Vitamin D and knee osteoarthritis

Marion Hauser, MS, RD

Many patients that come into our clinics for degenerative joint and spine disease, often ask “What can I do nutritionally to help the treatments?” The answer is usually a general guideline toward a more healthy lifestyle that includes a better diet. To combat degenerative disease the body’s immune/healing response will need good food to make new collagen and run the diseased tissue removal/tissue-building regeneration system.

Then we will be asked, “What vitamins can I take?” Again, the answer will be a general recommendation that will help the body’s immune system by providing certain nutrients that help make the building blocks of new tissue and inspire the mechanisms of repair and wound healing. When someone is healing well with our treatments, this usually means that they have nice homeostasis or balance going on in their nutrition. When they come into our clinics with other challenges that may impact good healing, being overweight or underweight, or having other chronic health issues such as type 2 diabetes, then the patient will be given recommendations and suggestions on how to manage these concerns.

Our bottom line is that when it comes to vitamins and supplements, many supplements will help and support medical treatment. But as a stand-alone or “magic bullet treatment” to reverse years of degenerative joint disease, you have to be realistic in what these supplements can and cannot do for you. Vitamin D is an important vitamin for our health and low levels have been associated with various disease states, including osteoarthritis. Yet there is some controversy surrounding the recommendation of vitamin D supplementation for patients with knee osteoarthritis.

Why would there be controversy? Because many studies are asking vitamin D supplementation to do what it really can’t. Reverse years of degenerative joint damage on its own. Other studies are quick to point out that vitamin D deficiency does not cause knee osteoarthritis. Again we are asking vitamin D to do something it cannot, prevent knee osteoarthritis on its own.


In the image above foods rich in vitamin D are displayed: Sardines, salmon, tuna, butter, fortified cereal, cheese, and eggs. Sunlight is also shown.

Let’s get right to the research. Vitamin D is an important vitamin for our health and low levels have been associated with various disease states, including osteoarthritis.

The majority of us can meet our vitamin D needs via the sun and exposure to ultraviolet (UVB) radiation. When people age, they lose the ability to synthesize vitamin D through sun exposure, which puts older people at greater risk for deficiency and the associated diseases.

Vitamin D deficiency and osteoarthritis symptoms have some overlap. Those with osteoarthritis suffer from joint pain, muscle wasting, and decreased motion in their joints, all of which can increase in severity with age. Symptoms of vitamin D deficiency include greater joint pain, poor muscle function, and progression of osteoarthritis.

Will supplementation with Vitamin D help my knee pain?

In many cases, yes. In many cases, no. Studies have shown that Vitamin D supplementation may help to decrease the chronic pain people with osteoarthritis experience. In research we are about to examine, investigators have shown that those suffering from knee osteoarthritis combined with Vitamin D deficiency, had improved muscle strength, better knee function, and reduced pain once they started to take Vitamin D supplementation. This combination resulted in less risk of falls and an overall improved quality of life.

How does Vitamin D help knee pain?

It may have a protective effect on cell function resulting in less inflammation. It also may be that osteoarthritis pain leads to reduced physical activity, including outdoor activity, which would lend to the decreased vitamin D levels from sun exposure.  Since osteoarthritis is the most common cause of musculoskeletal disability and pain worldwide, supplementing with vitamin D can provide a simple, safe, and inexpensive option to consider for reducing pain and improving muscle strength and physical function in those with osteoarthritis.

Vitamin D and knee osteoarthritis

Doctors based out of Victoria University in Australia writing in the September 2017 issue of Archives of Osteoporosis (1) are making a connection between knee osteoarthritis, fall risk, and leg muscle strength in osteoarthritic patients.

Here is what they said and what they were looking to confirm:

  • Low vitamin D status in people with knee osteoarthritis is often reported to be associated with increased pain and locomotor dysfunction (reduced ability to walk).
  • However, despite the growing evidence of the effect of vitamin D on the development and progression of knee osteoarthritis, vitamin D’s role remains conflicting.
  • (Their) study investigated the effect of circulating 25-hydroxyvitamin D (25 (OH) D) on pain, quadriceps strength, lower limb muscle mass, and knee power function during balance recovery in people with knee osteoarthritis.”

