We have known the importance of Vitamin D in bone health for a long time. 7-Dehydrocholesterol is a Vitamin D precursor found abundantly in the skin. It is probably formed as a side-reaction product from the cholesterol-forming metabolism. In the skin, this precursor is converted by ultraviolet light (sunlight) to previtamin D. It is then converted to Vitamin D by two other metabolic pathways in the liver and the kidney.
Vitamin D is also absorbed directly from some of the foods we eat. Fish such as salmon, sardines and tuna are a great source of Vitamin D. Eggs, butter, and some mushrooms are other good sources. In addition, some foods, such as milk, are fortified with Vitamin D. There are also Vitamin D supplements.
A deficiency of Vitamin D leads to poorly calcified bone. In children, this causes Rickets which is rare in Australia. In adults, it leads to osteomalacia, which is softening of the bone.
Vitamin D has also been shown to be critical in the function of a healthy immune system. In a recent blog, I wrote that low Vitamin D levels are a significant risk factor for severe disease and death from Covid.
I want to discuss a recent journal publication1 regarding Vitamin D and osteoarthritis. The article looked at people with knee osteoarthritis and Vitamin D deficiency. As well as looking at pain and functional problems, the study looked as well as inflammatory blood markers. The study concluded that people with knee arthritis had lower levels of Vitamin D. In addition, lower levels of Vitamin D were associated with the severity of symptoms and blood inflammatory markers.
It would therefore seem reasonable to check Vitamin D levels in people with knee arthritis. If the Vitamin D level were low, it would be helpful to supplement the daily intake. Many people take Vitamin D 1000 IU (International Units) daily. However, taking up to 4000 IU per day is safe. The dose would depend on various factors, and I would advise talking with your doctor before taking the higher doses.
In summary, Vitamin D is critical for our general health as well as the health of our bones. Make sure you are getting enough sunlight and that you are getting enough Vitamin D. If not, supplement your Vitamin D intake.
- Vitamin D status is associated with inflammatory biomarkers and clinical symptoms in patients with knee osteoarthritis. Amirkhizi et al. The Knee 36 (2022) 44-52.