PhD Oral Defense: Vitamin D Recommendations for Canadian Elderly: An evaluation of adequacy of current clinical practices for nutrition and skeletal health
PhD Oral Defense of Isabelle Germain, School of Dietetics and Human Nutrition
Vitamin D is a key nutrient in maintenance of calcium homeostasis and contribution to bone health. Elderly populations living in long-term care (LTC) facilities of Canada face a higher risk of deficiency vitamin D intakes and sunlight exposure are limited. Endogenous synthesis and food intake of vitamin D can be cumulatively measured by serum 25-hydroxyvitamin D concentration (25(OH)D). The Institute of Medicine (IOM) revised the Dietary Reference Intakes (DRI) for Vitamin D and Calcium in 2011. The new DRIs replaced the Adequate Intake (AI) of 600 IU/d for vitamin D in adults with an Estimated Average Requirements (EAR: 400 IU/d) and a Recommended Dietary Allowance (RDA: 800 IU/d) for the elderly population of more than 70 y. Regardless of these recommendations, many elderly in Canada, in the community or in LTC, have low vitamin D status. Aging men are underrepresented in research looking at vitamin D and bone health. As men are living longer, and since they experience the highest morbidity and mortality following fractures, more investigation is required to describe the impact of low vitamin D status and its correction on bone health outcomes in advanced aging in men.
The global objectives of this thesis were to: (1) comprehensively assess dietary and supplemental intakes of vitamin D and its association with biomarkers of bone health in elderly men living in a LTC facility of the Montreal region (46°); (2) assess the impact of an 8-week supplementation regimen of 2000 IU/d of vitamin D3 on 25(OH)D and markers of bone metabolism; (3) determine how much vitamin D3 is required to sustain vitamin D status, using vitamin D3 fortified foods.