Can Vitamin D help prevent the onset ofosteoarthritis (OA)or slow joint damage if you already have OA? While study results have been mixed, in general, they suggest that Vitamin D may be protective in OA.
Vitamin D promotes calcium absorption by the body to enable bone growth and repair. Because osteoarthritis has a bone growth component, researchers have been examining the potential role of vitamin D in osteoarthritis development and progression.
What the Studies Show
Two studies published in 2014 looked at vitamin D levels in the blood of people with or at risk of OA. A study published inThe Journal of Nutritionfound that participants with low vitamin D levels had a more than 2-fold elevated risk of knee OA progression compared with those with greater vitamin D concentrations. The other, published inAnnals of Rheumatic Diseases,发现在老年人中，中度维生素D缺乏预示着5年后新的或恶化的膝盖疼痛。
A third 2014 study published inArthritis Care and Researchasked more than 2,000 people with knee osteoarthritis about their milk consumption during the prior year. They found that those with the self-reported highest milk intake (7 or more glasses per week) had the least amount of joint-space narrowing (a measure of OA progression). This study did not, however, measure blood levels of vitamin D, so there is no way to know if it was vitamin D, another component of milk or an unrelated factor that influenced OA progression.
High-quality controlled trials, however, show less definitive results.
One randomized, controlled trial of vitamin D and OA was published in 2013 inClinical Orthopaedics and Related Research. Scientists in India separated 107 people with knee OA and vitamin D deficiency into two groups: one group received supplements and the other did not. After 1 year, the researchers found a small decrease in knee pain and an improvement in knee function among the vitamin D-treated group, but not the placebo group.
Another randomized, controlled trial – published inJAMA在2013年，没有发现保护关系。研究人员对146名膝骨性关节炎患者进行了为期2年的研究，其中一半人服用了维生素D补充剂。When compared with the placebo group, the supplemented group did not have improved knee pain or less cartilage loss.
Lead study author Timothy McAlindon, chief of the division of rheumatology at Tufts Medical Center in Boston, believes the different results may have been that the India study looked at people with knee OA who were medically deficient in Vitamin D. The participants in McAlindon’s study had normal vitamin D levels to begin with and were getting an extra boost. The scientists in India weren’t just enhancing the participants’ levels, they were replacing a true deficiency.
Getting Enough Vitamin D
当太阳的紫外线B (UVB)直接(而不是通过窗户)到达皮肤时，人体自然合成维生素D。维生素D合成所需的日照时间取决于几个因素:肤色、季节、离赤道的距离以及暴露在阳光下的皮肤数量。在美国南部，穿着背心和短裤的浅色皮肤的人每天可能只需要在阳光下晒10分钟。生活在加拿大的深色皮肤的人可能无法获得足够的中波紫外线来产生足够的维生素D。尽管太阳对维生素D的合成很重要，但减少皮肤暴露在紫外线下以降低患皮肤癌的风险是明智的。
Vitamin D can be consumedin foods like fatty fish (salmon, tuna, mackerel) or in fortified products like milk, yogurt and some orange juices. If you’re not getting enough through your food, supplements can be taken.
然而，过量摄入这种脂溶性维生素可能是危险的。以每天推荐的600国际单位维生素D为目标，而不是更多。
The Bottom Line
Dr. McAlindon’s bottom line take on Vitamin D: “Overall, the potential role of vitamin D in preventing the development of or slowing the progression of osteoarthritis is under active investigation. Results are conflicting, hard to interpret and prone to bias. At this point there is no compelling reason to supplement your diet with Vitamin D solely for possible slowing of your OA or reduction of OA symptoms. Getting adequate Vitamin D through sun exposure and your diet are important for general well-being, bone health, osteoporosis prevention and muscle function. In parts of the world where people are medically deficient in Vitamin D, supplementing the diet could potentially help their joint symptoms along with their overall health.”
Related Resources:
- Learn More About Treatment for Osteoarthritis
- Studies Show Botox May Ease Osteoarthritis Pain
- Can Lifestyle Factors Influence Osteoarthritis Outcomes?