Cocoa, coffee and caffeine: how helpful (or harmful) is a cup of joe?

The world gulps hundreds of millions of cups of coffee every day — so what is all this java doing to our brains and bodies?

For many, coffee is a morning eye-opener, thanks to the stimulating effects of caffeine, but other compounds native to the coffee bean include antioxidants that have been linked to a lower risk of skin cancer, Alzheimer’s, heart disease and diabetes. Just a few weeks ago, a Harvard School of Public Health study found that java may even prevent suicide; individuals who drank two to four cups of coffee every day were less likely to commit suicide than those who didn’t drink it.

But unfortunately, studies touting the benefits of coffee are often followed by others that highlight its adverse effects on health. The latest, published in the journal Mayo Clinic Proceedings, studied health records of 45,000 people who reported their coffee-drinking habits and concluded that younger people under age 55 who drank more than 28 cups a week were 21% more likely to die prematurely during the 17 year study than those who drank less. (Older coffee drinkers didn’t show such an increased risk of early mortality.)

While the heavy coffee drinkers were also more likely to be less fit and to smoke cigarettes — both factors that can contribute to early death — the relationship between more coffee and earlier death continued to hold even after the scientists adjusted for these effects.

So is that morning cup of coffee a health-booster or a health hazard?

That answer depends on how the studies that examine this question are designed, and the type of coffee in question — as well as who is doing the drinking.

Unlike the latest analysis above, some studies in the past did not adjust for factors other than coffee that could affect outcomes like mortality, cancer rates or cognitive measures. A 1981 study, for example, connected coffee to an increased risk of pancreatic cancer, but other analyses showed conflicting associations. Later research concluded that these contrary findings were due to the fact that some of the studies failed to control for potentially confounding factors such as smoking, while others were subject to the errors of having drinkers recall how much they consumed.

It’s also important to understand what the studies are designed to measure. When it comes to brain function, for example, it turns out that caffeine in coffee acts as a stimulant that can sharpen cognitive function but doesn’t necessarily improve memory or learning; the distinction, however, isn’t often made in media reports on coffee studies involving cognition or even the risk of Alzheimer’s disease.

The effects of coffee on the body can also change over time, and studies don’t always tease apart the different health outcomes of participants by age. A long-term java habit’s effect on the hearts and brains of older drinkers, for instance, may differ from that of a short-term one as cells and tissues become tolerated to the chemicals in the coffee.

For example, frequent and long-term coffee drinking — about four or more cups a day — has consistently been linked to a nearly 50% lower risk of type 2 diabetes compared to non-drinkers, while the effect of fewer cups is less consistent. Such a coffee habit isn’t all beneficial, however; high consumption among pregnant women has been linked to a lower birth rate.

How the coffee is prepared can also make a difference; some studies found that unfiltered coffee — like French Press — increased cholesterol levels while paper-filtered coffee did not, but most studies of coffee drinkers don’t distinguish between different preparations….. Read the full article