How Vitamin D Influences Bone HealthOften called the “sunshine vitamin” because the body produces it after exposure to ultraviolet rays from the sun, vitamin D has several roles in the maintenance of bones. According to published research, “The main effect of [vitamin D] is to stimulate the absorption of calcium from the gut. The consequences of vitamin D deficiency are secondary hyperparathyroidism and bone loss, leading to osteoporosis and fractures, mineralization defects, which may lead to osteomalacia in the long term, and muscle weakness, causing falls and fractures. Vitamin D status is related to bone mineral density and bone turnover.”1 Simply put, vitamin D aids in the absorption of calcium and also decreases the amount of calcium excreted through the urine. Without calcium’s all-important sidekick, the body would not be able to properly use the calcium you take in through diet and supplementation. This is why so many dairy products and other calcium-rich foods are D-fortified. Vitamin D is also necessary for the proper growth of new bone and breakdown of old bone. Just as importantly, vitamin D helps to support the muscles that we need to avoid falls, which very often lead to broken bones. Countless studies have shown the important relationship between vitamin D and calcium in the prevention of osteoporosis. In one large meta-analysis of 29 studies, researchers concluded that, “Evidence supports the use of calcium, or calcium in combination with vitamin D supplementation, in the preventive treatment of osteoporosis in people aged 50 years or older.” Supplementation was associated with a 12 percent reduced risk of all types of fractures and significantly slower rates of bone loss.
An Epidemic of D DeficiencyIt’s clear that vitamin D is no small player when it comes to osteoporosis prevention and overall bone health. But here’s the problem: So many people are severely deficient in vitamin D! In fact, one study that examined vitamin D levels in dozens of countries around the world and declared it a “global health problem, in all age groups…”5 If you don’t know your vitamin D status, ask your doctor to check. It’s a very simple blood test that most insurance companies cover. I like to see a blood level of at least 50 ng/ml in my patients. If you’re low in vitamin D, your doctor may tell you to spend more time out in the sun and consume more dairy products. But that won’t be enough to get you out of the hole. Deficiencies can only be corrected by supplementing with vitamin D3 (the most effective and bioavailable form of this vitamin). How much vitamin D3 you take really depends on your test result. Some people who are extremely deficient need as much as 10,000 IU per day to regain a healthy level. But generally speaking, most people should be fine taking 5,000 IU per day. (Note: This is higher than the government recommended daily allowance of 600-800 IU per day. With an RDA that low, is there any wonder so many people are deficient?) Also keep in mind that magnesium must be present in order for vitamin D to effectively do its job. Magnesium helps convert vitamin D into its active form so that it can absorb calcium. Most high-quality bone supplements contain all three of these nutrients as well as others involved in the
- Lips P and van Schoor NM. The effect of vitamin D on bone and osteoporosis. Best Pract Res Clin Endocrinol Metab. 2011 Aug;25(4):585-91. Last accessed April 9, 2018.
- Tang BM, et al. Use of calcium or calcium in combination with vitamin D supplementation to prevent fractures and bone loss in people aged 50 years and older: a meta-analysis. Lancet. 2008 Aug 25;370(9588):657-66. Last accessed April 10, 2018.
- Harwood RH, et al. A randomised, controlled comparison of different calcium and vitamin D supplementation regimens in elderly women after hip fracture: The Nottingham Neck of Femur (NONOF) Study. Age Ageing. 2004 Jan;33(1):45-51. Last accessed April 10, 2018.
- Snijder MB, et al. Vitamin D status in relation to one-year risk of recurrent falling in older men and women. J Clin Endocrinol Metab. 2006 Aug;91(8):2980-5. Last accessed April 10, 2018.
- Palacios C and Gonzalez L. Is vitamin D deficiency a major global health problem? J Steroid Biochem Mol Biol. 2014 Oct;144PA:138-45. Last accessed April 10, 2018.