If you’re a regular coffee drinker, you could be ensuring the integrity of your DNA, according to the results of a new German study. The research found that those who drank three cups of a dark roast coffee blend per day experienced 27 percent fewer DNA strand breaks in their white blood cells than those who drank water instead.

Previous research has shown that coffee consumption can decrease the instances of oxidative damage in our white blood cells. This damage is caused by an imbalance between the production of reactive oxygen species called ‘free radicals’ - atoms, molecules, or ions that end up with one or more unpaired electrons, which makes them highly reactive with other cellular structures - and the cell’s ability to counteract their harmful effects.

If left unregulated, free radicals can damage all of the components of a cell, including its proteins, lipids, and DNA. When our DNA is damaged, the body isn’t always able to repair it, or isn’t capable of repairing it properly, which can lead to compromised function, or mutations. If serious enough, the mutations can develop into cancer, and the lack of function will result in accelerated cellular ageing.

The researchers wanted to take the investigation into the link between DNA damage and coffee consumption further by looking into the effects of the popular beverage on a person's levels of spontaneous DNA strand breaks. Stand breakage occurs when one or both strands of a DNA double helix are pulled apart, and can sometimes be mashed together again with different types of broken DNA, causing genome rearrangements. In some cases, this will promote the growth of cancer cells. Spontaneous stand breakage is widely used by scientists as a marker of poor health, or as an indiction of a potential health risk.

The team, led by T. Bakuradze from the University of Kaiserslautern, enlisted 84 men aged between 19 and 50, who had healthy weights and diets, were non-smokers, and did not use drugs or alcohol on a regular basis. The volunteers were asked to consume either three cups (750 ml) of fresh coffee brew or plain water, every day for four weeks - one in the morning, one at noontime, and one in the afternoon. The coffee was a special roasted and blended Arabica coffee, and was served black, and the volunteers were given the option of having one teaspoon of sugar. Other caffeinated products were avoided during this time.

Before and after the coffee/water consumption phase, spontaneous DNA strand breaks were measured.

Publishing in the European Journal of Nutrition, the researchers describe what they found:

"At baseline, both groups exhibited a similar level of spontaneous DNA strand breaks. In the intervention phase, spontaneous DNA strand breaks slightly increased in the control (water only) group, whereas they significantly decreased in the coffee group, leading to a 27 percent difference ... Food frequency questionnaires indicated no differences in the overall diet between groups, and mean body weight during the intervention phases remained stable. The consumption of the study coffee substantially lowered the level of spontaneous DNA strand breaks in white blood cells."

The results correlate to findings of previous research - one from 2007 that included 38 participants and showed marked protection against oxidative DNA damage after just five days of consuming freshly prepared filtered coffee brew, and another from 2010, showing a very slight reduction of oxidative DNA strand breaks in the volunteers' lymphocytes after drinking instant coffee. "Taken together, the observed DNA protective effects associated with coffee consumption may be considered beneficial to human health," Bakuradze's team says of the body of research related to coffee consumption and DNA integrity.

The sample sizes are usually pretty small in these kinds of trials - plus the German study only included male participants - which means we can't rush to take the results of any one of them as gospel. But together they paint an intriguing picture of coffee as being something we're better off drinking than not. Which is just as well, because early last year, the International Coffee Organisation reported that between 2012 and 2013, world coffee production reached 145.1 million bags, which is the largest amount on record. So... good job, team?

Except, of course, the fact that all that consumption is wreaking havoc on the environment, and more so than ever before, as researchers reported last year. In the immortal words of George Costanza: