Sun beds had increased blood serum vitamin D levels by around 40% after six weeks. The ten 20-35 year old Nowegian volunteers were exposed to the bed twice a week for four weeks. The exposures started at one MED (minimal erythema dose) and rose to 2 MEDs across the period.

When the exposures stopped half of the volunteers were given a daily D3 supplement of 200 international units (iu) in cod liver oil, half no supplement. The supplement was too low a level to prolong significantly the benefit gained from the bed. Within eight weeks of stopping the sun bed exposures the D3 levels of both the 'supplement group' and the 'no supplement grop' had returned to their starting points.

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Exposure to ultraviolet B (UVB) radiation from a sun bed for ten minutes three times a week for six months tripled vitamin D levels after only four weeks.

After six months of treatment, her levels had been restored to within the normal, healthy range and she was free of the muscle weakness and bone and muscle pain that had made her life such a misery before.

The 57-year-old woman, who had had a long history of Crohn’s disease and short-bowel syndrome. Three bowel operations had left her with only two feet of small intestineand she had found it impossible to increase her blood vitamin D3 levels through dietary supplements.

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