Scientists are waking up to the health benefits of coffee.
Researchers in the Netherlands found that coffee filters eliminate a chemical that causes heart problems. Meanwhile, an international team of researchers found that the grounds help remove copper and lead from tap water.
The Dutch study asked 30 volunteers to drink 6 cups of unfiltered coffee a day for two weeks. The coffee drinkers showed a 10 percent increase in the amount of hom*ocysteine -- a chemical proven to increase chances of cardiovascular disease -- in their plasma.
The researchers said the results equal a 10 percent increase in risk for heart attack and stroke.
A control group of 34 people drank water, milk, broth, tea, and chocolate drinks instead, and saw no change in their hom*ocysteine levels.
The researchers said it's unclear whether filtered coffee would have the same effect, but they suspect that filters remove diterpenes, substances that raise hom*ocysteine levels.
A group of international scientists found that coffee filters can remove from 78 to 90 percent of dissolved heavy metals such as lead and copper from tap water.
The researchers suggest that the results may be evidence that daily human exposure to heavy metals in cities around the world may be greatly overestimated, and that current public health risk assessment models are inaccurate where coffee makes up a large proportion of water consumption.
"The reason is that coffee grounds have uncharged or negatively charged molecules in them, whereas dissolved heavy metals are positively charged. As a result, the heavy metal ions bind strongly to the coffee," said Mike McLaughlin who works with the Land and Water division of the Australian government research arm, Commonwealth Scientific Industrial Research Organization (CSIRO).
Both copper and lead have long-term toxic effects on humans, and lead is strongly linked to intellectual impairment, especially in infants and young children.
But coffee grounds have a remarkable ability to mop up the heavy metal atoms, according the research by the Australian, Chilean, and U.S. scientists.
The deeper the bed of coffee in the drip-maker, the more effective the removal of heavy metals. The main factor influencing the extent of metal removal is contact time, the scientists found.
It's likely the process also removes other heavy metals such as mercury, cadmium, and zinc from drinking water, although this remains to be tested, McLaughlin said.
"It is also possible tea-bags and tea leaves may work in the same way, but not as well as coffee," he said.
The Environment News Service contributed to this report.
