London, Apr 23 (IANS): We may all be drinking more coffee to help us survive the coronavirus (COVID-19) lockdown, and now researchers have revealed that filtered brew is the safest and healthiest one.

The study, published in the European Journal of Preventive Cardiology, examined links between coffee brewing methods and risks of heart attacks and death and found that coffee drinking was not a dangerous habit. In fact, drinking filtered coffee was safer than no coffee at all. The lowest mortality was among consumers of 1 to 4 cups of filtered coffee per day."Unfiltered coffee contains substances which increase blood cholesterol. Using a filter removes these and makes heart attacks and premature death less likely," said study author Professor Dag S Thelle from the University of Gothenburg in Sweden.

According to the researchers, experiments identified the culprit substances in coffee and found that they could be removed using a filter. A cup of unfiltered coffee contains about 30 times the concentration of the lipid-raising substances compared to filtered coffee.

Between 1985 and 2003, the study enrolled a representative sample of the Norwegian population: 508,747 healthy men and women aged 20 to 79. Participants completed a questionnaire on the amount and type of coffee consumed.

Data was also collected on variables that could influence both coffee consumption and heart diseases, so that these could be accounted for in the analysis. For example, smoking, education, physical activity, height, weight, blood pressure, and cholesterol.

Participants were followed for an average of 20 years. A total of 46,341 participants died. Of those, 12,621 deaths were due to cardiovascular disease. Of the cardiovascular deaths, 6,202 were caused by a heart attack.Compared to no coffee, the filtered brew was linked with a 15 per cent reduced risk of death from any cause during follow up.

For death from cardiovascular disease, the filtered brew was associated with a 12 per cent decreased risk of death in men and a 20 per cent lowered risk of death in women compared to no coffee. "The finding that those drinking the filtered beverage did a little better than those not drinking coffee at all could not be explained by any other variable such as age, gender, or lifestyle habits. So we think this observation is true," Thelle said.

The filtered brew was also less risky than the unfiltered beverage for death from any cause, death due to cardiovascular disease and deaths from heart attacks. "Our analysis shows that this was partly because of the cholesterol-increasing effect of unfiltered coffee," Thelle explained.

The researchers noted that unfiltered coffee did not raise the risk of death compared to abstaining from coffee - except in men aged 60 and above, where unfiltered brew was linked with elevated cardiovascular mortality.