By Tom Nordlie
GAINESVILLE, Fla. - If that take-out coffee seems more invigorating than usual today, it might not be your imagination - it may be the java's packing a bigger dose of caffeine than you expected, even if it's decaf.
Scientists at the University of Florida College of Medicine recently analyzed 16-ounce servings of caffeinated coffee from specialty shops and found almost twice as much caffeine in the strongest brew - Starbucks regular, at 259 milligrams - compared with the weakest, Dunkin' Donuts regular, at 143 milligrams.
Another type of Starbucks caffeinated coffee purchased from a single Gainesville store for several consecutive days varied even more, from 259 milligrams to a whopping 564 milligrams, almost as much caffeine as three maximum-strength NoDoz, said Bruce Goldberger, Ph.D., an associate professor and director of toxicology with UF's department of pathology, immunology and laboratory medicine and an associate professor with the UF department of psychiatry's division of addiction medicine.
And while some people may think they're bypassing the stimulant, seven decaffeinated coffees from various shops all contained some caffeine, though less than 18 milligrams per 16-ounce serving.
The results are being presented today at the annual meeting of the Society of Forensic Toxicologists in Portland, Ore., and appear in the current issue of the Journal of Analytical Toxicology.
"I don't think people really know that there is a wide range in (coffee's) caffeine content," said Goldberger, who led the study and is the editor of the journal. "Our experience with specialty coffee is that it is not consistent." But coffee drinkers may have to live with uncertainty, an important consideration for those who monitor their caffeine consumption, he said.
Caffeine can enhance human performance by increasing alertness and speeding reaction time, but it can cause increased heart rate, blood pressure and anxiety, according to previous research cited in the UF study.
The caffeine content of Starbucks coffee varies, according to a written statement provided by spokeswoman Lara Wyss in Seattle in response to a request for comment on the UF study.
Quoting from the statement: "We emphasize that any absolute numbers reported on caffeine levels in Starbucks coffee do not reflect what a customer would receive in every cup of Starbucks coffee. There are many variables that contribute to caffeine content from cup to cup," including the type of bean, roasting and brewing methods, and grind.
Starbucks regular drip coffees contain an average of 200 milligrams of caffeine per 8-ounce serving; their decaffeinated drip coffees contain an average of 5 milligrams to 11 milligrams of caffeine per 8-ounce serving, according to the statement. A "frequently asked questions" feature on the Starbucks Web site indicated that the company intends to add caffeine-content information to the site in a future upgrade.
Caffeine is a stimulant that naturally occurs in more than 60 plants, including coffee, according to the International Food Information Council Foundation in Washington, D.C. The average American consumes about 200 milligrams of caffeine per day, mainly from coffee. An 8-ounce cup of drip-brewed coffee typically contains 85 milligrams of caffeine.
Moderate caffeine intake, defined as 250 milligrams per day, is not associated with any health risk, according to Medline Plus, a health information Web site maintained by the U.S. National Library of Medicine and the National Institutes of Health.
Though caffeine is recognized as an addictive substance, UF experts don't usually encounter patients seeking help for caffeine dependence, said Mark S. Gold, M.D., a distinguished professor at UF's McKnight Brain Institute and chief of addiction medicine in the psychiatry department.
"Caffeine dependence is a non-issue for me because people won't leave their home for it, won't mortgage their house for it, won't choose caffeine over their wife," said Gold, who recently co-authored a study on coffee's caffeine content.
The UF study was conducted in two phases by Goldberger, toxicologist Edward Cone, Ph.D., of ConeChem Research in Severna Park, Md., and Rachel McCusker, B.S., a UF biological scientist. Funding was provided by Goldberger's laboratory.
The first phase included a one-time purchase of 14 caffeinated brewed coffees from six retailers in Bethesda and Severna Park, Md., including Starbucks, Dunkin' Donuts, Big Bean, Hampden Café, Royal Farms and Einstein Bros. Six espressos and seven decaffeinated brewed coffees also were purchased. Caffeine was isolated from samples of coffees using chemical and mechanical treatments, then measured by gas chromatography.
The espressos ranged in size from 40 milliliters to 170 milliliters and contained 58 milligrams to 185 milligrams of caffeine, with the larger servings containing more caffeine. The decaffeinated coffees all contained less than 18 milligrams of caffeine per 16-ounce serving. The U.S. Food and Drug Administration currently does not require decaffeinated coffee to be absolutely caffeine-free, an agency spokesperson said.
The study's second phase used 16-ounce cups of Starbucks' Breakfast Blend, a mix of Latin American coffees, purchased on six consecutive days from a single Gainesville store and analyzed by the same method. Results for the six days were, in order: 564 milligrams, 498 milligrams, 259 milligrams, 303 milligrams, 300 milligrams and 307 milligrams.
