Vitamin D deficiency is a significant public health problem worldwide due to its crucial role in musculoskeletal health, muscle function, and bone strength. Studies have shown that more than 90% of individuals with musculoskeletal disorders have low levels of 25-hydroxyvitamin D, the standard measure of vitamin D concentration. Vitamin D also has anti-inflammatory properties and helps regulate pain, so low levels are often associated with various chronic pain conditions.
Among these conditions, lower back pain stands out as one of the leading causes of disability worldwide. In 2017, nearly 8% of the global population reported suffering from lower back pain, a number that continues to rise. While factors such as injuries, sedentary lifestyles, genetics, occupational hazards, and psychosocial factors contribute to lower back pain, the potential impact of vitamin D in managing this condition is not yet fully understood.
Previous research indicates that 5% to 10% of cases of low back pain progress to chronic low back pain, persisting for more than 12 weeks, and about 50% of individuals treated for low back pain experience recurrent episodes within a year.
Past studies have also suggested a connection between vitamin D deficiency and lower back pain, as this hormone is crucial for bone health and inflammation regulation. Symptoms of vitamin D deficiency can include bone, joint, and muscle pain.
Now, researchers from the University of Heidelberg in Germany have published a study in the journal Nutrients challenging the previously suggested link between vitamin D deficiency and lower back pain. They reported that there is no correlation between the two.
In this study, researchers analyzed data from the UK Biobank, focusing on 135,934 participants aged 40 to 69 years, recruited from various centers in Scotland, England, and Wales. They had access to information on participants' vitamin D levels, supplement use, and lower back pain diagnoses.
Biomedical data were collected through questionnaires, interviews, physical assessments, and clinical tests on saliva, urine, and blood samples.
Vitamin D status was determined based on serum levels of 25-hydroxyvitamin D, with deficiency defined as levels below 30 nmol per liter, insufficiency as levels between 30 and 50 nmol per liter, and sufficiency as levels above 50 nmol per liter. Information on multivitamin and vitamin D supplement use was obtained from baseline questionnaires.
The researchers obtained lower back pain diagnoses and dates from primary care records. Baseline visit data were used for cross-sectional analysis, while diagnoses during follow-ups were used for longitudinal analysis. Self-reported lower back pain from questionnaires was combined with physicians' diagnoses to determine the exposure variable.
Various covariables that could be associated with vitamin D deficiency were considered, including body mass index, sociodemographic factors, biomarkers, lifestyle factors, and diseases. Factors related to vitamin D levels, such as seasonality, geographic latitude of recruitment centers, and calendar month of blood sample collection, were also included in the analysis.
The analysis revealed that about 21.6% of participants had vitamin D deficiency, and 4% regularly took vitamin D supplements. Approximately 3.8% reported lower back pain in the month before the study, while 3.3% were diagnosed with lower back pain for the first time during a median follow-up of 8.5 years.
Contrary to previous suggestions, the researchers found no association between vitamin D deficiency, supplementation, and lower back pain. They attribute this to the complex nature of lower back pain, which can have multiple contributing factors.
Although the cross-sectional analysis initially showed notable links between lower back pain, serum vitamin D levels, and vitamin D supplement use, these associations lost significance after accounting for various confounding factors. Similarly, the longitudinal analysis found no connections between the use of vitamin D supplements or serum vitamin D levels and the development of lower back pain.
The researchers emphasized that while vitamin D is important for musculoskeletal health and has anti-inflammatory properties, lower back pain can stem from various factors including sedentary lifestyles, injuries, and occupations that require unhealthy postures. Additionally, other health conditions and genetic factors can contribute to lower back pain. Therefore, further research is needed to understand the specific causes of lower back pain and the role of vitamin D in its management.
Previous studies on this topic have yielded mixed results. In July 2018, a study discovered that low back pain severity tended to increase in individuals with a deficiency in vitamin D. Conversely, a study from January 2019 suggested that addressing vitamin D deficiency might lead to improvements in back pain, particularly in overweight or obese individuals.
Another study in August 2019, revealed that both vitamin D deficiency and insufficiency could contribute to or exacerbate neck and back pain.
A study from February 2021 suggested a strong likelihood of vitamin D deficiency in people with nonspecific chronic lower back pain. It also noted a negative correlation between vitamin D levels and the severity of pain.
Despite these findings, other studies have found no association between vitamin D and lower back pain. For example, a study published in December 2020 found no relationship between chronic lower back pain and vitamin D levels. Similarly, research from March 2018 concluded that vitamin D supplementation was not more effective than placebo, no intervention, or other conservative/pharmacological treatments for lower back pain.