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Caffeine Side Effects
Caffeine is probably the most widely used drug in the world, being a substance that alters bodily function when ingested. The FDA recognizes it as a safe food substance that is contained in coffee, tea, soft drinks, energy drinks and chocolate made from cocoa beans. Its main action is that of a central nervous system stimulant that can enhance mental as well as physical function.
Coffee drinking makes up most of caffeine consumption worldwide. It has been linked to many good and bad effects and has been a subject of research and debate with regards to health. On the good side, coffee has been cited for its antioxidant properties, athletic performance and memory enhancement and respiratory benefits. These benefits are usually associated with moderate intake of coffee (about three to four cups per day). However, caffeine has also been blamed for cardiovascular side effects like increases in heart rate and blood pressure especially when taken in large amounts.
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Diabetes and Caffeine
Recent reports have been conflicting about the effects of caffeine consumption on people with diabetes mellitus. A study done at the Duke University Medical Center published in 2004 cites that caffeine decreases glucose metabolism and increases insulin resistance among type 2 diabetic patients who were habitual coffee drinkers. This means that blood sugar levels are significantly increased and its absorption is impaired when coffee is taken with a carbohydrate-containing food. Another study done in Canada and published in 2008 showed similar results, in that coffee had a negative effect on glucose metabolism compared to decaffeinated coffee given to the subjects. However, the authors hypothesized that since roasted coffee contains only 1 to 2 percent caffeine and has more than 600 other active volatile components, it is also possible that the negative side effects of coffee may be due to any of these components, including but not necessarily caffeine.
On the other hand, a study done in the Netherlands and published in 2006 showed that high coffee consumption was associated with a significantly lower risk of type 2 diabetes; both caffeinated and decaffeinated coffee produced similar results, suggesting that the non-caffeine components of coffee may be responsible for this effect. Other studies done among Americans and Finnish subjects also showed the lack of correlation between caffeine consumption and cardiovascular complications like heart disease or stroke among diabetics.
While studies in the past have shown that the effects of caffeine have both good and bad sides, its long term effects in diabetics still have to be proven. Health risks of coffee drinking that have been shown such as increases in heart rate, blood pressure, blood sugar levels and insulin resistance are mostly temporary and not necessarily associated with permanent complications like cardiovascular disease, stroke or mortality. As with other chemicals, drugs and foods that are approved for daily consumption, moderation must be taken to avoid the undesirable side effects.
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Lesley L Moisey, et al, “Caffeinated coffee consumption impairs blood glucose homeostasis in response to high and low glycemic index meals in healthy men”, http://www.ajcn.org/content/87/5/1254.full.pdf
Weili Zhang, MD, et al, “Coffee Consumption and Risk of Cardiovascular Diseases and All-Cause Mortality among Men with Type 2 Diabetes”, http://care.diabetesjournals.org/content/32/6/1043.full.pdf
James D. Lane, Phd, et al, “Caffeine Impairs Glucose Metabolism in Type 2 Diabetes”, http://care.diabetesjournals.org/content/27/8/2047.full