Dietary changes favorably affect bone remodeling in older adults

Abstract

Objective: To determine whether dietary counseling to increase milk intake could produce useful changes in the calcium economy and what, if any, other nutrition-related changes might be produced. Design: Randomized, open trial. Subjects/setting: Two hundred four healthy men and women, aged 55 to 85 years, who habitually consumed fewer than 1.5 servings of dairy foods per day. Six academic health centers in the United States. Intervention: Subjects were instructed to consume 3 servings per day of nonfat milk or 1% milk as a part of their daily diets, or to maintain their usual diets, for a 12-week intervention period, which followed 4 weeks of baseline observations. Main outcome measures: Energy and nutrient intake assessed from milk intake logs and 3-day food records; serum calciotrophic hormone levels at baseline and at 8 and 12 weeks; urinary excretion of calcium and N-telopeptide at 12 weeks. Statistical analyses: Repeated-measures analysis of variance. Results: In the milk-supplemented group, calcium intake increased by 729±45 mg/day (mean±standard error), serum parathyroid hormone level decreased by approximately 9%, and urinary excretion of N-telopeptide, a bone resorption marker, decreased by 13%. Urine calcium excretion increased in milk- supplemented subjects by 21±7.6 mg/day (mean±standard error), less than half the amount predicted to be absorbed from the increment in calcium intake. All of these changes were significantly different from baseline values in the milk group and from the corresponding changes in the control group. Bone-specific alkaline phosphatase level (a bone formation marker) fell by approximately 9% in both groups. Serum level of insulin-like growth factor-1 (IGF-1) rose by 10% in the milk group (P