In the study, vitamin D levels (serum 25-hydroxyvitamin D) were measured in 5,518 residents of Tokyo. Those with levels of 30 ng/mL or higherOnly 2% of the total had normal values,
19% had vitamin D deficiency at 20–30 ng/mL, and a staggering 79% were classified as having vitamin D deficiency below 20 ng/mL.In other words, 98% of Tokyo residents were deficient in vitamin D.

