It's difficult to poison the liver to the point of disease because its job is to neutralize poisons in the body, say researchers from the University of Arkansas for Medical Sciences in a study published in the February 2002 issue of "Toxicological Sciences." Although the liver is a tough, resilient organ, its capacity to detoxify harmful substances in the body can be overwhelmed. For example, alcohol is very toxic; and in alcoholic cirrhosis, the liver's ability to safely dispose of toxins is finally overwhelmed. Vitamin D may play a role in helping the liver deal with toxic overloads.
Liver Toxicity
According to German researchers in the December 2008 issue of the "British Journal of Clinical Pharmacology," liver toxicity, or hepatotoxicity, is rare and unpredictable. It is primarily associated as a side effect of various prescription drugs, and the U.S. Food and Drug Administration halts numerous drug trials because participants develop or show signs of liver toxicity. Further, there are some isolated cases of liver toxicity resulting from various herbs, supplements and over-the-counter drugs. However, with reference to vitamin D, there is evidence that the biologically active form may be protective against toxic damage.
Vitamin D Types
An overview of vitamin D in the December 2004 issue of the "American Journal of Clinical Nutrition" explains that vitamin D supplements are poor substitutes for the version manufactured by your body. Vitamin D's synthesis is complicated and starts in the skin under the presence of ultraviolet light and cholesterol. This preliminary form, which is named 7-dehydrocholesterol, is transported to the liver where it's metabolized into 25-hydroxyvitamin D3, or 25(OH)D3, and finally passed off to the kidney where it's converted into 1α,25-dihydroxyvitamin D3, or 1,25(OH)2D3. While the middle version is the circulating form, the final product -- 1,25(OH)2D3 -- is the hormonal and biologically active version.
Hormonal D3 Protection
Chinese researchers reporting in the July 2010 issue of "Acta Pharmacologica Sinica" experimented on mice to investigate if administering 1,25(OH)2D3, the hormonal version of vitamin D, could prevent the onset of liver disease. The researchers prepared a solution of vitamin D and injected it into the abdomens of mice. One hour later they induced liver disease by injecting a toxin into their tail veins. Then, for the next seven days, they injected booster doses of vitamin D once a day. The researchers were surprised by how potent the protection was -- none of the experimental mice developed liver disease.
Deficiency
A study from the University of Tennessee Health Science Center, published in the September 2010 issue of "Digestive Disease and Sciences," investigated the prevalence of vitamin D deficiency among patients with chronic liver disease. The diseases surveyed included hepatitis C with complications from cirrhosis and hepatitis C without cirrhotic complications. Cirrhosis simply refers to the presence of physical damage to the liver. The researchers found that vitamin D deficiency was remarkably common among patients -- more than 92 percent suffered vitamin D deficiency. Severe deficiency was seen more often in patients with cirrhosis compared with noncirrhotics.
References
- "Toxicological Sciences"; Mechanisms of Hepatotoxicity; Hartmut Jaeschke, et al.; February 2002
- "British Journal of Clinical Pharmacology"; Causality Assessment in Hepatotoxicity by Drugs and Dietary Supplements; Rolf Teschke, et al.; December 2008
- "American Journal of Clinical Nutrition"; Overview of General Physiologic Features and Functions of Vitamin D; Hector DeLuca; December 2004
- "Acta Pharmacologica Sinica"; Preventive Effects of 1,25-(OH)2VD3 Against ConA-induced Mouse Hepatitis Through Promoting Vitamin D Receptor Gene Expression; Xu-dong Hu, et al.; July 2010
- "Digestive Diseases and Sciences"; Prevalence of Vitamin D Deficiency in Chronic Liver Disease"; J. Arteh, et al.; September 2010
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