Diabetes injures the liver, causing oxidative stress, fatty infiltrations and liver dysfunction. One way to study the effect of large doses of vitamin D on diabetes and liver dysfunction is to give rats vitamin D and study mitochondrial (“power plants” of the cell) dysfunction.
In a study from this year, Dr Naijl George and colleagues in India induced a highly damaging oxidative state in rats by giving them streptozotocin, a toxin that damages the liver and pancreas, causing diabetes and liver injuries.
George N, Peeyush Kumar T, Antony S, Jayanarayanan S, Paulose CS. Effect of vitamin D3 in reducing metabolic and oxidative stress in the liver of streptozotocin-induced diabetic rats. Br J Nutr. 2012 Jan 6:1-9.
For our purposes, they had two groups of rats, half treated with 300 IU of vitamin D /kg of body weight/day and half only had the vitamin D contained in regular rat chow, which is not much.
The authors made before and after measurements of biochemical indices of oxidative stress, such as the master antioxidants, glutathione and superoxide dismutase. They also looked at a measure of mitochondrial damage, an enzyme called malate dehydrogenase.
All the rats rapidly developed oxidative stress and diabetes after the administration of streptozotocin. However, measurements of oxidative stress and mitochondrial damage quickly reverted to normal in the vitamin D treated rats but not in the placebo treated rats. While all rats developed diabetes, the vitamin D rats had much better blood sugars and other measurements of diabetic severity, as well as much less evidence of liver injury.
The authors concluded,
“The results provide evidence for antidiabetic and hepato-protective properties of vitamin D3. Considering that the treatment of diabetes is hampered by the well-known ability of insulin to induce profound and life-threatening low blood sugar, (high dose) vitamin D3 represents a therapeutic possibility for the better management of diabetes-mediated hepatic complications and other liver diseases.”