Don't worry too much if you can't stop jonesing for java.
 
'There's no proven link between caffeine and heart disease or cancer as long as you stay under six cups of coffee per day,' says C. Noel Bairey Merz, MD, director of the preventive and rehabilitative cardiac center at Cedars-Sinai Medical Center in Los Angeles. Even better, long-term coffee consumption may reduce your risk of type 2 diabetes. And an alkaloid in coffee may prevent cavities. However, more than 300 mg of caffeine a day combined with insufficient calcium could contribute to bone loss, so coffee, tea, and cola drinkers should compensate with a calcium supplement. The final word on caffeine from one bone-health and nutrition expert: 'Stick to two cups a day, and add milk for the calcium,' advises Jasminka Ilich-Ernst, PhD, an associate professor of nutrition at Florida State University.