From the Guidelines
Vitamin D has a significant impact on bone health, reducing the risk of fractures in older individuals by improving bone density and muscle strength, with a recommended daily dose of 482-770 IU/day or 12.0-19.25 μg/day. The effect of vitamin D on bone health is multifaceted, including the improvement of bone density and quality, as well as the reduction of falls in older individuals by increasing muscle strength 1. According to a meta-analysis of 12 double-blind RCTs, the pooled relative risk for prevention of non-vertebral fractures was 0.86 (95% CI, 0.77-0.96) and 0.91 (95% CI, 0.78-1.05) for the prevention of hip fractures, with significant heterogeneity explained by factors such as dose and achieved blood 25(OH)D levels 1. Key findings from the study include:
- Non-vertebral fractures were reduced by 20% and hip fractures by 18% in trials with a high received dose of vitamin D
- Doses < 400 IU/day did not show any effect, and fracture reduction was only achieved in trials that achieved 25(OH)D levels of at least 30 to 40 ng/ml
- Vitamin D supplementation also reduced the risk of falling in community-dwelling and institutionalized elderly by 13% 1. Overall, maintaining adequate vitamin D levels is essential for optimal bone health, particularly in older adults, and can be achieved through a combination of dietary sources, supplements, and sun exposure.
From the Research
Effects of Vitamin D on Bone Health
- Vitamin D is essential for calcium absorption and bone mineralization, and is positively associated with bone mineral density (BMD) 2.
- Prolonged and severe vitamin D deficiency can lead to rickets in children and osteomalacia in adults, while sub-optimal vitamin D status can contribute to osteoporosis 2, 3, 4.
- Vitamin D supplementation can improve muscle strength, reducing the incidence of falls and subsequent fracture risk 2, 5.
- Vitamin D may also influence fracture risk through its immunoregulatory mechanisms, modulating the effects of pro-inflammatory cytokines on bone health 2.
Mechanisms of Vitamin D in Bone Health
- Vitamin D regulates calcium homeostasis, maintaining serum calcium and phosphorus concentrations within a normal range to promote mineralization of the skeleton 3, 6.
- The active metabolite of vitamin D, 1,25-dihydroxyvitamin D, binds to the vitamin D receptor (VDR) present in nearly all tissues of the human body, exerting paracrine/autocrine actions related to bone metabolism and other diseases 5.
- Vitamin D deficiency can result in secondary hyperparathyroidism, increasing bone resorption and decreasing bone mineral content, while vitamin D sufficiency is essential to maximize bone health throughout life 4, 6.
Importance of Vitamin D for Bone Health
- Adequate vitamin D status, as represented by serum 25-hydroxyvitamin D concentration, protects against osteoporosis by improving bone mineral density and reducing the risk of fracture 6.
- Vitamin D cannot restore bone loss due to increased bone resorption, but it can help prevent bone loss and maintain bone health 4.
- The Endocrine Society Guidelines recommend adequate vitamin D obtained from the sun, foods, and supplements to maintain a circulating concentration of 25-hydroxyvitamin D of at least 30 ng/mL for maximum bone health 4.