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New study suggests vitamin D may help prevent progression of knee joint synovitis

Posted on: March 19, 2017   by  Amber Tovey


A randomized controlled trial published in the journal Osteoarthritis Cartilage found that vitamin D supplementation may halt the progression of knee effusion synovitis.

Knee joint synovitis (KJS) is a type of knee pain typically caused by arthritis, rheumatic disease, sickle cell anemia or an injury. It occurs when the synovium, the special liquid filled membrane that lines the bones and encloses the joints, becomes inflamed or damaged.

The purpose of the synovium is to allow smooth motion by preventing the bones of the leg from grinding together when the knee moves. When the synovium becomes damaged, pain, swelling and stiffness result. The condition can become so severe that the person may have difficulty walking.

The prognosis of KJS depends on the cause of it. Injuries may heal on their own, but if the KJS is caused by arthritis or another degenerative disease, the disease is progressive, leading to further degradation.

Treatment commonly involves pain killers, anti-inflammatory medicine and rest. However, if the KJS is debilitating, surgery may be necessary.

Researchers recently conducted a randomized controlled trial (RCT) to determine the effects of vitamin D supplementation on the effusion-synovitis volume, the size of the synovium that is affected. The researchers included a total of 413 KJS patients with symptomatic knee osteoarthritis and low vitamin D levels (5 ng/ml to 24 ng/ml). Half of the patients were randomly selected to receive 50,000 IU of vitamin D3 monthly, while the other half received a dummy pill monthly. The study lasted for two years.

Knee effusion-synovitis volume was assessed before and after use of vitamin D or the dummy pill. The researchers found that, after two years, the total effusion-synovitis volume significantly increased in those who received the dummy pill. Whereas, the total effusion-synovitis volume remained stable in the vitamin D group. The statistical analysis revealed that those who received vitamin D were 13% less likely to experience an increase in effusion-synovitis volume.

The researchers concluded,

“Vitamin D supplementation could retard the progression of effusion-synovitis, suggesting it can potentially improve outcomes in people with an inflammatory knee OA phenotype.”

It’s important to note that the Vitamin D Council does not advise taking high doses of vitamin D monthly or even weekly. When pharmaceutical doses are given, 25(OH)D goes up for a week or so but then the 24-hydroxylase, the catabolic enzyme, kicks in and lowers 25(OH)D as well as serum 1,25(OH)2D. This lasts for at least 2-3 weeks and will reduce the likelihood of finding a positive response. It is better to get vitamin D daily via sun exposure when possible or via supplements if sun exposure is not an option.


Tovey, A. & Cannell, JJ. New study suggests vitamin D may prevent progression of knee joint synovitis. The Vitamin D Council Blog & Newsletter, March 14, 2017.


Wang, X. et al. Knee effusion-synovitis volume measurement and effects of vitamin D supplementation in patients with knee osteoarthritis. Osteoarthritis Cartilage, 2017.

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