A study involving 215,000 patients deserves a blog. Generally, I don’t write on papers looking at vitamin D intake from food, as the amount in food is meaningless. However, a study with this many people may show an association that smaller studies of vitamin D intake would miss.
In a meta-analysis, Dr Gwan Gyu Song and colleagues of the Korea University College of Medicine, found three studies totaling 215,000 patients that observed vitamin D intake and the onset of rheumatoid arthritis. Over 800 of those 215,000 patients eventually developed rheumatoid arthritis or RA. Dr Song also wanted to know if vitamin D levels were related to RA severity and found eight such studies with 2,800 RA patients to review.
RA is an inflammatory arthritis that often leads to destruction of joint cartilage and fusion of the joints. I have previously blogged on a study tying vitamin D to the increased risk of heart disease in RA patients. Sometimes RA “burns out,” usually after it has destroyed the affected joints. About 1% of the world has RA, usually women.
From the prevention studies, Dr Song and colleagues found that individuals with the highest level of intake from food had a 24% lower risk of developing RA. And of the severity studies, seven of the eight studies found the higher the D levels the less the activity. This strongly implies a treatment effect, at least from sunshine, which is likely where 80% of this vitamin D came from.
Although Dr Song and colleagues only called for more studies, I have spoken with enough rheumatologists treating RA to know, while it will not repair destroyed joints, it helps stop the inflammation in many RA patients. In a contradictory anecdote, however, one rheumatologist reported to me that his rheumatism (rheumatism is a non-specific term for medical problems affecting the joints and connective tissue) was sensitive to both the sun and vitamin D; both seeming to worsen his condition. My guess is that he had an active joint infection of some kind, and the vitamin D mobilized the naturally occurring antimicrobials, causing a “war” in his joints and thus more severe pain and swelling.
My advice: for those with RA, get your vitamin D levels up to 80 ng/ml by taking 5,000 to 10,000 IU/day of vitamin D and testing every three months for both adequacy and excess. Then adjust your dosage to the amount needed to maintain 80 ng/ml throughout the course of the year. For serious diseases, like RA, which can kill via excessive inflammation, I always recommend high normal levels to be sure the immune system has all the building blocks it needs. I also recommend sunshine or low-pressure sunbeds, as we all know UV radiation does more for the immune system then just make vitamin D.