According to research presented at this week’s American College of Rheumatology meeting in Boston, low vitamin D levels resulted in greater knee pain and difficulty in walking in patients with knee osteoarthritis.

In this 2 year trial on the benefits of vitamin D supplements on knee osteoarthritis progression, researchers studied 65 women and 25 men in their 60’s with knee osteoarthritis. They took baseline measurements of the participant’s blood levels of vitamin D, amount of knee pain, chair rise time and time to walk 20 meters.

The initial analysis showed that 47 percent were vitamin D deficient, having levels below 30 ng/ml. The researchers found that the deficiency was responsible for increased pain and difficulty walking but not chair rise time.

Vitamin D absorption from food and conversion to the active form becomes less efficient with age. While vitamin D supplements are recommended to prevent osteoporosis, this study suggests that vitamin D supplements may be beneficial for arthritis.

Some natural sources of vitamin D include fish oil (see our article on fish oil), liver, dairy products and fortified breakfast cereals. Exposure to sunlight also helps with vitamin D.

This study confirms the results prior studies.

In a study completed in 2004, 221 elderly patients with osteoarthritis of the knee were followed for 30 months. Nearly half of this group had a vitamin D deficiency. Over the test period their vitamin D deficiency was corrected and their disability scores as measured on the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) disability scale improved by 20%. The WOMAC is used to assess patients with osteoarthritis using 24 parameters.

Another 2004 study on 556 patients averaging over 70 years of age found that the risk of progression of osteoarthritis of the knee increased by 300% for those with vitamin D deficiency.

These findings taken together highlight the importance of ensuring adequate vitamin D, either by modification of diet or through supplementation.