The amount of gluten in our diet is greater than that of our ancestors. Part of the reason for this is the replacement of traditional wheat strains with new ones containing higher amounts of gluten.
These days we eat not only bread, but breakfast cereals made from wheat, and processed foods with gluten added to them. Even pharmaceuticals and shampoos contain gluten.
Some people who have both vitiligo and gluten intolerance, and have gone on gluten free diets have noticed that their white patches have reduced in size or even disappeared.
Here's a link to an interesting article about Vitiligo, celiac disease and gluten intolerance:vitiligo and gluten intolerance