During their various studies of the clinical use of massive doses of vitamin D, Reed and associates1 noted that many patients receiving large doses of vitamin A and vitamin D claimed that both the incidence and the severity of their colds were appreciably reduced. No accurate statistics were kept, but it appeared to them that only those subjects receiving both vitamins were thus benefited.
This observation was not surprising since many investigators have noted great reduction in the incidence of colds and respiratory infections through the use of fairly liberal quantities of cod liver oil. Holmes and his colleagues,2 for example, reviewed the subject and showed a reduction of about two thirds in the average "lost time" of industrial workers due to colds and respiratory diseases when cod liver oil was furnished. In general Holmes felt that the reduction in colds was due to the vitamin A content of the
SPIESMAN IG. MASSIVE DOSES OF VITAMINS A AND D IN THE PREVENTION OF THE COMMON COLD. Arch Otolaryngol. 1941;34(4):787-791. doi:10.1001/archotol.1941.00660040843010