Vitamin D & Liver Function
Vitamin D is not considered an essential vitamin for liver function, but liver function is essential to providing vitamin D to the body. The liver and kidneys change vitamin D to an active form, which actually is hormonal in nature. Because of this, people with liver disorders can develop vitamin D deficiencies.
Foods with vitamin D are few, mainly fatty fish liver, beef liver and eggs. It can be difficult to obtain enough this way, so some foods are fortified, including milk, cereal and bread. Vitamin D is also readily obtained from sun exposure, but still must be converted by the liver and kidneys for use.
Vitamin D Conversion
Conversion of vitamin D to its active form is called hydroxylation. The first hydroxylation occurs in the liver and the second in the kidneys.
People who have fat malabsorption, or difficulty absorbing dietary fat, may need vitamin D supplementation because it is fat soluble. Liver impairment can cause fat malabsorption.
Chronic Liver Disease
University of Tennessee researchers measured vitamin D levels of patients with chronic liver disease, such as hepatitis and cirrhosis, and found over 92 percent had some level of vitamin D deficiency.
Severe vitamin D deficiency in the Tennessee study was more likely in people with cirrhosis than with other liver issues.