Here are their results:

  • Twenty-four participants with clinical symptoms of knee osteoarthritis (who were an average age of about 69 years old) participated in the study.
  • Seven patients (29.1%) were classified as vitamin D-insufficient.
    • These patients demonstrated poorer knee function during balance recovery, greater pain, and locomotor dysfunction.
    • Vitamin D insufficiency may have an adverse effect on muscle power function.

Citing this research was a July 2019 study published in the journal American College of Rheumatology Open Rheumatology (2) which suggested “Given the multiple skeletal and extra skeletal benefits of vitamin D supplementation in elderly people, the issue of vitamin D supplementation in knee osteoarthritis requires further study to elucidate the dosage and duration of treatment that provides the most effective therapeutic effect.” In other words, how much vitamin D and how often? This question can be discussed with your doctors.

Vitamin D, knee osteoarthritis, and bone density

Further, a March 2020 study citing the above research, published in the Mediterranean Journal of Rheumatology (3), suggested an association between the grade level of knee osteoarthritis and vitamin D levels. The researchers observed that low vitamin D intake increases the risk of knee osteoarthritis, (as demonstrated by scans and images) especially when the patient’s bone mineral density (BMD) is low. The researchers wrote: “Improving vitamin D levels in patients may have a protective role against the development of knee osteoarthritis, especially in those patients with low BMD. Further, those with more advanced knee osteoarthritis had lower vitamin D levels.

Postural balance impairment and fall risks are suspected in patients with low vitamin D levels

Staying on topic with fall risks. A November 2021 paper published in the World Journal of Clinical Cases (4) brought attention to the possible links between low vitamin D levels, knee osteoarthritis, postural balance, and fall risks in older patients.

In this study, 105 elderly patients with hip and knee osteoarthritis were examined for vitamin D deficiency. In this group, 43 patients (56.6%) had severe osteoarthritis, while 33 patients (43.4%) had mild or moderate osteoarthritis. The observation was “Patients with vitamin D deficiency showed a higher Lequesne index score (this is an outcome survey which asks patients about the pain, ability to walk, and their ability to perform daily functions linked to quality of life), indicating a worse functional impairment when compared to individuals with normal vitamin D levels. Additionally, patients with vitamin D deficiency had worse postural balance. . . ”

Research: Vitamin D2 Supplementation Improves Quality of Life and Physical Performance in Osteoarthritis Patients

First a brief explanation of the differences between vitamin D2 and vitamin D3. The benefits of both are that supplementation can raise circulating vitamin D levels in your blood. Vitamin D3 is thought to provide more benefit as studies have shown this form of the vitamin can elevate vitamin D blood levels for longer periods of time.

Vitamin D2 supplementation is plant-based. Vitamin D3 is animal-based.

An August 2022 paper (5) confirmed what many researchers believe, that vitamin D3 and a more potent form of vitamin D than D2. “Vitamin D2 and vitamin D3 increased serum vitamin D levels, but doubling the vitamin D2 dose failed to match the better treatment response of vitamin D3. Relying on a vitamin D3 injectable form would be a preferable choice for treating the severe form of vitamin D deficiency in a primary care setting.”

How much vitamin D? A Vitamin D2 study

University researchers in Thailand wrote in the July 2017 edition of the international medical publication Nutrients (6) about how much supplementation would offer benefits to patients:

Here are the highlights of this research:

  • One hundred and seventy-five primary knee osteoarthritis patients with low levels of serum 25(OH)D (<30 ng/mL) received 40,000 IU vitamin D₂ (ergocalciferol) per week for six months.
  • Baseline vitamin D status, 58.90% of patients had vitamin D insufficiency, and 41.10% had vitamin D deficiency.
  • After vitamin D₂ supplementation for six months, 57.10% of patients had vitamin D sufficiency and 42.90% had vitamin D insufficiency.


