Vitiligo is a pigmentation disorder of the skin in which the melanocytes (the cells that make pigment) are destroyed resulting in whitish patches appearing on the skin. It has no known specific cause.

It is possible that it can be caused by fungal infection, some hair dyes (containing phenylenediamines), prolonged stress, psychological distress, sub-clinical thyroid imbalance or auto-immune problems that may prevent the skin producing melanin (the
coloured pigment of the skin) from L-tyrosine via the enzyme tyrosinase.

Vitiligo may also be made worse by the use of beta-blocking drugs. Also, through a series of chemical reactions in the body it is possible that there may be excessive amounts of hydrogen peroxide in the involved areas of epidermis as well as an increase in free radicals.

Check first that hair dyes and/or beta-blockers are not involved.

Also, (especially if a recent trip has been made overseas to island areas), treat the affected areas with an anti-fungal preparation.

The next step would be to greatly increase mineral levels in the body as this will help the skin heal and also improve immune status.  I have seen success treating this problem simply by supplementing with minerals. The mineral supplement used was Barley Grass, in doses of about 3000mg daily, which would have had the combined effect of providing both more minerals to the body along with extra B Vitamins and proteins.

The addition of extra anti-oxidants would also be beneficial.

I have also found reference to the herb Polypodium Leucotomos helping in some cases of Vitiligo. It is a fern found in central America which has a long traditional use as a blood tonic. Its mode of action being to stimulate the immune system by increasing the lymphocyte level.
It is possible that if this the case, then other herbs such as Echinacea, Astragalus and Phyllanthus and other immune boosting herbs could also possibly work as the effects in the body are similar.

In a recent publication I also found the following reference to some research done in India to the effect that Ginkgo Biloba is capable of helping to arrest the spread of depigmentation. In some of the research group the skin was actually repigmented.
The dose used was high, 40mg three times daily and was tried because of the combined anti-oxidant and immuno-modulatory properties. This study was carried out over 6 months but it is possible that faster results could be obtained if combined with other similar therapies.

Other references were to Homeopathic treatments that appeared to be centred on improving the overall constitution of the body and reported slow but good results. This would also be worth looking into and could well get better results if combined with the use of minerals.

If thyroid problems are suspected (tendency to lethargy, gradual increase in weight, susceptible to cold etc), then the use of a supplement containing Potassium Iodide would be a great help.

Auto-immune problems can be helped by the use of increased minerals, herbal anti-inflammatories and digestive enzymes.

If psychological distress is a possibility, then counselling may be worth considering. It has been known to help in some instances.