Vitamin D, the anti-rheumatic vitamin

Rheumatoid arthritis is a disease in which joints become inflamed. Hands, wrists, ankles and feet can become painful, swollen or stiff, making it difficult to stretch. Although doctors are becoming increasingly successful at controlling the progression of rheumatism, as rheumatoid arthritis is commonly known, with medication and improving the quality of life of rheumatism patients, they are not yet able to cure the disease.

Health scientists have been studying the effect of lifestyle on the development and progression of rheumatism for many years. Their research shows that a healthy lifestyle with responsible exercise and a good diet cannot prevent rheumatism, but it can reduce the risk of developing the condition.

A good vitamin D level is one of the lifestyle factors that reduces the risk of rheumatoid arthritis and, in people who have rheumatism, alleviates the severity of the disease.

In rheumatoid arthritis, the immune system mistakenly attacks the tissues in the joints. The risk of developing an autoimmune disease such as rheumatism, as well as the severity of its consequences, is lower if there is sufficient vitamin D in the body. After all, the immune system also needs vitamin D to function properly. Immunologists refer to this as the “tolerogenic effect of vitamin D”.

Epidemiological studies suggest that relatively high vitamin D levels reduce the risk of developing rheumatism by 24 per cent. According to these studies, the average vitamin D level in rheumatism patients is 16.5 nmol/L lower than in people without rheumatism. The same studies show that rheumatism is less severe when there is more vitamin D in the blood of rheumatism patients.

Such data are promising but do not yet provide proof. It is conceivable that healthy people or people with relatively mild symptoms of the disease are able to move more easily, so they go outside more often and have higher vitamin D levels due to exposure to sunlight.

However, there are also studies in which researchers have given vitamin D to test subjects. The results of such research are more telling. A recent study that fits this description is the study published in the BMJ in 2022, in which a total of more than 25,000 people over the age of 50 participated as test subjects. Some of the test subjects took a daily supplement of 2000 IU of vitamin D3 for more than five years, while others took a placebo. In the former group, vitamin D levels increased. After one year of supplementation, those levels had risen from an average of 74 nmol/L to 104 nmol/L. (The initial value was already relatively high. The study was conducted in a region with high levels of sunshine.)

During the study, 155 subjects in the placebo group developed an autoimmune disease such as rheumatoid arthritis. In the supplementation group, there were 123. This difference was statistically significant. This implies that an increase in vitamin D levels through vitamin D supplementation reduces the risk of autoimmune disease by 22 percent.

When the researchers looked at rheumatism separately, they found that the subjects in the vitamin D group were 42 percent less likely to develop rheumatism than the subjects in the other group. However, this difference was not statistically significant.

There is more clarity when it comes to the effect of increasing vitamin D levels through supplements in people who have been diagnosed with rheumatoid arthritis by doctors. In 2020, researchers at Tianjin University in China summarised the results of six previously published studies and concluded that rheumatism patients experienced less pain in their daily lives thanks to extra vitamin D. Patients who received vitamin D supplements also reported that their joints were less painful.