New evidence has emerged that vitamin D deficiency might not only be a cause of rheumatoid arthritis but also worsen the severity of the disease.
In a study published in the journal Nutrients in June, researchers from the University of Saskatchewan evaluated the vitamin D status in 116 patients at a community clinic, 60 of them suffering from rheumatic diseases. The researchers found that vitamin D levels were significantly worse in patients suffering from autoimmune rheumatic disease (such as rheumatoid arthritis).
In addition, the researchers found that, among rheumatoid arthritis patients, lower vitamin D levels were directly correlated with more severe symptoms. The effect was so striking that rheumatoid arthoritis patients with low blod levels of vitamin D were actually five times more likely to suffer from active symptoms than patients with higher levels.
An emerging consensus
Rheumatoid arthritis is an autoimmune disorder, meaning that it is characterized by the immune system misidentifying part of the body as a threat and attacking it. In the case of rheumatoid arthritis, the immune system attacks the joints and other bodily tissues.
Vitamin D has been shown to play a critical role in helping regulate the immune system, and low levels have been linked to a higher risk of various autoimmune diseases. For this reason, researchers have suspected for many years that vitamin D might play a role in the development of rheumatoid arthritis. Population studies have supported this hypothesis, such as one published in the journal Environmental Health Perspectives in 2010 which found that women living in the northeastern United States were significantly more likely to develop rheumatoid arthritis than women living in places that get more year-round sunshine.
The body produces its own vitamin D when the skin is exposed to ultraviolet radiation from sunlight, so overall levels of vitamin D deficiency are lower in regions closer to the equator.
A study published in the journal Arthritis and Rheumatism in 2004 suggests that high levels of dietary vitamin D may also help prevent the development of rheumatoid arthritis. The researchers analyzed data from nearly 30,000 women between the ages of 55 and 69 who had participated in the Iowa Women's Health Study and had been followed for 11 years. Study participants were periodically questioned about their health status, eating habits and use of nutritional supplements. Over the course of the decade-long study, 152 of the participants were diagnosed with rheumatoid arthritis.
The researchers found that women with the highest dietary intake of vitamin D were the least likely to have developed rheumatoid arthritis. In contrast, women whose diet included fewer than 200 International Units of vitamin D per day had a 33 percent higher risk of developing the disease than women whose diets included more. These results remain statistically significant even after adjusting for other potential rheumatoid arthritis risk factors, such as smoking and calcium intake.
Get more sunlight
Although certain foods are enriched with vitamin D and the vitamin can also be taken in supplement form, getting more sunlight is still the safest and most effective way to increase your body's levels of this powerful nutrient. Doctors say that your body can produce all the vitamin D it needs from just 15 to 30 minutes per day of skin on the face and hands (without sunscreen) for lighter skinned people, with more time needed for people with darker skin.
And it's not just for reducing your risk of rheumatoid arthritis. Higher levels of vitamin D have been linked to lower rates of various autoimmune diseases, as well as heart disease, diabetes and cancer.
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