An evaluation of the relative contributions of exposure to sunlight and of diet to the circulating concentrations of 25-hydroxyvitamin D in an elderly nursing home population in Boston.
Webb AR, Pilbeam C, Hanafin N, Holick MF.
Am J Clin Nutr. 1990 Jun;51(6):1075-81.
PMID: 2349922
Low serum 25-hydroxyvitamin D concentrations and secondary hyperparathyroidism in middle-aged white strict vegetarians.
Lamberg-Allardt C, Kärkkäinen M, Seppänen R, Biström H.
Am J Clin Nutr. 1993 Nov;58(5):684-9.
PMID: 8237875
In conclusion, white strict vegetarians are at risk of vitamin D deficiency, at least in the winter, primarily because of a low dietary vitamin D intake, despite a normal sunlight exposure in summer. Low serum 25(OH)D concentrations are accompanied by high S-iPTH concentrations, which also are affected by a low calcium intake. The effect of these changes on bone health remains to be evaluated.