Higher levels of vitamin D may decrease pain and improve function in obese individuals with the bone disease osteoarthritis, suggests a new research.

The findings published in the journal The Clinical Journal of Pain indicate that adequate vitamin D levels help obese individuals with osteoarthritis walk, balance and rise from sitting to standing position better than those with insufficient vitamin D levels.

"Vitamin D maintains calcium and phosphate concentration levels to keep bones strong," said lead author Toni Glover, assistant professor at the University of Florida College of Nursing.

"Adequate vitamin D may be significant to improving osteoarthritis pain because it affects bone quality and protects cell function to help reduce inflammation," Glover explained.

Increased pain due to osteoarthritis could limit physical activity, including outdoor activity, which would lead to both decreased vitamin D levels and increased obesity, the researcher pointed out.

Osteoarthritis is the most common form of arthritis, affecting millions of people worldwide. For the study, the researchers analysed blood samples for vitamin D levels from a group of 256 middle-aged and older adults.

Among the 126 obese participants, 68 were vitamin D-deficient while only 29 of the 130 non-obese participants were deficient, suggesting obesity is significantly associated with clinically relevant vitamin D deficiency.

The analysis showed that obesity was associated with vitamin D deficiency, knee osteoarthritis pain and poor functional performance. 

Foods rich in vitamin D include salmon, tuna, sardines, shrimp, mushrooms and egg yolks. Foods that may be fortified with vitamin D include milk and some cereals, yoghurt and orange juice.

The body also produces vitamin D through sun exposure.