Vitamin D

Redefining Vitamin D Sufficiency

Based on the Symposium “Shining Light on Vitamin D: What is the Evidence for Redefining Vitamin D Sufficiency?” Chairs: J. Christopher Gallagher, Francis Glorieux Speakers: Roger Bouillon, Chantal Mathieu, JoAnn Manson, Heike Bischoff-Ferrari, Christopher Kovacs Tuesday, October 19, 2010 ASBMR 2010 Toronto, Ontario

Immunomodulation and Vitamin D • Vitamin D is an immune system modulator with multiple effects on different cells • In inflammation, the immune system starts to produce 25-(OH)-D • In the presence of 25-(OH)-D, the macrophages produce greater amounts of bactericidal substances • 25-(OH)-D downregulates inflammatory cytokines and modifies the behaviour of dendritic cells such that they become less proficient at antigen presentation as well as T-lymphocyte activation In animal models: • Vitamin D deficiency is associated with higher infection and autoimmunity rates, and possibly adverse transplant outcomes • Intervention with high doses of 25-(OH)-D has been shown to prevent autoimmune disease, provided it is given before the immune system has been activated

Muscle, Bone Health and Vitamin D • Human muscle tissue has vitamin D receptors (VDRs) that decrease in numbers with age, possibly linking the VDR to age-related sarcopenia

Vitamin D: – Appears to stimulate muscle protein in postmenopausal women with OP – Deficiency causes osteomalacia, characterized by muscle weakness, pain and a waddling gait that is reversible with treatment – A meta-analysis of 12 RCTs (n>31,000, ≥65 years of age) showed that fracture risk was reduced by 14% for non-vertebral fractures and 30% for hip fractures only in the highest quartile levels of 792 to 2000 IU/day • High doses of vitamin D supplementation have been shown to significantly 3 in seniors ≥65 years of age and the protective effect reduce fall-related injuries occurs in 30 nmol/L • Infants are born with 25-(OH)-D levels that are between 75 and 100% of maternal levels

Vitamin D in Lactation • There is a 5-10% loss of BMD between end of pregnancy and end of lactation but it returns to baseline BMD within 3 to 12 months • Maternal 25-(OH)-D levels do not change during lactation and there is no evidence that mothers require more vitamin D to maintain a given level • Even very high doses of vitamin D during lactation have no effect on breast milk calcium content • During lactation, the mother’s 25-(OH)-D levels do not affect the baby (unless very high) because little goes into the milk • Breast-fed babies require supplemental vitamin D at a dose of 200 to 300 IU/day • Formula-fed babies should be getting enough vitamin D in the formula

What level of 25-(OH)-D is necessary to maintain health?

Deficient: