Are you one of the millions of Americans who can't start the day without a steaming cup of coffee? Growing dependence on that morning caffeine jolt has made the U.S. one of the biggest coffee consumers in the world, swallowing about one-third of the world's coffee production. Is that good or bad? Hard to tell. Decades of conflicting research about the potential benefits and harm of the popular bean have created so much confusion that most coffee drinkers have long since given up trying to sort it out.
But if you like your brew and you like it strong, you might want to consider a study being released this week in the American Journal of Clinical Nutrition about the effect of unfiltered coffee on the heart. It might persuade you to reach instead for a glass of orange juice.
Researchers from the Netherlands studied the effect of coffee consumption on blood levels of homocysteine, a naturally occurring substance that forms when the body breaks down protein. Elevated levels of homocysteine have long been associated with an increased risk of heart disease. Exactly how this amino acid harms the heart is unclear, but our best guess is that it either makes the blood clot more frequently or damages the lining of blood vessels in the heart. (Genetic defects and vitamin deficiencies have also been shown to cause an elevation in homocysteine.)
The Dutch researchers focused on strong, unfiltered coffee, and their results are not great news for folks who drink large quantities of caffeine. After just a two-week period of drinking six cups of unfiltered coffee a day, homocysteine concentrations increased 10% in subjects who started out with normal levels. At the same time, cholesterol levels shot up 10% and triacylglycerols (other fatty substances) 36%--both precursors to artery-clogging atherosclerotic plaque.
The bottom line, according to the authors: drinking 48 oz. of unfiltered coffee a day may carry a 10% increase in risk for heart attack or stroke. An incidental but equally important finding was that levels of vitamin B-6 decreased 21%.
Why would unfiltered coffee be more dangerous than filtered? A leading suspect is a group of substances called diterpenes, found widely in nature--and in coffee beans. Diterpenes are known to raise homocysteine levels, and the paper filters used in coffee machines are usually fine enough to catch them. Some coffee roasters prepare their beans with processes that remove some of the offending diterpenes. Check with your favorite brewer for details.
The good news for coffee lovers: increased levels of homocysteine aren't necessarily permanent. Removing the offending agent--in this case, unfiltered coffee--will help bring the levels back to normal, as will increasing your intake of the B vitamins B-6 and folic acid. Vitamin supplements, green leafy vegetables and citrus fruits are good sources of folate.
Moderate coffee consumption (three to five cups a day) is probably safe for most people. But individuals at high risk of cardiovascular diseases should exercise caution and cut back on those double-tall lattes. Orange juice, rich in folate, is certainly a healthier wake-up drink. It may not have that caffeine zing, but it's full of minerals and vitamins and will give you a lot more nutritional bang for your buck.