Lack of vitamin A - found in many fruits, vegetables, meats and dairy products - may be involved in development of type 2 diabetes, according to researchers.
The condition is characterized by insulin resistance, in which insulin-producing beta cells in the pancreas are unable to function effectively.
According to senior author Dr. Lorraine Gudas - chairman of the Department of Pharmacology at Weill Cornell - and colleagues, vitamin A boosts beta cell activity, meaning lack of the vitamin may play a role in the development of type 2 diabetes.
There are two types of vitamin A. Preformed vitamin A, referred to as retinol, is present in meat, poultry, fish and dairy products, while pro-vitamin A, or beta-carotene, is found in many fruits and vegetables. Vitamin A aids cell growth and contributes to a healthy immune system and vision.
Past studies have shown that, during fetal development, vitamin A is key for beta cell production. But Dr. Gudas and colleagues say it was unclear as to whether vitamin A played such a role in adulthood.
Removal of dietary vitamin A led to beta cell loss in adult mice
To find out, the team analyzed the beta cell development among two groups of adult mice; one group of mice had been genetically modified to be unable to store dietary vitamin A, while the other group was able to store the vitamin from foods as normal.
The researchers found that the mice unable to store vitamin A experienced beta cell death, meaning these mice were unable to produce insulin.
What is more, when the researchers removed vitamin A from the diets of healthy mice, they found this led to significant beta cell loss, resulting in reduced insulin production and increased blood glucose levels - key factors involved in development of type 2 diabetes. When the researchers restored vitamin A to the rodents' diets, beta cell production rose, insulin production increased and blood glucose levels returned to normal.
The researchers say their findings indicate that vitamin A deficiency may be involved in the development of type 2 diabetes. Dr. Gudas says:
"How the removal of vitamin A causes the death of the beta cells that make insulin in the pancreas is an important question we want to answer.
These beta cells in the pancreas are exquisitely sensitive to the dietary removal of vitamin A. No one has found that before. Our study sets the platform to take these studies further into preclinical and clinical settings."
The team says their findings also suggest a synthetic form of vitamin A may have the potential to reverse type 2 diabetes - something they plan to address in future research.
In November 2014, Medical News Today reported on a study suggesting verapamil - a common drug used to treat high blood pressure, irregular heartbeat and migraine headaches - has the potential to reverse diabetes.