Vitamin D is a unique vitamin because it is produced by your skin and also found in the foods you eat. Vitamin D is a fat-soluble vitamin, meaning your body can break it down and also store it, as compared to water-soluble vitamins, which you must replenish every day. The main body organ that breaks down vitamin D is the liver. Under normal circumstances, the liver can break down vitamin D without issue. However, when liver function is impaired, vitamin D deficiency can occur.
Conversion
When your skin is exposed to the sun, your cells make vitamin D, some of which travels to the liver. The same is true for when you consume vitamin D from food sources like egg yolks, fortified milk, pink salmon or fortified cereal: vitamin D is transported to your liver. Your liver houses extra oxygen and hydrogen molecules that combine with vitamin D to form 25-hydroxyvitamin D, which is also referred to 25(OH)D. After this action, the liver transports the vitamin D to the kidneys, where it is further broken down for use.
Serum Calcium Levels
When the liver releases 25(OH)D, this triggers another chemical reaction in the body: the release of parathyroid hormone from the brain. Parathyroid hormones stimulate the body to absorb calcium, which helps your body build strong bones. If your liver does not properly absorb vitamin D, your body may not be able to build strong bones. Low levels of vitamin D in the body mean your body only absorbs 10 to 15 percent of the calcium you consume.
Vitamin D and Liver Disease
When the liver is affected due to conditions like chronic liver disease, you are more likely to experience vitamin D deficiencies. This is problematic because if your liver cannot process vitamin D, your bones may become more brittle, which increases your risk for osteoporosis and bone breakage. If you have been diagnosed with impaired liver function, your physician may recommend a blood test to check your vitamin D levels.
Considerations
The recommended vitamin D daily intake for those ages 1 to 70 is 600 IU per day. However, if your liver function is impaired, your body cannot convert vitamin D into usable forms. Your physician may recommend osteoporosis medications to help your body more effectively use vitamin D and calcium.
References
- Linus Pauling Institute at Oregon State University; Vitamin D; Jane Higdon, Ph.D.; March 2004
- Colorado State University; Vitamin D (Calcitrol); R. Bowen; April 24, 2010
- Science Daily; Vitamin D Deficiency Common in Patients with IBD, Chronic Liver Disease; October 2008
- Harvard Health Publications; Vitamin D and Your Health; Feb. 2007
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