Although many foods and dairy products such as milk, yogurt, eggs and cheese are fortified with vitamin D, many are still lacking adequate amounts, which, according to a new study “Low Vitamin D Linked to Osteoarthritis", published in the July 2015 issue of AgResearch Magazine and funded in part by USDA, may increase your risk of developing the painful condition known as osteoarthritis in your knees.
A team of researchers investigated the possible interaction between circulating blood levels of both vitamin D and parathyroid hormone (PTH), which is involved in vitamin D metabolism, on the progression of knee osteoarthritis in adults.
The scientists looked at a subset of data collected during a longitudinal study called the Osteoarthritis Initiative (OAI)—a large study of individuals with, or at risk of, knee osteoarthritis. The OAI study participants, ages 45 to 79 years, had at least one knee with evidence of osteoarthritis. The researchers focused on a total of 418 volunteers whose blood serum concentrations of vitamin D and PTH were available and whose radiographs to assess knee osteoarthritis progression were available. The volunteers were followed for four years, during which time knee osteoarthritis progression was tracked and related to vitamin D and PTH levels in the blood.
Compared to volunteers with healthy levels, participants with low vitamin D levels—defined as those with less than 15 ng/mL of blood serum—had more than double the risk of their knee osteoarthritis worsening during the study. People who had both low vitamin D and high PTH concentrations were more than three times more likely to get worse during the study than those with normal levels of both.
The scientists concluded vitamin D deficiency is a risk factor for increased knee osteoarthritis progression, and that increased, adequate dietary intake may be beneficial in those with knee osteoarthritis.
These results support the importance of food fortification but they also highlight the need to continue finding new ways to fortify everyday foods and beverages.