  • Patient quality of life and pain both improved significantly from baseline to the six-month time point.
  • Knee osteoarthritis patients demonstrated significant improvement in grip strength and physical performance measurements after vitamin D₂ supplementation.
  • Vitamin D₂ supplementation for six months also reduced oxidative protein damage.

Vitamin D3 as an anti-inflammatory

A December 2022 paper in the journal Immunologic Research (7) examined the ability of vitamin D to act as an anti-inflammatory in people with knee osteoarthritis.

In this study, eighty knee osteoarthritis symptoms were assessed over a three-month period in patients suffering from primary knee osteoarthritis. These patients received oral vitamin D3 4000 IU/day. The researchers found that after 3 months of supplementation, patients experienced a significant reduction in pain and increased functionality.  86.7% of patients treated with vitamin D3 responded to treatment. At the end of 3 months, levels of various anti-inflammatory markers indicated vitamin D could promote a good inflammatory response and also act as an anti-inflammatory. The researchers concluded: “Treatment with vitamin D is associated with improvement in pain, as well as stiffness and physical function.”

An October 2023 paper in the medical journal Cureus  (8)  investigated whether deficiency of vitamin D impacted or worsened the severity of knee osteoarthritis. In this Saudi Arabian study, 93 patients with suspected knee osteoarthritis were examined.

  • Obesity was seen as a problem in many patients with 18.3% of patients in grade 2 osteoarthritis and 25.8% of patients in grade 3 knee osteoarthritis.
  • Vitamin D deficiency was seen in 54 (58%) of patients.
  • In cases where knee osteoarthritis was present in both knees, 62% of patients had deficient vitamin D levels.

The researchers concluded: “The findings from this study highlight the importance of monitoring and maintaining adequate vitamin D levels to potentially reduce the risk of knee osteoarthritis and the need for early detection and intervention to manage knee osteoarthritis, particularly in females, older population, and obese adults. ”

The effects of vitamin D supplementation on pain in individuals with knee osteoarthritis are open to interpretation and warrant further investigation.

In the December 2015 edition of The Clinical Journal of Pain (9), a team of researchers led by Dr. Toni L. Glover of the University of Florida, College of Nursing and investigators from the University of Alabama wrote about vitamin D, knee pain and problems associated with obesity in patients with knee osteoarthritis.

This study is part of a larger ongoing project at the University of Florida and the University of Alabama at Birmingham that aims to enhance the understanding of racial/ethnic differences in pain and limitations among individuals with osteoarthritic disease (Understanding Pain and Limitations in OsteoArthritic Disease; UPLOAD).

Here are the highlights of their study:

  • Low levels of vitamin D, measured by serum 25-hydroxyvitamin D (25(OH)D) in older adults and obese individuals are correlated with several negative health conditions, including chronic pain.
  • The study patients consisted of 256 (63% female) racially diverse (55% black/African Americans) middle-aged and older adults (mean age 56.8 y).
  • Results demonstrated that obesity was associated with lower levels of 25-hydroxyvitamin D.
  • Participants with adequate 25-hydroxyvitamin D levels reported significantly less knee osteoarthritis pain compared with participants with deficient or insufficient levels, regardless of obesity status.
  • Furthermore, there was a significant interaction between obesity and serum 25-hydroxyvitamin D levels for lower extremity functional performance, such that obese individuals with adequate serum 25-hydroxyvitamin D levels demonstrated better performance than those obese participants with deficient or insufficient serum 25-hydroxyvitamin D levels.

So what to make of this research?

  • The researchers suggest that the mechanisms by which adequate serum 25-hydroxyvitamin D levels are associated with pain severity and improved function have not been completely discovered.
  • Because of the strong association between 25-hydroxyvitamin D levels and knee osteoarthritis pain, it is reasonable to postulate that vitamin D supplementation may help reduce pain affiliated with the condition.
  • While some studies suggest that vitamin D does not regrow cartilage vitamin D supplementation did improve physical function assessed by a timed 20-meter walk and chair-rise test. In another study vitamin D supplementation in veterans was demonstrated to significantly decrease pain level, number of pain sites, use of pain medication, as well as improve sleep and health-related quality of life.
  • The effects of vitamin D supplementation on pain in individuals with knee osteoarthritis are open to interpretation and warrant further investigation.

