaffeination process happens before the roasting process, the authors assume that it has no effect on the levels of phenylindan.)
This does not necessarily mean that everyone should start drinking espresso coffee or toasting their coffee beans darker nonetheless. The research is still preliminary, according to lead author Donald Weaver, MD, co-director of the Krembil Brain Institute, and much is still unknown about how these compounds actually work in the human body. (In addition, other research has suggested that lighter roasts have higher levels of different beneficial compounds, so it can still be a game for health in general.)
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Weaver said in a press release that he hopes this research will lead to further study of fenilindans, and possibly even the development of drugs that can be used to treat neurodegenerative diseases. He also said that it is good to know that coffee has these naturally good properties for you, even if there is not enough evidence to drink just for these reasons.
"What this study does is pick up the epidemiological evidence and try to refine it and demonstrate that there are indeed components within the coffee that are beneficial to stave off cognitive decline," Weaver said. "It's interesting, but are we suggesting that coffee is a cure? Absolutely not."
Experts say the best way to keep your brain proof of aging is to follow a healthy diet, exercise regularly and get enough sleep. And if it turns out that a daily cup of joe fits into that plan, we definitely are all for that.
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