Lupus patients show more severe symptoms of the disease if their vitamin D levels are low, an Australian first study has found.

Systemic lupus erythematosus (SLE), which affects more than five million people worldwide, was found to be worse in vitamin D deficient SLE patients than in those with normal levels, in the study led by Professor Eric Morand, head of the Monash Lupus Clinic and Southern Clinical School at Monash Medical Centre.

The research also observed that Australians are more susceptible to the disease due to environmental, genetic and cultural factors, which contribute to vitamin D deficiency.

Professor Morand said although practicing sun avoidance is important for lupus patients, as sunlight can make aspects of the disease worse, this can lead to vitamin D deficiency and an increase in the severity of the disease.

“In multicultural Australia, instances of vitamin D deficiency can be seen in cultural groups where clothing covers the body, in people with dark skin tone who have lower absorption, and those who practice sun avoidance” Professor Morand said.

“Although it’s too soon to draw conclusions about the long-term safety and effectiveness of vitamin D supplements in lupus, a clinical trial is the next step proving that supplementing vitamin D makes lupus better.”

For Professor Morand, the battle to find new treatments carries added significance. His sister Maxine Morand, CEO of Breast Cancer Network Australia, was diagnosed with lupus more than 20 years ago, coincidentally around the same time he started researching the disease.

Ms Morand, a former nurse and Victorian Minister, said she was just 26 when she discovered she had the autoimmune disease, meaning the body's immune system attacks itself.

“As a patient with vitamin D deficiency, I’m fascinated by these findings,” Ms Morand said.

“If it can be proved that vitamin D supplementation improves outcomes for the patient and reduces symptoms, then it could significantly improve their quality of life.”

For Ms Morand, symptoms include bouts of extreme tiredness, hair loss, skin rashes and sun-intolerance.

The findings will be presented at the Annual Scientific Meeting of the Australian Rheumatology Association in Canberra from 11 to 15 May, coinciding with the observance of World Lupus Day on 10 May.

The research involved five years of clinical data and blood sample collection from the Monash Lupus Clinic at Monash Medical Centre, the only lupus-dedicated clinic in Australia.