a1 University Department of Human Nutrition, Royal Infirmary, Glasgow, UK
a2 Department of Psychiatry, Hairmyres Hospital, East Kilbride, UK
a3 Public Health & Health Policy, Division of Community Based Sciences, University of Glasgow, UK
a4 University Department of Medicine, Royal Infirmary, Manchester, UK
Endogenous vitamin D deficiency (low serum 25(OH)D3) is a necessary but insufficient requirement for the genesis of vitamin D-deficiency rickets and osteomalacia. The magnitude of the independent contributions of dietary factors to rachitic and osteomalacic risk remains uncertain. We reanalysed two weighed dietary surveys of sixty-two cases of rickets and osteomalacia and 113 normal women and children. The independent associations of four dietary variables (vitamin D, Ca, fibre and meat intakes) and daylight outdoor exposure with rachitic and osteomalacic relative risk were estimated by multivariate logistic regression. Meat and fibre intakes showed significant negative and positive associations respectively with rachitic and osteomalacic relative risk (RR; zero meat intake: RR 29·8 (95 % CI 4·96, 181), P<0·001; fibre intake: RR 1·53 (95 % CI 1·01, 2·32), P+0·043). The negative association of meat intakes with rachitic and osteomalacic relative risk was curvilinear; relative risk did not fall further at meat intakes above 60 g daily. Daylight outdoor exposure showed a significant negative association with combined relative risk (RR 0·33 (95 % CI 0·17, 0·66), P<0·001). Operation of the meat and fibre risk factors was related to sex, age and dietary pattern (omnivore/lactovegetarian), mainly determined by religious affiliation. The mechanism by which meat reduces rachitic and osteomalacic risk is uncertain and appears independent of revised estimates of meat vitamin D content. The meat content of the omnivore Western diet may explain its high degree of protection against nutritional rickets and osteomalacia from infancy to old age in the presence of endogenous vitamin D deficiency.
(Received January 23 2005)
(Revised May 06 2005)
(Accepted June 20 2005)