Commercially available sun lamps and vitamin D formation.

Four commercially available, medium pressure mercury sun lamps were used to assess their effects on promoting vitamin D synthesis in the skin. It was found that all the lamps studied had vitamin D synthesizing spectral wavelengths and caused an increase in the serum concentrations of 25-hydroxyvitamin D. However, the ultraviolet and visible irradiance measurements showed that a considerable proportion of the ultraviolet radiation was below 290 nm. It was not surprising, therefore, to find that these lamps caused adverse skin reactions. While a useful rise in vitamin D production can be obtained with these sun lamps, the difficulty involved in avoiding skin reaction limits their usefulness. Such lamps are unlikely to provide a safe practical routine method for the prevention of vitamin D deficiency in the home.