22 Nov Better to drink dark roast coffee
According to data from the Harvard T.H. Chan School of Public Health in Boston, MA, about 54
percent of all adults in the United States drink coffee on a daily basis. A 2016 study from the
University of Ulster in Coleraine, United Kingdom, concluded that the health benefits of
moderate coffee consumption "clearly outweigh" the potential risks.
One of these benefits is that coffee seems to protect the brain against cognitive impairments and
boost thinking skills.
How does this happen, and what is it about coffee that is so beneficial to cognitive health? These
are some questions that a new study from the Krembil Brain Institute — part of the Krembil
Research Institute in Toronto, Canada — aims to answer.
"Coffee consumption does seem to have some correlation to a decreased risk of developing
Alzheimer's disease and Parkinson's disease," notes Dr. Donald Weaver, who is co-director of
the Krembil Brain Institute.
"But we wanted to investigate why that is — which compounds are involved and how they may
impact age-related cognitive decline," he adds.
Dr. Weaver and team's findings — published in the journal Frontiers in Neuroscience — suggest
that the key to coffee's brain-protecting benefits lie not in its caffeine content, but in the
existence of compounds released in the process of roasting the coffee beans.
In the current study, the researchers decided to look into the effects of three types of coffee:
caffeinated dark roast, caffeinated light roast, and decaffeinated dark roast.
"The caffeinated and decaffeinated dark roast both had identical potencies in our initial
experimental tests. So we observed early on that its protective effect could not be due to
caffeine," says study co-author Dr. Ross Mancini, a research fellow in medicinal chemistry.
Gradually, all the links fell into place, as the researchers started focusing on a set of compounds
called phenylindanes, which form during the process of roasting coffee beans and lend coffee its
It is the phenylindanes, rather than any other coffee-related compounds, that seem to inhibit the
amalgamation of tau and beta-amyloid. These are toxic proteins, of which the excessive buildup
in the brain is a key factor in neurodegenerative conditions such as Alzheimer's and Parkinson's
"So phenylindanes are a dual inhibitor. Very interesting, we were not expecting that," Dr.
It appears that a longer roasting time causes the coffee beans to produce more phenylindanes.
This suggests that dark roasted coffee — whether regular or decaf — has the strongest protective
effect on the brain.
"It's the first time anybody's investigated how phenylindanes interact with the proteins that are
responsible for Alzheimer's and Parkinson's," says Dr. Mancini.
In the future, the researchers aim to conduct more detailed investigations on the properties of
phenylindanes, and their effects on the body once ingested.
"The next step would be to investigate how beneficial these compounds are, and whether they
have the ability to enter the bloodstream, or cross the blood-brain barrier," Dr. Mancini adds.
For the researchers, another exciting aspect of this discovery is that these coffee compounds are
natural and do not require synthesis in the laboratory, which makes them less complicated to
"Mother Nature is a much better chemist than we are and Mother Nature is able to make these
compounds. If you have a complicated compound, it's nicer to grow it in a crop, harvest the crop,
grind the crop out and extract it than try to make it."
At the same time, however, Dr. Mancini stresses that before they can add phenylindanes as a
treatment option for neurodegenerative conditions, they need to conduct a lot more research on
how these compounds would work in a therapeutic context.
"What this study does is take the epidemiological evidence and try to refine it and to demonstrate
that there are indeed components within coffee that are beneficial to warding off cognitive
decline," says Dr. Mancini.