London, Patients with lupus are more likely to have metabolic syndrome and insulin resistance -- both factors linked to heart disease -- if they have lower vitamin D levels, a new study reveals.
Lupus is an uncommon incurable immune system illness, more common in women, where the immune system is overactive, causing inflammation anywhere in the body.
Researchers believe that boosting vitamin D levels may improve control of these cardiovascular risk factors, as well as improving long-term outcomes for patients with systemic lupus erythematosus (SLE).
"Our results suggest that co-existing physiological abnormalities may contribute to long-term cardiovascular risk early on in SLE," said researcher John A Reynolds, Clinical Senior Lecturer in Rheumatology at the University of Birmingham.
"We found a link between lower levels of vitamin D and metabolic syndrome and insulin resistance. Further studies could confirm whether restoring vitamin D levels helps to reduce these cardiovascular risk factors and improve quality of life for patients with lupus,"Reynolds added.
Given that photosensitivity is a key feature of SLE, the researchers say that a combination of avoiding the sun, using high-factor sunblock and living in more northerly countries may contribute to lower levels of vitamin D in lupus patients.
For the study, published in the journal Rheumatology the team studied vitamin D levels in 1,163 SLE patients across 33 centres in 11 countries.
The researchers note that patients with SLE have an excess cardiovascular risk, up to 50 times that seen in people without the condition -- this cannot be attributed to traditional cardiovascular risk factors, such as high blood pressure or smoking, alone.
The mechanisms underlying the association between high blood pressure and low vitamin D in SLE are not clear, but researchers believe they may be linked to impact of vitamin D deficiency on the renin-angiotensin hormone system, which regulates blood pressure, fluid and electrolyte balance, as well as systemic vascular resistance. (Agency)