The effect of vitamin D from cod-liver oil and a tuna-liver oil upon serum phosphatase concentrations in rachitic infants

Abstract

I N RECENT years the dual assay method, I using rats and chicks for distinguishing between the various forms of vitamin D found in liver oils of different spee, ies of fish, has become the usual procedure. Using this technique, Bills, Massengale, Imboden and IIalF reported assays on liver oils from twenty-five species of fish. They found that l'at unit for rat unit the oils differed widely in their relative effectivehess on chicks as measured by the ash content of the femurs. Correll and Wise, a, 4 found a variation in the response of chicks to certai.n tunaliver oils when fed at equal rat unit levels, as measured by bone ash, g'rowth, and serum phosphatase. Bills and co-workers 2 suggested tha t the different biologie responses obtained with chickens when compared with rats might be due to the existence of vi tamin D in several different chemical forms in a . s ingle oil, some chemieal entities for a par t icu lar specie being more efficient than others. I t has been repor ted by Barnes a n d ' C a r p e n t e r s tha t serum phosphatase values in otherwise normal infants serve as a sound basis for the clinical diagnosis and prognosis of rickets. We were interested, therefore, to aseertain how cod-liver oil and a tuna-l iver oil (known to be less efficient than cod-liver oil on chieks) would compare as to their effect on the magni tude and ra te of reduct ion of serum phosphatase when administered to rachit ic infants at equal ra t unit dosages (600, 900, and 2,400 I. U. dai ly) . The purpose of this paper is to repor t data on for ty-eight rachitic infants subjected to such a study.