Dietary acid load and bone turnover during long-duration spaceflight and bed rest
| Autor: | Barbara L. Rice, Sara R. Zwart, Holly Dlouhy, Linda Shackelford, Scott M. Smith, Matthew D Koslovsky, Martina Heer |
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| Rok vydání: | 2018 |
| Předmět: |
Adult
Male 0301 basic medicine Bone density medicine.medical_treatment Medicine (miscellaneous) chemistry.chemical_element 030209 endocrinology & metabolism Urine Calcium Spaceflight Bed rest Bone and Bones Collagen Type I Bone resorption Bone remodeling law.invention 03 medical and health sciences 0302 clinical medicine Animal science Bone Density law Humans Medicine 030109 nutrition & dietetics Nutrition and Dietetics business.industry Middle Aged Space Flight Urinary calcium Diet chemistry Potassium Female Dietary Proteins Peptides business Acids Bed Rest Food Analysis |
| Zdroj: | The American Journal of Clinical Nutrition. 107:834-844 |
| ISSN: | 0002-9165 |
| Popis: | Background Bed rest studies document that a lower dietary acid load is associated with lower bone resorption. Objective We tested the effect of dietary acid load on bone metabolism during spaceflight. Design Controlled 4-d diets with a high or low animal protein–to-potassium (APro:K) ratio (High and Low diets, respectively) were given to 17 astronauts before and during spaceflight. Each astronaut had 1 High and 1 Low diet session before flight and 2 High and 2 Low sessions during flight, in addition to a 4-d session around flight day 30 (FD30), when crew members were to consume their typical in-flight intake. At the end of each session, blood and urine samples were collected. Calcium, total protein, energy, and sodium were maintained in each crew member's preflight and in-flight controlled diets. Results Relative to preflight values, N-telopeptide (NTX) and urinary calcium were higher during flight, and bone-specific alkaline phosphatase (BSAP) was higher toward the end of flight. The High and Low diets did not affect NTX, BSAP, or urinary calcium. Dietary sulfur and age were significantly associated with changes in NTX. Dietary sodium and flight day were significantly associated with urinary calcium during flight. The net endogenous acid production (NEAP) estimated from the typical dietary intake at FD30 was associated with loss of bone mineral content in the lumbar spine after the mission. The results were compared with data from a 70-d bed rest study, in which control (but not exercising) subjects’ APro:K was associated with higher NTX during bed rest. Conclusions Long-term lowering of NEAP by increasing vegetable and fruit intake may protect against changes in loss of bone mineral content during spaceflight when adequate calcium is consumed, particularly if resistive exercise is not being performed. This trial was registered at clinicaltrials.gov as NCT01713634. |
| Databáze: | OpenAIRE |
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