Deficiency of vitamin D is usually caused by dietary deficiency and/or lack of exposure to sunlight in dark skinned individuals living at northern latitudes. Simple vitamin D deficiency is commonly treated by prescribing a vitamin D containing calcium supplement. This report presents a patient who rejected this approach and instead, after researching alternative treatment options independently, opted to self-treat by consuming UVB-irradiated mushrooms. The beneficial effect of this on the patient's plasma biochemical markers is shown. Further research into the beneficial effect of consuming UVB-irradiated mushrooms is required.