Dietary changes favorably affect bone remodeling in older adults

Objective To determine whether dietary counseling to increase milk intake c ould 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 year s, 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 nonf at milk or 1% milk as a part of their daily diets, or to maintain their usu al diets, for a 12-week intervention period, which followed 4 weeks of base line 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 1 2 weeks. Statistical analyses Repeated-measures analysis of variance. Results In the milk-supplemented group, calcium intake increased by 729+/-4 5 mg/day (mean+/-standard error), serum parathyroid hormone level decreased by approximately 9%, and urinary excretion of N-telopeptide, a bone resorp tion marker, decreased by 13%. Urine calcium excretion increased in milk-su pplemented subjects by 21+/-7.6 mg/day (mean+/-standard error), less than h alf the amount predicted to be absorbed from the increment in calcium intak e. AU of these changes mere significantly different from baseline values in the milk:group and from the corresponding changes in the control group. Bo ne-specific alkaline phosphatase level (a bone formation marker) fell by ap proximately 9% in both groups. Serum level of insulin-like growth factor-1 (IGF-1) rose by 10% in the milk group (P<.001), and the level of insulin-li ke growth factor binding protein-4 (IGFBP-4) fell slightly (1.9%) in the mi lk group and rose significantly (7.9%) in the control group (P<.05). Applications/conclusions The changes observed in the calcium economy throug h consumption of food sources of calcium are similar in kind and extent to those reported previously for calcium supplement tablets. The increase in I GF-1 level and the decrease in IBFBP-4 level are new observations that are beneficial for bone health. Important improvements in skeletal metabolism c an feasibly occur in older adults by consumption of food sources of calcium . Dietitians can be confident that food works, and that desired calcium int akes can be achieved using food sources.