Subclinical health effects in a population exposed to excess vitamin D in milk.

To evaluate subclinical health effects of excess vitamin D, a cross-sectional study was conducted of persons consuming milk from a dairy that had overfortified milk for at least 4 years. Milk consumption, sunlight exposure, medical symptoms, serum 25-hydroxyvitamin D (25[OH]D), serum and urinary calcium, and indicators of renal function were measured. Increased milk consumption was associated with increased serum 25(OH)D and urinary calcium. However, the prevalences of elevated serum 25(OH)D and calcium were no greater than expected, and data indicated normal renal function. It was concluded that most persons exposed to excess vitamin D exhibited no measurable adverse subclinical effects.