A new study published in the journal Toxins found that patients with multiple sclerosis had higher vitamin D-binding protein levels than healthy participants.
Multiple sclerosis (MS) is a disease of the central nervous system in which your immune system attacks the protective sheath that surrounds your nerves. This damage disrupts the ability of your brain to communicate with the rest of your body.
Research has revealed vitamin D deficiency to be an environmental factor involved in the development MS, and higher levels of circulating vitamin D are related to a reduced risk of developing MS and a reduced risk of relapsing. While there is substantial evidence for a role of vitamin D in multiple sclerosis, the relationship between MS and vitamin D binding protein (DBP) remains unclear.
As the name suggests, DBP binds to vitamin D and transports it to target tissues. Albumin has a similar structure to DBP and can also bind to vitamin D. However, albumin has a lower affinity for it, which binds to vitamin D more loosely. Over 85% of circulating vitamin D is bound to DBP and about 12% to 15% is bound to albumin.
Scientists continue to debate whether DBP bound vitamin D is considered bioavailable vitamin D. The predominant hypothesis believes that only unbound vitamin D can enter cells and become activated vitamin D, and therefore, bound vitamin D is not considered bioavailable. But this hypothesis was challenged by the discovery of receptors that transport vitamin D and DBP complexes into target organs. Additionally, DBP is suggested to help vitamin D access cells in the central nervous system.
Recently, researchers wanted to determine the relationship between MS and the levels of each vitamin D carrier (albumin and DBP). To do this, they measured DBP and albumin levels in 28 remitting MS patients and 24 healthy controls.
Here is what they found:
- MS patients had significantly higher DBP levels than healthy subjects (p = 0.0001).
- When stratified by sex, the significant relationship remained. Males with MS had higher DBP levels than healthy males (p = 0.0080) and females with MS had higher DBP than healthy females (p = 0.0064).
- Those who were undergoing therapy for MS and those who were not undergoing therapy had similar DBP levels to one another.
- There were no significant differences in albumin levels between those with MS and healthy controls.
The researchers concluded,
“Our data, together with results from proteomic studies showing that DBP levels in the cerebrospinal fluid correlate with the MS course, point to a still under-recognized involvement of this protein in MS.”
They went on to add,
“With the present knowledge we cannot anticipate whether vitD bioavailability is enhanced or impaired in remitting MS patients as a consequence of their higher blood DBP levels.”
The significant difference in DBP levels between patients with MS and healthy participants suggests that DBP may hold a greater importance than currently known. Further research is needed to better understand the function of DBP.