In recent years, several studies have generated contradictory results regarding caffeine intake and bone loss in postmenopausal women, creating concern among many women who consume caffeine-containing foods and beverages.

The most recent study found that caffeine consumption is not a risk factor for bone loss in postmenopausal women. The study, "Dietary Caffeine Intake and Bone Status of Postmenopausal Women," was conducted at the Pennsylvania State University's Milton S. Hershey Medical Center and published in the June 1997 issue of the American Journal of Clinical Nutrition.

Although the study was conducted with older women, Tom Lloyd, Ph.D., principal investigator of the study, stresses that the research observed healthy women concerned with maintaining lifelong good health. The study's objective of determining "the effect of long-term habitual dietary caffeine intake on bone status in healthy postmenopausal women" is applicable to a lifestyle choice usually made at an early age—caffeine consumption.

The study observed 138 postmenopausal Caucasian women ages 55-70. The women were divided into three groups according to their caffeine intake from various sources, which was measured as equivalents to a cup of coffee: low (0-2 cups per day), moderate (3-4 cups per day) and high (5 or more cups per day). Unlike previous studies on caffeine and bone mass, in addition to calculating caffeine intake based on computer analysis of consumption diaries, gas chromatography was used on a sample of each subject's brewed coffee beverage to assure an accurate measurement of intake.

The 138 women chosen were healthy and were carefully screened so that factors known to affect bone health, such as smoking, alcohol intake, body weight, physical activity, calcium and nutrient intakes and hormone replacement therapy, could be controlled.

The study measured the women's bone density of the entire body including both hips. Densities were plotted against caffeine consumption. The correlation analysis concluded that caffeine consumption at any level is not associated with changes in bone mass. To explore the possibility that caffeine might have an effect on individuals with lower daily calcium intakes, the sample was divided into thirds according to calcium consumption. The results: At none of the calcium levels was there a correlation between caffeine intake and bone density change. Even adjusting for age, weight and activity level, Lloyd said, "caffeine intake was not associated with any bone mineral measurement."