Rural rickets: vitamin D deficiency in a post-medieval farming community from the Netherlands

Abstract

Ricketsis caused by vitamin D deficiency as a result of limited exposure tosunlight and inadequate diet. In the 19th century, rickets wasendemic inmost northern European cities. In post-MedievalNetherlands, rickets is documented in low frequencies in a few urbansamples, but has not been studied in contemporaneous ruralpopulations. Beemster is a rural farming community in the Netherlandsthat was established in the 17th century upon drained land, withtheMiddenbeemster cemetery in use until 1866 AD. Ninety-fiveindividuals fromthe ages of 32 weeks in utero to 15 years wereexamined for rickets in order to understand factors that can causevitamin D deficiencyin rural, non-industrialized populations. To identify rickets in theBeemster sample, ten features were scored, with bending deformitiesof the lower limb and one other feature, or at least threenon-bending features, having to be present in order for diagnosis.Nine individuals (9.5%) had evidence of rickets—a high prevalence,especially for a rural community where ample sunlight was available.The two and three year old Beemster infants were most heavilyaffected with an age-specific prevalence of 30.4%. Twothree-month-old infants also had rickets. Some of the affected mayhave developed rickets secondarily, as a result of a differentillness, but cultural practices including prolonged swaddling,occlusive clothing, and keeping the young indoors, are suggested tohave contributed to this high rickets prevalence. Dietary variablesincluding poor weaning foods and common episodes of malnutrition mayhave also contributed to vitamin D deficiency. This studydemonstrates the value of careful analysis of pathological conditionsin subadults and highlights that rickets was not only a disease ofcities, but affected populations that would appear to have been atlow risk, because of maladaptive cultural practices.