From the Guidelines
Taking vitamin D supplements makes sense for many people, especially those with deficiency risk factors, as it can help prevent fractures and falls in community-dwelling adults aged 65 years or older who are at increased risk for falls because of a history of recent falls or vitamin D deficiency. The recommended daily intake is 600-800 IU for most adults, though people with deficiencies may need higher doses (1,000-4,000 IU) as prescribed by a healthcare provider 1. Vitamin D is essential for calcium absorption, bone health, immune function, and may help prevent certain chronic diseases. Risk factors for deficiency include limited sun exposure, darker skin, obesity, age over 65, and certain medical conditions. Before starting supplements, consider getting your vitamin D levels tested to determine if you need them and at what dose. While sunlight exposure helps your body produce vitamin D naturally, many people don't get enough sun or have factors limiting production. Food sources like fatty fish, fortified dairy, and egg yolks provide some vitamin D but often not enough to maintain optimal levels.
Key Considerations
- Vitamin D supplements are generally safe when taken as directed, though excessive doses can cause toxicity with symptoms like nausea, kidney problems, and calcium buildup 1.
- The USPSTF recommends screening for osteoporosis in women aged 65 years or older and in younger women whose fracture risk is equal to or greater than that of a 65-year-old white woman who has no additional risk factors 1.
- Research is needed to determine whether daily supplementation with greater than 400 IU of vitamin D3 and greater than 1000 mg of calcium reduces fracture incidence in postmenopausal women or older men 1.
Potential Harms
- The WHI trial reported an increased risk for nephrolithiasis (hazard ratio, 1.17 [CI, 1.02 to 1.34]) with vitamin D and calcium supplementation 1.
- A meta-analysis of calcium supplementation suggests an association between calcium use and increased risk for cardiovascular disease, but the link has not been consistently demonstrated 1.
From the Research
Vitamin D Supplementation
- The use of vitamin D supplements has increased substantially over the last decade, with epidemiologic evidence linking vitamin D deficiency to various illnesses, including autoimmune disease, cancer, and cardiovascular disease 2.
- The Institute of Medicine has concluded that vitamin D supplementation for indications other than musculoskeletal health is not adequately supported by evidence, and that most North Americans receive sufficient vitamin D from their diet and sun exposure 2.
- However, other studies suggest that vitamin D supplementation may be beneficial for preventing and treating vitamin D deficiency, with a daily dose of 2000 IU (50 µg) considered a simple, effective, and safe dosage for the adult general population 3.
Benefits and Risks of Vitamin D Supplementation
- Vitamin D supplementation in doses of 800-5000 IU/day has been shown to improve musculoskeletal health, reducing the rate of fractures and falls in older adults 2.
- However, single large doses of 300,000-500,000 IU should be avoided, and vitamin D supplementation should not be offered routinely to patient populations without documented deficiency 2.
- The decision to take vitamin D supplements should be made on an individual basis, taking into account factors such as sun exposure, diet, and overall health status 4.
Sun Exposure and Vitamin D
- Sun exposure is an important source of vitamin D, with the skin containing the provitamin D3 7-dehydrocholesterol, a precursor of vitamin D 5.
- However, sun exposure also carries risks, including UV erythema, skin aging, and skin cancer, and the benefits and risks of sun exposure must be carefully balanced 5.
- Official recommendations for vitamin D intake vary by life stage and organization, with some expert groups recommending targeted supplementation for the prevention of specific disorders 6.