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Letter to the Editor

Vitamin D Mysteries: A Response to Stumpf and Bidmon

Department of Nutritional Sciences, University of California, Berkeley, CA 94720-3104

Dear Dr. Suttie,

We have appreciated the opportunity of seeing Stumpf and Bidmon’s letter.

We are sorry not to have known of their papers when preparing ours (Carpenter and Zhao 1999 ). Their work gives reason to expect that molecules with vitamin D activity will be present on the skin and fur of rats that have an adequate supply of the vitamin (Stumpf 1995 ).

Where, in Steenbock’s work, an irradiated rat conferred protection from rickets on a nonirradiated cage mate (Steenbock and Black 1924 ), the presence of active molecules on the coat of the former could certainly have been the source of the latter’s protection. Also when one cage of irradiated rats was placed on top of a control cage (Nelson and Steenbock 1925a ), it could again have been particles of skin and fur falling down and being eaten by the animals below that protected them, although the potency of these fragments would have had to be surprisingly high.

However, in further experiments by Steenbock’s group, the wire screens on the floors of cages previously occupied by nonirradiated rats were a source of vitamin D activity when they were irradiated in the absence of rats (Nelson and Steenbock 1925b ). It appeared, therefore, that whatever had come onto the screens from the rats was only a precursor that needed to be irradiated before it displayed vitamin D activity. The two possible sources of such precursor(s) appear to be grease from the fur, or from fecal pellets.

We join Drs. Stumpf and Bidmon in hoping that workers with the necessary facilities and experience will soon put the hypotheses to a direct test, and explain what has remained a mystery for so long.

REFERENCES

1. Carpenter K. J., Zhao L. Forgotten mysteries in the early history of vitamin D. J. Nutr. 1999;129:923-927[Abstract/Free Full Text]

2. Nelson E. M., Steenbock H. Further observations on the anti-rachitic action of the irradiated animals on the nonirradiated when placed in the same cage. Am. J. Physiol. 1925a;73:341-345[Free Full Text]

3. Nelson E. M., Steenbock H. Observations bearing on the alleged induction of growth-promoting properties in air by irradiation with ultraviolet light. J. Biol. Chem. 1925b;62:575-593[Free Full Text]

4. Steenbock H., Black A. The induction of growth-promoting and calcifying properties in a ration by exposure to ultraviolet light. J. Biol. Chem. 1924;61:405-422[Free Full Text]

5. Stumpf W. E. Vitamin D sites and mechanisms of action: a histochemical perspective. Reflections on the utility of autoradiography and cytopharmacology for drug targeting. Histochem. Cell Biol. 1995;104:417-427[Medline]

6. Stumpf W. E., Bidmon H.-J. "Vitamin D mysteries"? Secretions and sloughings from skin and oral-gastrointestinal mucosa contain hormone. J. Nutr. 2000;130:264[Free Full Text]

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