Kan. News reports about caffeine can be confusing, even though concerns about the popular stimulant are not new, said Karen Hudson, K-State Research and Extension nutrition educator, who also is a registered dietitian.
Caffeine is a mild stimulant that affects the nervous system.
The Chinese have been brewing tea that contained it for centuries. The American Medical Association defines moderate as 200-300 mg a day, which would be equivalent to the amount of caffeine in one to two cups of coffee. Pregnant women and older adults may be more sensitive to caffeine. Caffeine can raise blood pressure and the heart rate temporarily. The rise is similar to an elevation that may result from normal activities, like climbing stairs.