Dietary tryptophan and bone in older women: a cross-sectional study — ASN Events
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Dietary tryptophan and bone in older women: a cross-sectional study (#149)

Jasmine R Cleminson 1 , Amanda L Stuart 1 , Julie A Pasco 1 2 3 , Jason M Hodge 1 3 , Lana J Williams 1 3
  1. School of Medicine, Deakin University, Geelong, Victoria, Australia
  2. Melbourne Medical School-Western Precinct, The University of Melbourne, St Albans, Victoria, Australia
  3. Barwon Health, Geelong, Victoria, Australia

Objective/Background: Tryptophan is a nutritionally essential amino acid that is required for the biosynthesis of proteins and vital metabolites such as melatonin, niacin and serotonin. Peripheral serotonin has been found to act on bone remodelling. Associations between dietary tryptophan intake and bone are yet to be explored in population-based samples.

Methods: A sample of 270 women enrolled in the Geelong Osteoporosis Study aged 65+ years was included (age 65-93yr, median 74yr). Dietary information was collected using the Cancer Council of Victoria Dietary Questionnaire for Epidemiological Studies (DQES). Tryptophan levels were calculated (g/day) using NUTTAB in accordance with Food Standards Australia and New Zealand and dichotomised (low/high) according to the median. Bone mineral density (BMD; g/cm2) was measured at the PA-spine and total hip using dual-energy X-ray absorptiometry (Lunar) and Speed of Sound (SOS) and Broadband Ultrasound Attenuation (BUA) measures of bone quality were determined using Quantitative heel ultrasound (QUS). Stiffness Index (SI) was calculated from BUA and SOS. Anthropometry was measured while medication use, physical activity and smoking status were self-reported. Linear regression models were used to test associations between dietary tryptophan and BMD, after adjustment for potential confounders.

Results: Dietary tryptophan intakes ranged from 226 to 2180 g/day (median 822). No associations were detected between high vs low tryptophan intake and BMD (spine; mean ± SD: 1.085±0.214 vs 1.104±0.180 g/cm2, hip: 0.868±0.139 vs 0.861±0.144 g/cm2) or QUS measures (SI: 77.5±16.7 vs 78.9±19.8; BUA: 98.6±14.1 vs 98.4±14.8; SOS: 1542.4±32.3 vs 1546.7±39.7, all p>0.05). 

Conclusion: In these women, no evidence could be identified to support an association between tryptophan intakes and bone. Levels of dietary tryptophan may not contribute to a dysregulation in bone turnover in older women. Given the absence of literature, replication and future studies to investigate underlying mechanisms are warranted.