The study results demonstrate the need for retailers to inform consumers of the caffeine content in ready-to-drink coffee because many of the beverages contain so much, said Michael F. Jacobson, Ph.D., executive director of the Center for Science in the Public Interest in Washington, D.C. "Until now the focus has been on coffee packages, but this study indicates the need to have caffeine-content information at coffee shops as well," Jacobson said.
|
|
|
|
|
Roving cells might eventually help
doctors predict heart and kidney problems.
|
By Tom Nordlie
GAINESVILLE, Fla. - Scientists don't know why cells that normally line blood vessel walls are sometimes found circulating in the blood itself, but a University of Florida study that found abnormally large numbers in kidney disease patients suggests the roving cells might eventually help doctors predict heart and kidney problems.
Blood samples from kidney dialysis patients contained about 50 percent more circulating vessel wall, or endothelial, cells than did samples from healthy people, said nephrologist Mark Segal, M.D., Ph.D., a UF assistant professor of medicine who led the study. And compared with healthy people, patients who were not on dialysis but suffered from diabetes or high blood pressure had over 100 percent more circulating cells.
The findings were published this month in the American Journal of Kidney Diseases. "Right now, there aren't good ways to know what someone's arteries look like, but we know there are lots of different ways that arteries can be injured," said Segal, with the UF College of Medicine's division of nephrology, hypertension and renal transplantation. "So it would be nice to have a simple readout to tell us how well the arteries as a whole are doing, and that's what we hope the circulating endothelial cells will lead us to."
Endothelial cells form the thin, innermost layer of blood vessel walls, known as the endothelium, which helps regulate blood pressure and the movement of cells and molecules. The average human body contains enough endothelial cells to cover an area about the size of a football field, he said.
Discovered about 30 years ago, circulating endothelial cells are not well understood, Segal said. He believes the number of circulating cells increases when the endothelium is damaged by factors such as stress, high blood pressure, cholesterol and homocysteine, a common amino acid found in red meat.
High blood pressure also is a leading cause of kidney disease,so many dialysis patients suffer from weakened circulatory systems. Each year, about 8 percent of U.S. adult kidney dialysis patients suffer major cardiovascular events such as heart attack or stroke, 10 times the rate for the general public, he said.
Dialysis uses a machine to filter waste products from the bloodin patients suffering kidney failure. Almost 400,000 Americans need dialysis to stay alive, according to the National Kidney Foundation.
"Circulating endothelial cells could be a sort of barometer for a patient's risk for developing vascular diseases," Segal said. "If you have a patient with high blood pressure it could be very costly to bring down their blood pressure to below 130 over 80. But if we know that person is at high risk of future cardiovascular events or end-organ damage, like kidney failure, then it's worth the money. However, if another patient has high blood pressure but is at low risk of future events, then we may only need to bring down their blood pressure to 140 over 90."
For healthy adults, blood pressure of less than 120 over 80 is considered optimal, according to new guidelines released this year by the National Heart, Lung and Blood Institute.
When damaged, the endothelium produces substances that constrict blood vessels, promote clotting and attract immune system cells, all ofwhich may cause buildup of artery-clogging plaque, a condition known as atherosclerosis or hardening of the arteries. If plaque becomes unstable a clot could form, blocking blood flow to the heart causing a heart attack, or a clot could break off, going to the brain causing a stroke.
In the UF study, Segal and researchers Mehmet Koc, M.D., and Azra Bihorac, M.D., also compared groups of kidney dialysis patients and found those who suffered from atherosclerosis but in whom the disease was well-controlled had the fewest circulating cells. Patients who did not suffer from atherosclerosis had twice as many circulating cells, and patients with uncontrolled atherosclerosis had four times as many.
"That surprised us," Segal said. "Whether that (data resulted)because the patients with stable atherosclerosis are treated with medication and it lowers their risk is still up in the air."
In the study, funded by the National Institutes of Health andthe UF nephrology division, researchers examined 22 healthy, nonsmoking adults, 29 kidney dialysis patients, 10 people with chronic kidney disease and diabetes, and seven people with chronic kidney disease and high blood pressure. The dialysis patients also were evaluated for any history of cardiovascular disease.
Blood samples from each test subject were chemically treated, then cells were mounted on slides and treated again, and examined undera microscope to identify and count circulating endothelial cells. Finally, the presence of the cells was confirmed with another chemical treatment.
Segal said larger studies could show definitively whethercirculating endothelial cells provide an accurate gauge of the endothelium's condition and whether researchers could use the cells to evaluate therapies designed to improve endothelial health. He said he plans to investigate the interaction between circulating endothelial cells and two types of immune system cells associated with the
development of atherosclerosis: monocytes and T cells.
A larger, long-term study might help explain the true effects ofcirculating endothelial cells on blood vessel walls and on cardiovascular disease, said nephrologist Prabir Roy-Chaudhury, M.D., Ph.D., an associate professor with the University of Cincinnati's department of internal medicine.
"It's unclear, in my mind at least, whether circulating endothelial cells are just an indicator of endothelial damage or whetherthey have some sort of reparative process as well," Roy-Chaudhury said. "What's important is that Mark has begun to look at circulating endothelial cells in (this) population of patients."
|
|
“When healthy we should continue to be the men we vowed
