The researchers found that among more than 21,000 Norwegian adults, those who indulged in several cups of coffee a day generally had slightly higher cholesterol than non-drinkers. The extent of the difference, however, depended on brewing method.
People who drank the "least filtered" kinds of coffee — made with a French press, for example — showed the largest cholesterol effects: On average, those who drank six or more cups a day had total cholesterol levels that were eight to 12 points higher, versus non-drinkers.
Espresso lovers were next, followed by women who drank filtered drip coffee (with no cholesterol effects seen among their male counterparts).
The findings are in line with past studies suggesting that unfiltered coffee might have a particular effect on cholesterol levels, according to researcher Dr. Maja-Lisa Løchen.
Unfiltered brews include coffees that are boiled or made using a French press or "plunger." Espresso also falls into that category, but it is relatively more filtered than the other varieties, said Løchen, a professor at UiT The Arctic University of Norway.
Brewing methods matter because coffee contains natural oils that can raise blood cholesterol. Researchers have long known that unfiltered coffees, by exposing the grounds to hot water for a prolonged time, contain more of those oils.
In fact, Løchen said, it was the Tromsø Study from Norway that first showed, in the 1980s, that "it's all in the brewing."
In those days, she noted, boiled coffee was the unfiltered variety of choice. But now espresso and plunger coffees are all the rage, so Løchen and her colleagues used more recent data from the Tromsø Study to look at the relationship between those brews and blood cholesterol.
"Norwegians love coffee," Løchen said, "and Norway has the second highest coffee consumption in the world."
The findings, published online May 10 in the journal Open Heart, are based on more than 21,000 adults aged 40 and up who reported on their coffee drinking habits, exercise levels and alcohol intake.
On average, study participants drank four to five cups of coffee a day. Those who indulged in boiled or French press coffee — six or more cups a day — showed the biggest cholesterol elevations, relative to non-drinkers, the findings showed.
Next came people who said they downed three to five cups of espresso a day. Their total cholesterol was roughly 4 to 6 mg/dL higher, versus people who did not drink espresso. Finally, women who drank at least six cups of filtered coffee each day had cholesterol levels that were 4 mg/dL higher, on average, versus women who never drank filtered coffee.
However, a registered dietitian who was not involved in the study had some caveats.
For one thing, there was no information on participants' overall diet, said Connie Diekman, a food and nutrition consultant and former president of the Academy of Nutrition and Dietetics.
Nor is it clear whether people regularly doused their coffee of choice with sugar and cream, Diekman pointed out.
So, she said, the question remains, was it the coffee, the cream or the foods people consumed with all those cups of coffee?
"Coffee, in and of itself, is likely a very small player in elevating cholesterol," Diekman said. "So rather than worry about how coffee might be impacting cholesterol, look at your whole diet and establish other healthful life behaviors."
Løchen also pointed to the bigger picture, noting that moderate coffee intake (up to five cups a day) has been linked to a lower risk of heart disease and a longer life.
Angel Planells is a Seattle-based registered dietitian and spokesperson for the Academy of Nutrition and Dietetics. He said that filtered or instant coffees might be the best choices for people watching their cholesterol. But again, overall diet and lifestyle are key.
If you really enjoy that latte or mocha, Planells said, there may be other ways to trim some "bad" fat from your diet — like cutting down on processed meat or fried foods.
That said, some people should be especially mindful about the caffeine in coffee, Planells said — including pregnant women and anyone with potential caffeine side effects, like trouble sleeping or the "jitters."