Study: Vitamin D improves physical and psychological parameters in early osteoarthritis

By Nikki Hancocks

- Last updated on GMT

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Getty | wavebreak media

Related tags Vitamin d Osteoarthritis Cognitive health

Research has found that early knee osteoarthritis patients with lower vitamin D levels showed higher levels of pain intensity, disability, and anxiety, as well as poorer social participation.

Osteoarthritis (OA) is defined as a common joint condition that typically causes chronic pain and is one of the greatest causes of disability worldwide​. Although some theories regarding the pathogenesis of OA do exist, the exact mechanism is not well charted​.The most frequent nutritional deficiency worldwide is vitamin D deficiency​.

It is well known that vitamin D has an important influence on the state of many articular structures, such as cartilage and subchondral bone, as well as muscle tissues, all of which play a part in the progression of knee OA.

Similarly, parathyroid hormone levels (PTH) could play an important role in the loss and formation of bone and these levels have been related to subchondral bone remodelling, and consequently, to the radiological and clinical progression of knee OA​.

In relation to this, previous studies​ suggest that vitamin D could stimulate proteoglycan synthesis in mature chondrocytes through a metabolic transformation via vitamin D receptors.

It has been suggested​ that vitamin D supplementation could be able to prevent the progression of OA by increasing bone re-modelling and also by reducing the abnormal pathophysiological process.Most of the studies that have reported a link between vitamin D and OA have been conducted in patients with advanced stages of the disease; however, little is understood regarding the effect that vitamin D and PTH could have on the initiation and progression of EOA.

Therefore, the aim of the current cross-sectional study was to study the association of serum concentrations of vitamin D with knee EOA. The secondary objective was to determine the association of serum concentrations of PTH with knee EOA and to determine the relationship between vitamin D deficiency, PTH level, and pain intensity, disability, psychological, and functional variables in patients with knee EOA.

The study

A cross-sectional study with a non-probabilistic sample was designed. A total of 48 EOA patients (and 48 matched controls, mean age of 51.81 ± 5.59, 39 men and 58 women) were recruited at Hospital La Fe, Valencia, Spain.Blood samples were taken to measure vitamin D levels. To measure pain intensity, the Visual Analogue Scale (VAS) was used.  The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaire is self-administered and is used to assess OA disability. 

The five-time sit-to-stand test was employed to assess functional capacity. The subjects also carried out walking speed tests.

To assess their psychological variables, the Hospital Anxiety and Depression Scale (HADS) was used and the Maastricht Social Participation Profile was used to assess social participation.


Patients with EOA showed lower vitamin D levels (22.3 ± 7.3 ng/mL) in comparison to matched controls (29.31 ± 9.2 ng/mL), showing statistically significant differences between groups.

The 48 patients with EOA were divided according to their vitamin D levels. In total, 26 participants presented deficiency in their levels (<20 ng/mL) and 22 presented higher values of 20 ng/mL.

When it came to pain intensity levels, the t-test showed statistically significant differences, showing higher levels of pain intensity in patients with lower vitamin D levels. Similarly, statistically significant differences were found in the WOMAC values with a higher score in the deficient group.

The t-test showed statistically significant differences for sit-to-stand and walking speed, showing poorer values for patients with vitamin D deficiency.

Finally, regarding psychological variables, patients with vitamin D deficiency showed statistically significant differences for anxiety and depression in comparison to patients with higher vitamin D levels. In relation to social participation, statistically significant differences were also found, with lower levels for patients with vitamin D deficiency.

The research concludes: "EOA patients showed statistically significant lower levels of vitamin D than matched controls, but not PTH levels. It was also found that vitamin D deficiency had a statistically significant relationship with a higher level of pain intensity, disability, anxiety, and depressive symptoms, and lower social participation and physical performance. A lower PTH level is associated with higher pain intensity and lower social participation."

The authors note that their results on the relationship with social participation bring another factor into play - the level of physical activity.

"It has been shown that most patients with early OA do not follow the recommendations from the Centers for Disease Control and Prevention and the American College of Sports Medicine for physical activity. Higher increases of the self-reported or objective level of physical activity are associated with a higher increase of vitamin D, and participation in physical activity may increase the opportunity for sun exposure. 

"Similarly, the practice of physical training has been shown to increase the concentration of PTH​. Future studies should focus on the interaction between the vitamin D concentration, PTH level, and the level of physical activity in patients with EOA."

They note that limitations of the study include the inability to confirm cause and effect and the inclusion of only white Spanish participants.

Mechanism of action

Vitamin D has been shown to influence the nociceptive pathway. Tague et al.​ found that vitamin D deficiency leads to hyperinnervation by nociceptors and hypersensitivity of mice skeletal muscles. Lower levels of vitamin D are associated with higher mechanical sensitivity​ in patients with chronic pain.

Roesel hypothesised​ that a vitamin-D deficiency state might alter the functioning of descending inhibitory control pathways. It also seems to have anti-inflammatory properties​.

Amer and Quayyum​ found an inverse relationship between vitamin D and C-reactive protein in participants with a low level of vitamin D. Similarly, Sun et al.​ showed that PTH attenuates OA pain by inhibiting subchondral sensory innervation, suggesting a critical role of PTH in OA pain.

Nevertheless, the authors of the current study note that it is necessary to highlight that pain perception is a multifactorial experience involving the biological body state, cognitive and motivational-affective state, and the context of the individual. They say future studies should therefore interpret our results on vitamin D deficiency and PTH only as possible factors involved in the complexity of chronic pain.

Source: Nutrients

Alabajos-Cea, A.; Herrero-Manley, L.; Suso-Martí, L.; Viosca-Herrero, E.; Cuenca-Martínez, F.; Varangot-Reille, C.; Blanco-Díaz, M.; Calatayud, J.; Casaña, J. 

"The Role of Vitamin D in Early Knee Osteoarthritis and Its Relationship with Their Physical and Psychological Status"

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