The National Institutes of Health Consensus Development Conference on Optimal Calcium Intake brought together experts from many different fields including osteoporosis and bone and dental health, nursing, dietetics, epidemiology, endocrinology, gastroenterology, nephrology, rheumatology, oncology, hypertension, nutrition and public education, and biostatistics, as well as the public, to address the following questions: (1) What is the optimal amount of calcium intake? (2) What are the important cofactors for achieving optimal calcium intake? (3) What are the risks associated with increased levels of calcium intake? (4) What are the best ways to attain optimal calcium intake? (5) What public health strategies are available and needed to implement optimal calcium intake recommendations? and (6) What are the recommendations for future research on calcium intake? The consensus panel concluded that: A large percentage of Americans fail to meet currently recommended guidelines for optimal calcium intake. On the basis of the most current information available, optimal calcium intake is estimated to be 400 mg/day (birth-6 months) to 600 mg/day (6-12 months) in infants; 800 mg/day in young children (1-5 years) and 800-1,200 mg/day for older children (6-10 years); 1,200-1,500 mg/day for adolescents and young adults (11-24 years); 1,000 mg/day for women between 25 and 50 years; 1,200-1,500 mg/day for pregnant or lactating women; and 1,000 mg/day for postmenopausal women on estrogen replacement therapy and 1,500 mg/day for postmenopausal women not on estrogen therapy. Recommended daily intake for men is 1,000 mg/day (25-65 years). For all women and men over 65, daily intake is recommended to be 1,500 mg/day, although further research is needed for this age group. These guidelines are based on calcium from the diet plus any calcium taken in supplemental form. Adequate vitamin D is essential for optimal calcium absorption. Dietary constituents, hormones, drugs, age, and genetic factors influence the amount of calcium required for optimal skeletal health. Calcium intake, up to a total intake of 2,000 mg/day, appears to be safe in most individuals. The preferred source of calcium is through calcium-rich foods such as dairy products. Calcium-fortified foods and calcium supplements are other means by which optimal calcium intake can be reached in those who cannot meet this need by ingesting conventional foods. A unified public health strategy is needed to ensure optimal calcium intake in the American population. The full text of the consensus panel's statement follows.