Other effects of too much caffeine:
- It increases anxiety and disrupts sleep patterns, leading to a vicious cycle of restless sleep, relying on caffeine to help with daytime fatigue, followed by more insomnia.
- Caffeine interacts with some medications, including thyroid medication, psychiatric and depression drugs, the antibiotic Cipro and the heartburn drug Tagamet.
- It increases blood sugar levels, making it harder for those with type 2 diabetes to manage their insulin, according to a number of studies; it also can slightly raise blood pressure. If you have difficulty controlling either your blood pressure or diabetes, switching to decaf may help, says Rob van Dam with Harvard's School of Public Health.
- Caffeine potentially leads to some spinal bone loss in postmenopausal women if they typically drink more than three cups, or 300 mg of caffeine, a day, but don't get enough calcium in their diet, says Linda Massey, emeritus professor of nutrition at Washington State University. An older woman should make sure she gets at least 800 mg of calcium daily — through food or supplements — to offset caffeine's effect on calcium, adds Bess Dawson-Hughes, M.D., director of the Bone Metabolism Laboratory at Tufts University in Boston.
Coffee itself can also mess with your stomach. If you have problems with acid reflux or heartburn, then coffee and even tea might not be right for you.
And if you have high cholesterol and you don't want your coffee adding to the problem, you need to use a paper filter to trap the cafestol, a compound in coffee that raises LDL cholesterol levels, says van Dam.
Here's what you need to know if you have a touchy tummy
- Coffee's not your friend if you're prone to heartburn. Coffee is highly acidic and is irritating to the gastrointestinal tract. Switching to decaf won't help: In fact some research has found that decaf increases stomach acid even more than caffeinated coffee. Neither will switching methods of brewing or roasting. Avoiding coffee is the only solution.
- Caffeine's not your friend if you have acid reflux. Caffeine seems to be the main culprit by relaxing the sphincter muscle that normally keeps stomach acid from bubbling up the esophagus. Decaf coffee has significantly less of a reflux effect, studies have found.
Now, the good news about caffeine (and, of course, coffee)
Caffeine has been shown to protect against a host of problems. Some studies have found that those who drink lots of coffee (but not decaf) seem to be four to eight times less likely to develop Parkinson's disease, according to the NIH's National Institute of Neurological Disorders and Stroke, and "that is more likely to be due to caffeine" than to any nutrients in coffee, says van Dam.
Next page: Some other benefits of coffee. »