By Craig Weatherby
Coffee has long been the target of calumny, despite a dearth of supporting evidence.
The brew burst on the world scene in the 1500's, quickly capturing fans from Europe to Japan.
Periodically since then, zealots have decried its stimulating effects as dangerous to body or spirit.
While those stances seem more than a bit silly in light of the now-ample science on coffee and caffeine, some concerns remain.
In fact, there's no good evidence that moderate consumption of coffee (or caffeine) is unhealthful.
Benefits clearly outweigh concerns
Countering some minor concerns (see our sidebar, “Coffee concerns: minor at most”), growing evidence indicates that coffee is probably a preventive-health powerhouse.
There's little doubt that coffee's promise stems from its abundance of highly healthful polyphenol-type compounds.
Although polyphenols are often called antioxidants, they don't exert direct antioxidant effects in the body. Instead, they influence gene expression to produce antioxidant, anti-inflammatory, and other beneficial effects.
Fitting with the known properties of its polyphenols, research to date suggests that moderate consumption of caffeinated or decaf coffee appears to help protect against type 2 diabetes, heart failure, stroke, and possibly even breast cancer (see “Does Coffee Curb Breast Cancer?
And coffee is extraordinarily rich in a class of polyphenols called chlorogenic acids, which help stabilize blood sugar and exert metabolic effects that may contribute to weight control.
(Green coffee beans contain more of these compounds, compared with roasted ones, which explains why green coffee extract has recently become a popular dietary supplement.)
minor at most
Natural health advocates often tout the benefits of tea, and claim that drinking regular coffee “exhausts” the adrenal glands … evading the fact that tea also contains caffeine.
While some clinical studies find that coffee stimulates secretion of the stress hormone cortisol, others find no such effect.
Consumption of boiled coffee has been linked to slightly unhealthful changes to blood lipid profiles (Bøhn SK et al. 2012), and a few population studies link habitual drinking of boiled coffee to slightly higher risk of heart attack (Hammar N et al. 2003).
Finally, coffee with caffeine can also raise blood pressure in people unused to drinking it, but this effect disappears after drinking it for a few days.
Although large amounts of caffeine can be risky for people with heart-rhythm problems, moderate caffeine consumption (200-400mg daily) appears safe and is proven to boost mental focus and clarity.
The caffeine content of coffee ranges from about 65 mg for a single cup (30 ml) of espresso to about 145 mg for an 8 oz. cup (237 ml) of drip coffee.
Most studies indicate that moderate coffee consumption cuts the risk of coronary heart disease slightly … and that coffee exerts positive effects on the critically important endothelium of drinkers' arteries.
The endothelium is the layer of cells that line blood vessels, which performs functions critical to cardiovascular health and the risk of cardiovascular disease.
The heart-health benefits of coffee just received more support … this time from a study suggesting that it may help explain the extreme longevity of Greek island dwellers.
Study targeted long-lived Greek islanders
The inhabitants of Ikaria – a Greek island in the Aegean Sea – live longer than almost any other people in the world.
Ikaria is named for Icarus of Greek mythology, who fell into the sea after flying too close to the sun on wings held together with wax.
Today, Ikaria is considered one of the world's five “Blue Zones” – places where people live to an advanced age: Okinawa (Japan), Sardinia (an island off Italy); Nicoya (Costa Rica), Icaria, and the Seventh Day Adventists living in Loma Linda, California.
One in three Ikarians live into their 90s … likely because of their healthy Mediterranean diets and low-stress, active lifestyles.
But another factor – coffee, especially the boiled coffee characteristic of Greece and the Middle East – may help explain Ikarians' longevity.
Greek-Arab style coffee aids arteries
The study was conducted by scientists from the University of Athens Medical School, led by Professor Gerasimos Siasos.
The Athens team set out to probe possible links between Ikarians' coffee-drinking habits and the performance of their arteries' endothelial lining (Siasos G et al. 2013).
Their endothelial health was ranked using a standard measure called flow-mediated dilatation of the brachial artery or FMD.
Compared with the Ikarians who consumed coffee brewed in other ways, those who drank boiled, Greek-style coffee enjoyed superior endothelial function.
Boiled, Greek-style coffee is higher in polyphenol-type antioxidants and lower in caffeine, compared to coffee made by other methods.
(Likewise, espresso has more antioxidants and less caffeine than regular coffee.)
Out of a sample of 673 permanent Ikaria residents aged 66-91, Siasos and his colleagues randomly selected 71 men and 71 women for the study.
The scientists gathered relevant health data (e.g., high blood pressure, blood sugar control) on the volunteers, tested their endothelial health and asked detailed questions about the participants' health, lifestyles, and diets, including coffee drinking.
In addition to diets rich in fish, fruits, vegetables, and extra virgin olive oil, most of the participants reported taking a daily nap and enjoying gardening and frequent walks on the mountainous island's steep hillsides.
The participants were placed into three categories of coffee consumption:
Low (40 percent of subjects) – less than 6.7 oz. (200 ml) per day
Moderate (48 percent of subjects) – 6.7-15.2 oz. (200-450 ml) per day
High (13 percent of subjects) – more than 15.2 oz. (450 ml) per day
More than 87 percent of the volunteers consumed boiled Greek-style coffee every day.
The volunteers' FMD scores related to their coffee consumption in a “dose-dependent” fashion, which virtually proves that the coffee was responsible.
And those who mainly drank boiled Greek-style coffee had significantly higher FMD scores, compared with those consuming coffee prepared in other ways.
As the researchers wrote, “Chronic coffee consumption is associated with improved endothelial function in elderly subjects, providing a new connection between nutrition and vascular health.” (Siasos G et al. 2013)
While all of the volunteers consumed coffee daily and had above-average FMD scores compared with the typical Westerner, those who consumed mainly boiled Greek-style coffee had the healthiest endothelial function.
Even among the participants with high blood pressure, those who drank boiled Greek-style coffee showed superior endothelial function.
As Dr. Siasos told The New York Times, “This boiled coffee seems to generate [more] antioxidant substances.”
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Siasos G, Oikonomou E, Chrysohoou C, Tousoulis D, Panagiotakos D, Zaromitidou M, Zisimos K, Kokkou E, Marinos G, Papavassiliou AG, Pitsavos C, Stefanadis C. Consumption of a boiled Greek type of coffee is associated with improved endothelial function: The Ikaria Study. Vasc Med. 2013 Mar 18. [Epub ahead of print]