After Knee replacement

A May 2021 study in the journal Menopause (10) suggests low vitamin D levels can negatively impact knee replacement. Preoperative vitamin D deficiency may adversely affect early functional outcomes in postmenopausal women after total knee replacement. In addition, vitamin D deficiency, smoking, and high body mass index were independent risk factors for moderate-to-severe knee pain after surgery.

Vitamin D works better if you had no prior knee surgeries

A September 2023 paper in the journal Arthritis Research & therapy (11) aimed to investigate the long-term effect of vitamin D supplementation compared to placebo over 5 years in participants with knee osteoarthritis. The researchers also described the effect of maintaining sufficient serum vitamin D levels over five years for improving symptoms of knee osteoarthritis. The researchers did not find that vitamin D supplementation over 2 years or maintaining vitamin D sufficiency for 5 years was associated with statistically significant differences in change in knee symptom scores over 5 years. However, among study participants who did not report knee surgery, 2-year vitamin D supplementation and maintaining sufficient vitamin D was linked to modest improvements in knee symptoms and depression scores in knee osteoarthritis.

Vitamin D can improve healing and Prolotherapy treatments

Prolotherapy is an injection treatment that in many cases uses simply dextrose to create inflammation. At our center, it is the main treatment option we offer.

In the Journal of Prolotherapy, (12) Margaret E. Taylor, MBBS, BSC, FACNEM, wrote:

  • People who heal well obviously differ in some important way from those who we see with chronic non-healing lesions. The distinguishing feature is primarily the effectiveness of the healing cascade. Unless the factors contributing to this are considered, the outcome of Prolotherapy will also be affected. Research shows the most important nutrients for the generation of new collagen for healing are protein, vitamin C, zinc, copper, and manganese, all cofactors for various enzymes in collagen generation and stability. Nutrition in modern societies is shown to be inadequate in many of these areas and can easily be corrected.
  • Malabsorption is also a cause of poor healing and musculoskeletal difficulties, and undetected celiac disease is common in our patients. Chronic widespread pain is similar but a separate entity, and thyroid and vitamin D deficiency need to be considered.
  • “Unexplained musculoskeletal pains are often due to vitamin D deficiency as well as deconditioning syndrome. (Deconditioning syndrome is when you stop exercising or being active because of an injury or emotional distress). Pains of this type are a recognized symptom of osteomalacia (softening of the bones by the deficiency of vitamin D or calcium) which is diagnosed by tests for calcium, vitamin D, and parathyroid hormone. Supplementation with vitamin D for 1 to 2 months has been shown to normalize muscle strength and pain in patients with myopathy.
  • In 139 patients with muscle pain, 74% were vitamin D deficient, and 90% of those improved with vitamin D.

Vitamin D can help, just don’t ask it to do what it can’t

As the above research points out, vitamin D does have a place in helping a patient with knee osteoarthritis. Vitamin D supplements are readily available and foods rich in vitamin D are plentiful. These include salmon, herring, and sardines, for non-fish lovers spinach and kale. Of course, sunshine helps a lot too.

A study in the Orthopaedic Journal of Sports Medicine (13) from Creighton University School of Medicine concludes this way, and it is a good way to conclude our article:

“Vitamin D-sufficient patients have a lower risk of developing osteoarthritis, and vitamin D sufficiency and supplementation decrease articular cartilage degeneration radiographically (As seen on MRI). Some studies have investigated the effect of vitamin D on osteoarthritis progression and pain management; however, while there is no general consensus on the effects of vitamin D on osteoarthritis, some results seem promising. Vitamin D supplementation may be a safe method to treat and prevent osteoarthritis, but future research is required to define the specific pathway and ultimate efficacy.”

If you have questions about chronic pain, you can get help from our Caring Medical staff.

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