The CYP2R1 gene provides instructions for making an enzyme called 25-hydroxylase. This enzyme carries out the first of two reactions to convert vitamin D to its active form, 1,25-dihydroxy vitamin D3, also known as calcitriol.
Vitamin D can be acquired from foods in the diet or can be made in the body with the help of sunlight exposure. When active, this vitamin is involved in maintaining the proper balance of several minerals in the body, including calcium and phosphate, which are essential for the normal formation of bones and teeth. One of vitamin D's major roles is to control the absorption of calcium and phosphate from the intestines into the bloodstream. Vitamin D is also involved in several processes such as methylation, hormone synthesis, and immune health.
CYP2R1 is an enzyme responsible for the first step in converting vitamin D to its active form. It converts both vitamin D2 and D3 into the intermediary, inactive form of vitamin D (25-hydroxyvitamin D) in the liver. A genetic variation in this gene has been associated with selective 25-hydroxyvitamin D deficiency.
The G-allele has been shown to be almost 3.7 times more likely to be insufficient in vitamin D. Ensure adequate vitamin D intake, UV exposure and supplementation of vitamin D.
When looking at your overall need for vitamin D, it is important to consider your genotype for VDR, DBP, and GC too.