3. Sources of vitamin D

More than 90% of vitamin D requirement comes from sunlight. According to Holick, exposure of ≥20% of the body's surface to either direct sunlight or tanning Vitamin D in Rheumatic Diseases: Interpretation and Significance DOI: http://dx.doi.org/10.5772/intechopen.88677

bed radiation is effective in increasing blood concentrations of vitamin D3 and 25-hydroxyvitamin D3 [25(OH)D3]. One minimal erythemal dose (MED) is equivalent to 10–50 times the recommended intakes [3]. Oily fishlike salmon, mackerel, sardines, and cod liver oil are also considered good sources of vitamin D [13].
