The interrelationships of calcium and vitamin A and D intakes on bone in a swine model

Hypotheses: We hypothesize that excessive vitamin A, especially in combination with vitamin D deficiency will lead to bone abnormalities, and these effects will be rescued by providing excess dietary calcium.Supporting Objectives-The proposed studies have two overarching objectives that will use innovative methods to assess:1) The interactions of non-optimal (deficient or excessive) vitamin A and D statuses on growth and bone development in young growing pigs.We will measure bone turnover biomarkers, growth, and quality by dual-energy X-ray absorptiometry (DXA) and clinical-computed tomography (CT) of pigs fed combinations of deficient or excessive levels of vitamins A and D.We will determine how vitamin D deficiency and hypervitaminosis interact with excessive levels of vitamin A to worsen or mitigate its impact on bone metabolism.2) The effect of suboptimal (deficient or excessive) dietary vitamin A on a background of adequate and excessive calcium intake.We will modulate dietary vitamin A and calcium to determine changes in detrimental or protective clinical outcomes in growing pigs. Adequate vitamin D will be provided.These studies could prove to be relevant in animals due to the tendency of commercial swine feed manufacturers to add nutrients at levels far above NRC recommendations, and in humans where overlapping interventions for vitamin A deficiency and excessive intake of preformed retinol due to supplements and fortification can lead to hypervitaminosis A. Balancing vitamins A and D and calcium are important food safety consideration.