A simple change in diet could boost vitamin D levels in Type 2 diabetics, according to new research from Iowa State University.

The findings, published in the Journal of Agricultural and Food Chemistry, are significant because diabetics have trouble retaining vitamin D, which is important for bone health and protecting against cancer and other diseases.

The Iowa State researchers found diabetic rats fed an egg-based diet had higher concentrations of the form of vitamin D known as 25-hydroxyvitamin D-3, as well as improved blood glucose levels. They also gained less weight over the course of the study than those who did not eat the egg-based diet.

"Eggs are the richest source of 25-hydroxyvitamin D-3 in the diet, and there isn't any conversion required to make it into the blood. If you take it in a supplement or food fortified with vitamin D, it has to be converted to that form," said Matthew Rowling, an associate professor of food science and human nutrition.

Blood glucose levels dropped nearly 50 percent for diabetic rats on an egg-based diet, compared to those fed a standard diet. Concentrations of the vitamin were 148 percent higher for the egg-fed group and plasma triglyceride concentrations — a risk factor for cardiovascular disease — dropped 52 percent.