In summer, fewer Austrians tend to think about vitamin D deficiency. In contrast to the darker months of the year, there is a larger time window for a short walk in daylight to soak up the necessary dose of sun. To put it simply, vitamin D3 is formed when UV light converts a precursor, provitamin D3. Depending on skin type and time of year, five to twenty minutes in the sun should be enough with your face and arms uncovered.
Genetically Modified Tomatoes May Counteract Vitamin D Deficiency – Nature
