This past weekend I covered the annual meeting of the Pediatric Endocrine Society in Washington, and in preparation I was looking through the abstracts available online. This one caught my eye:
"Dr. Mellanby's Puppies: The Discovery of Dietary Vitamin D in Edwardian England," by V. Houston and C. Michie of Ealing Hospital in London.
The authors wrote, "By the later 1800s the majority of English and American children living in poverty suffered rickets. Proposed causes included confinement, infection, and sunlight deficiency." The disease likely was an important contributor to child mortality at the time, with affected children developing characteristic skeletal deformities, bone pain and softening, and weakness.
Apparently, in 1914 the medical research committee at King's College for Women in London asked young researcher Edward Mellanby to investigate the cause of rickets. Suspecting a nutritional cause, Mellanby spent the next 5 years performing dietary elimination experiments on some 400 puppies. He first found that by feeding the dogs a diet consisting exclusively of oat porridge, they developed rickets. The animals also had been deprived of sunlight, having been kept indoors throughout the experiments.
In Houston and Michie's abstract, they noted that when Mellanby added certain oils and animal fats such as butter the puppies didn't develop the bone abnormalities. In fact, those animals given linseed or cod liver oil were found to have 21% to 28% more calcium in their bones.
By 1919, Mellanby had concluded that rickets was a disease of malnutrition that was curable with regular doses of cod liver oil. Writing in the Lancet, he stated, "Rickets is a deficiency disease which develops in consequence of the absence of some accessory food factor or factors. It therefore seems probable that the cause of rickets is a diminished intake of an anti-rachitic factor."
A decade later German chemist Adolf Windaus was awarded the Nobel prize in chemistry for his work on vitamins, particularly vitamin D and sunlight.
Mellanby's experiments and those who followed him during the 1920s apparently had a dramatic impact on the prevention and treatment of rickets in England, because when a trial for a commercial preparation of vitamin D was planned in the 1930s, there were no children with rickets to be found in London.
I was happy to find the poster at the meeting this weekend and see it for myself.