Asian osteomalacia is determined by dietary factors when exposure to ultraviolet radiation is restricted: a risk factor model.

Twenty-seven previously osteomalacic and 77 normal Asian women participated in a seven-day survey of dietary intake and daylight outdoor exposure. Individual levels of daylight outdoor exposure discriminated poorly between normal and osteomalacic women. The presence of osteomalacia was strongly related to varying degrees of vegetarianism. Lactovegetarianism (no meat, fish or egg consumption) was associated with significantly greater osteomalacic risk than ovolactovegetarianism (no meat or fish consumption). Unlike Asian rickets, high-extraction wheat cereal as chapatti was not a significant risk factor for osteomalacia in Asian women and dietary fibre was a less important risk factor than absent dietary meat, fish or egg. When exposure to ultraviolet radiation is limited, Asian osteomalacia (and Asian rickets) are determined by dietary factors.

The importance of limited exposure to ultraviolet radiation and dietary factors in the aetiology of Asian rickets: a risk-factor model.

Regional variation in the prevalence of Asian rickets was examined in Coventry, Bradford and Glasgow. Records of 152 weeks of daylight outdoor exposure were obtained from 104 Glasgow Asian children, 53 of whom had been treated for rickets. Records of seven-day weighed dietary intake were obtained from 84 Asian children, 43 of whom had been treated for rickets. There was a marked north-south gradient in the prevalence of Asian rickets. In all cases of severe rickets with deformity the child was vegetarian. Severe rickets was associated with lower intake of meat, higher intake of chapati and lower daylight outdoor exposure values than in normal children. Multivariate analysis employing a combination of these variables provided good separation between rachitic and normal groups. A risk-factor model is proposed which suggests that regional variation in the prevalence of rickets among Asian communities in Britain is mainly determined by the effects of latitude and the nature of the urban environment on available ultraviolet radiation. Where UV radiation is restricted, individual propensity to rickets within a given Asian community is mainly determined by dietary factors.

Relationships between radiological and biochemical evidence of rickets in Asian schoolchildren.

One hundred Asian schoolchildren provided evidence of the relationships between radiological and biochemical evidence of rickets in a vitamin D-deficient population. In a retrospective study of the X-rays of 56 children the variables serum alkaline phosphatase, inorganic phosphorus and age provided a discriminant function which correctly classified 10 of 11 children with radiological evidence of rickets and 44 of 45 children with negative or marginally abnormal X-rays. When the discriminant function was applied to a prospective study of 44 children, three children with radiological evidence of rickets were correctly classified together with 38 of the remaining 41 children with negative or marginally abnormal X-rays. Serum alkaline phosphatase was the most important variable in the discriminant analysis, followed by serum inorganic phosphorus and age. Low levels of serum 25-hydroxy vitamin D (25-OHD) are of little value in predicting the severity of radiological evidence of rachitic bone disease in a vitamin D-deficient population.