On the adulteration of bread as a cause of rickets. 1857

New thoughts concerning the epidemic of rickets: was the role of alum overlooked?

Recent emphasis on the re-emergence of nutritional rickets has renewed interest in the etiology and therapy of this devastating disorder. At its peak in the 19th and 20th century, rickets was a major area of study for countless experts in childhood disorders and numerous theories abounded as to its cause. These included, among others, infections, confinement or intestinal disturbances, and were largely discarded after the discovery of the role of vitamin D and the importance of ultraviolet irradiation. Once a good explanation had been found for the cause of the disorder and the curative power of vitamin D proven, whether it was obtained from the diet or through exposure to sunlight, there was no apparent need to look any further into the etiology of rickets. But in fact there may have been other contributory factors, recognition of which might have lessened the severity of the disease or hastened recovery. One of these theories might be of particular interest to pediatric nephrologists because it relates to insoluble aluminum-based phosphate binders. Namely, alum used as an adulterant in bread in certain locations may have contributed to metabolic bone disease during the great epidemic of rickets.

Nutritional rickets: deficiency of vitamin D, calcium, or both?

Nutritional rickets remains a public health problem in many countries, despite dramatic declines in the prevalence of the condition in many developed countries since the discoveries of vitamin D and the role of ultraviolet light in prevention. The disease continues to be problematic among infants in many communities, especially among infants who are exclusively breast-fed, infants and children of dark-skinned immigrants living in temperate climates, infants and their mothers in the Middle East, and infants and children in many developing countries in the tropics and subtropics, such as Nigeria, Ethiopia, Yemen, and Bangladesh. Vitamin D deficiency remains the major cause of rickets among young infants in most countries, because breast milk is low in vitamin D and its metabolites and social and religious customs and/or climatic conditions often prevent adequate ultraviolet light exposure. In sunny countries such as Nigeria, South Africa, and Bangladesh, such factors do not apply. Studies indicated that the disease occurs among older toddlers and children and probably is attributable to low dietary calcium intakes, which are characteristic of cereal-based diets with limited variety and little access to dairy products. In such situations, calcium supplements alone result in healing of the bone disease. Studies among Asian children and African American toddlers suggested that low dietary calcium intakes result in increased catabolism of vitamin D and the development of vitamin D deficiency and rickets. Dietary calcium deficiency and vitamin D deficiency represent 2 ends of the spectrum for the pathogenesis of nutritional rickets, with a combination of the 2 in the middle.

John Snow and research

John Snow's leadership in epidemiology as well as anaesthesia resulted from his research as much as his clinical practice. In anaesthesia, Snow's research concerned the regulation of concentrations of volatile agents and the development of efficient inhalers; the uptake and elimination of volatile agents; stages of anaesthesia; carbon dioxide metabolism and rebreathing; and metabolism in anaesthesia and the theory of anaesthesia. In epidemiology, Snow investigated the relationship of water supplies to mortality in cholera during the London epidemic in 1854, which led him to formulate an original and valid theory of the transmission of cholera. Snow's research, which has received less attention than anecdotes concerning his career (e.g., his anaesthetizing Queen Victoria and urging removal of the handle of a contaminated water pump), was always directed towards solving specific problems. The significance of his research is evident in its leading not only to improvements in health care but also to the evolution of anaesthesia and epidemiology as professional disciplines.